National Academy of Sciences National Research Council NUCLEAR SCIENCE SERIES The Radiochemistry of Thorium b, NN AT 7 Energy = et LR . COMMITTEE ON CHEMICAL SCIENCES James. L. Kinsey, Cochairman, Massachusetts Institute of Technology Alan Schriesheim, Cochairman, Exxon Research and Engineering Company Andreas Acrivos, Stanford University AIIen\J_. Bard. University of Texas, Austin Fred Basolo, Northwesfern University Steven J. Benkovic, Pennsylvania State Universitf Bruce J. Berne, Columbia University R. Stephen Berry, University of Chicago Alfred E. Brown, Celanese Corporation Ernest L. Eliel, University of North Carolina Roald Hoffmann, Cornetl University Rudolph Pariser, E. . Du Pont de Nemours & Co., Inc. Norman Sutin, Brookhaven National Laboratory Barry M. Trost, University of Wisconsin Edel Wasserman, E. |. du Pont de Nemours & Co., inc. SUBCOMMITTEE ON NUCLEAR AND RADIOCHEMISTRY Gregory R. Chaoppin, Chairman, Florida State University Eugene T. Chulick, Babcock & Wilcox Co. Christopher Gatrousis, Lawrence Livermore National Laboratory Peter E. Haustein, Brookhaven National Laboratory Darleane C. Hoffman, Los Alamos National Laboratory Paul J. Karol, Carnegie-Mellon University Michael J. Welch, Washington University School of Medicine Raymond G. Wymer, Oak Ridge National Laboratory William H. Zoller, University of Maryland LIAISON MEMBERS Fred Basolo, Northwestern University Theodore L. Cairns, Greenville, Delaware Gerhart Friedlander, Brookhaven National Laboratory {(Membership as of January 1982} The Radiochemistry of Thorium By E. K. HYDE Lawrence Radiation Laboraiory Universily of California Berkeley, California January 1960 Reprinted by the Technical Information Center U. S. Department of Energy Subcommittee on Radiochemistry National Academy of Sciences —National Research Council Price $9.75. Available from: National Technical Information Service U. S. Department of Commerce Springfield, Virginia 22161 Printaed in the United Gtates of America USDOE Technical informaton Center, Oak Ridge. Tennessse 1960; latest printing June 1982 FOREWORD The Subcommlttee on Rediochemistry 1s one of a number of subcommittees working under the Committee on Nuclear Sclence within the National Academy of Sciences - National Research Counclil. Its members represent govermment, Industrial, and university laboratorles 1n the areass of nuclear chemlstry and analytical chemistry. The Subcommlttee has concerned 1tself with those areas of nuclear scilence which involve the chemlst, such as the collec- tilon and distribution of radliochemical procedures, the estab- lismment of specifications for radiochemically pure reagents, the problems of stockpiling unconteminated materials, the avaellability of cyclotron time for service irradlations, the place of radiochemistry in the undergraduate college program, etec. This series of momograephse has grown out of the need for up-to-date compllations of radiochemicel Information and pro- cedures. The Subcommlttee has endeavored to present a series which will be of maximm use to the working sclentist and which contains the lateat available Information. Each mono- graph collects in one volume the pertinent information required for rediochemical work with an Indlvidual element or & group of ¢closely related elements. An expert in the radiochemistry of the particular element has written the monograph, following a standard format developed by the Subcommittee. The Atomic Energy Commlssion has sponsored the printing of the serles. The Subcommittee 1s confident these publications will be useful not only to the radiochemist but also to the research worker 1n other fields such as physics, blochemistry or medlcine who wishes to use radiochemical techniquee to solve a specific problem. W. Wayne Meinke, Chslrman Subcommittee on Radiochemistry ill CONTENTS I. General Reviews of the Inorganic and Analytical Chemistry of Thorium ' II. General Reviews of the Radiochemistry of' Thorium ITI.Table of Isotopes of Thorium IV. Review of those Features of Thorium. Chemis'try of Chief Interest to 1. Radiochemlests Metalllic thorium Boluble salts of thorium Insoluble salts of thorlum and coprecipltation characteristics of thorium Complex ions of thorium Chelate complexes of thorium Extraction of the TTA-complex of thorium fnto organic solvents Extraction of thorium into organic solvents Ion Exchange behavior of thorium V. Collection of Detalled Radiochemical Procedures for Thorium. w W BREE o - INTRODUCTION This volume which deals with the radiochemistry of thorium is one of a series of monographs on radiochemistry of the elements. There is included a review of the nuclear and chemical features of particular interest to the radiochemist, a discussion of prob- lemg of dissolution of a sample and counting techniques, and finally, a collection of radiochemical procedures for the element as found in the literature. The series of monographs will cover all elements for which radiochemical procedures are pertinent. Plans include revision of the monograph periodically as new techniques and procedures warrant. The reader is therefore encouraged to call to the attention of the author any published or unpublished material on the radiochemistry of thorium which might be included in a revised version of the monograph. vi The Radiochemistry of Thorium E. K, HYDE Lawrence Radlation Laboratory University of Californie, Berkeley, California January 1960 Table of Isotopes I. GENERAL REVIEWS OF THE INORGANIC AND ANALYTICAL CEEMISTRY OF THORTUM Chapter 3, pp 16-66 in "The Chemistry of the Actinide Elements", J. J. Katz and G. T. Seaborg, John Wiley and Sons, Inc., New York, 1957. Chapter 4, pp 66-102, "The Chemistry of Thorium" by L. I. Katzin in the "The Attinide Elements", National Nuclear Energy Series, Division IV, Plutonium Project Record Volume 14A, edited by G. T. Seaborg and J. J. Ketz, McGrew-Hill Book Co., New York, 195&4. Gmelin's Handbuch der Anorganischen Chemie, System Nr. 44, 8th Edition (Verlag Chemie, GmbH. Weinheim-Bergstrasse, 1955). C. J. Rodden &nd J. C. Warf, pp 160-207 in "Analytical Chemlstry of the Manhattan Project", McGraw HEill Book Co., New York, 1950. "Thorium, pp 946-954, Vol. 1 of "Scott's Standard Methods of Chemical Analysis", K. H. Furman, editor, D. Van Noetrand Co., Inc., New York, 1939. "The Analytical Aspects of Thorium Chemistry", T. Mueller, G.K. Schweltzer and D. D. Starr, Chem. Rev. 42, Feb. 1948. Collected Papers on Methods of Analysis for Uranium and Thorlum compiled by F. 8. CGrimaldl, I. May, M. H. Fletcher and J. Titcomb. Geological Survey Bulletin 1006, 1954, for sale by Superintendent of Documents U. 8. Govermment Printing Office Washington 25, D. C. Price ¢ 1. - II. GENERAL REVIEWSOF THE RADIOCHEMISTRY OF THORIUM Chapter 15, "Radiochemical Separations of the Actinide Elements", by E. K. Hyde in "The Actinide Elements", edited by G. T. Seaborg end J. J. Katz, McGraw Hill Book Co., New York, 195L. Paper P/728, "Radliochemical Separations Methods for the Actinide Elements" by E. K. Hyde, pp. 281-303, Vol 7, Proceedings of the International Conference in Geneve, August 1955 on the Peaceful Uses of Atamic Energy, United Nations, New York, 1956. Single copies of this paper may be available for 25 cents from United Natlons Book- stare, New York City. IIT. TAHLE OF ISOTOPES OF THORIUM Isotope Half 1life Type of Method of Preparation Decay rn2e3 ~0.1 sec o Demghter 1.3 min UPZ! Thzah ~1l Bec a Daughter 9.3 min 0228 ' The22 8 mn a ~90% Daughter 58 min y229 EC ~10% Tn?26 30.9 min a Daughter 20.8 day UZ0° ThE2l 18.17 dsy a Netural redicactivity; dsughter AcZZ! (RdAc) - T'J:L228 1.91 year a Netural radiocactivity; dsughter MZZB (RATh) (MsTh,, ) 229 7340 year o Daughter U233 Th23° 80,000 year a Natural radicactivity; daughter Uz3h (Ionium) %’hZ?l 25.64 hour B Natural radiosctivity; dsughter U237 UY ™?32 1,39 x 10¥%ear < Natural thorium 1s 100% Th232 233 22.1 min B- ThZ32 4+ neutrons :(uh23;' 24.1 day B- Natural radlosctivity; dmughter U230 Uxy For more complete information on the radiations of the thorium isotopes and for references to original literature, see "Table of Isotopes”, D. Strom- inger, J. M. Hollander and G. T. Besborg, Reviews of Modern Physics, 30, No.2, Part II, April 1958. | IV. REVIEW OF THOSE FEATURES OF THORTUM CHEMISTRY OF CHIEF IRTEREST TO RADIOCHEMIOSTS 1l. Metgllic Thorium Thorium metal is highly electropositive and its preparation is a matter of no mean difficulty. Methods which are used for this purpose include re- ductlon of thorlum oxide with calclum, reduction of thorium tetrachloride or tetrafluoride or tetrachloride by calcium, megnesium or sodium or electrolysis of fused salts. Thorium metal has a high melting point (1750° C) and is highly reactive in the molten state. The potential of the thorium-thorium (IV) couple has been egtimated as + 1.90 volts.l A fresh surface of thorium tar- nishes rapidly in alr and the finely divided metal 18 pyrophoric. The pres- ence of oxygen and poselbly of nitrogen and other light element impurities on the surface of thorium can be a matter of some importance in some experi- ments in nuclear chemlstry or physics where thin foils of thorium are employed a8 targets. The reaction of thorlum metal with agueous mineral acids has some featbures of grea-t Interest to radiochemists. Dilute.hydrofluoric aclid, nitric mecid, sulfuric acid end concentrated phosphoric acld or perchloric ecld attack mas- slve thorium metal slowly. Concentrated nitric acid rendere thorium passive but the additlon of fluoride ion ceuses the dissolutlon to contimue. In the dissolution of small thorium targets, 1t is found that concentrated HRO3 con- talning 0.0l molar (N]Ih)z SiF, (or HF) mekes a good solvent mixture. The sol- vent should be mdded in batches with heatlng and stirring in between rather than all at once. Hydrochloric acld attacks thorium vigorously but a mysteri- ous black or blue-black residue remains on completion of the reaction. As mick as 25 percent of the original metal may be comverted to the black solid by either dilute or concentrated hydrochloric acid. Most or all of this resl- due can be dlesclved by adding fluoride lon 1n small concentration to the hydrochloric acid. The blaeck réesidue may be ThO or it may be a hydride Thgz For a further discussion of this material see Katzin , James and Stresumanis-, and Katz and Bea:borgh. | | Thorium oxide targets csn also be dissolved by a mixture of hydrochloric acid plus (Nflh)z BiF¢ or of mitric acid plus (Hflh)zflfli‘G. A good discussion of the fluoride ion catalyzed dissolution of thorium metal or thorium dioxlde is given by Schuler, Steahly and Stoughton.'® 2. 8oluble Salts of Thorium Since thorium exists in solution as a comparatively small highly charged cation, it undergoes extensive interaction with water and with many anions. There 1s one great simplification in the agueous chemlstry of thorium in that it hes only one oxidatlon state and hence oxidaetion-reduction reactions do not need to be considered. The water soluble salts of thorium include the nitrate, the sulphate, the chloride and the perchlorate. 3. Ingoluble Balts of ThoriuméPrécipitation and Coprecipitation Character- isties of thorium The common Iinsoluble compounds of thorium are listed in Table 1. An inspection of the table suggests a number of precipitates which may e sultable for the removal of tracer amounts of thorium from solutlon. Good descriptlons of the insoluble compounds of thorium and their use in analysis are glven in the general references listed 1n Part I. Thorium hydroxide is a highly insoluble compound forming s gelatinous pre- cipitate when alkal! or ammonium hydroxide 1s added to an aguéous solutlon of Th*h. It 15 not amphoteric. Thorlum hydroxide dissolves In aquecus solutlions contalning ions such as clitrate, carbonate, or sulfosallcylic acid which complex thorium lon. Tracer amounts of thorium will coprecipitate quantitetive- ly with a wide variety of lnsoluble hydroxides; lanthammm, ferric snd zircon- TABLE 1 IRSOLUBLE COMPOUNDS OF THORIUM Reagent Precipitate Solubllity in Solubility in Water other Reagente OH ‘Th(OH), very insolgBle soluble in acids, S.P. = 10~ ammonium oxalate, alkall carbonates, sodium cltrate, etc. F ThF), - hnéo very insoluble soluble 1in acld aluminum nitrate solution Kr + HF KzThFG very lnscluble Io3' Th(103)4 very insoluble (even in strong EN03) soluble with reagents whlch destroy 103 C,0,= Th(Czoh)EGHEO ingoluble in water soluble in excess or 1ln dilute acid ammonium or potasslium oxalate PO, = Th3(P04)h very insoluble diesalves with difflculty in Th(HPOh)zHéo concentrated acid (PO, ) 5, PO; 22,0 BP0~ ThP_0, - 2H_0 extremely insoluble 276 : 276 Hz 1.65x10=*% moles per liter 4.ON HC1 H;0, + Th(00)230£3320 very insoluble soluble in strong 0.1X stoh mineral ecild TARIE 1 (Cont'd.) Reagent Precipitate Solubility in Solubility in . Water . other Reagents 503= Th(SO3)2H20 partially dissolved in excesa sulphite Cr207= Th(Cro,, ), * 38,0 insoluble 1n'320 . soluble in conc,acid Th(0H) ,Cr0, *E,0 MoQ, = Th(moh)zlmzo ' insoluble soluble in dilute mineral acids Fe(CH) gh ThFe(CN) 6-hELzO very insoluble ium hydroxide bhave been used. Since hydroxide carrier precipitates are notori- ously non-specific, they should be counted on only to remove thorium from e simple mixture of contaminants or as a group separation to be followed by more specific chemlcal purificatlon steps. In some of the classical studies of the uranium series’ le(Th23h') wag separated from uranium by precipitating ferric hydroxide and ammonium uranate together and leaching the uranium from the pre- cipitate with ammonium carbonate. Thorium peroxide forms when hydrogen peroxide is added to a dilute miner- al acid containing thorium. It is highly insocluble. The formula ip often glven &s Th,on but recent investigations suggest that anions are incorporated into the solld as integral components. The preclse formula of the precipitate varies with the condltions of precipitation. The physical form 1s aleo greatly different depending on the acidifiysa: when preclpitated from a neutral solu- tlon it 1s gelatinous and contains many copreclipltated anions; when preclipi‘ba'bed from a slightly baslc solution, it i1s not so gelatlnous and has & lower perox- ide content; when formed in an acid solution, 1t is opaque and readily filtered. Insoluble peroxide compounds are rare in the Periodic Syst. 8o that preclplta- tion of thorium peroxlde can provide clean separatlion of thorlum from most other elements. Plutonium (IV) forme & peroxide similar to tbat of thorium (IV). Other (IV) state elements such es cerium (IV) and zirconium (IV) aleo form such in- soluble peroxides. Urenium (IV) and neptunium (IV) also form insoluble precipi- tates upon the addition of peroxide, but these seem to be of a somewhat differ- ent type than those formed by thorium and plutonium. These peroxide precipl- tates are reedily dissolved by the addition of reagents such as Sn(II), I, MRop or Ce(IV) which can destroy peroxide. For a more complete discussion of the peroxide and for references to the original literature, see Katz and Sea- borgs. Lanthamm Fluoride as Carrier for Thorium. Thorium will coprecipitate quantitatively with lanthamm precipitated as the fluoride from strongly acidiec solutions. This is e very useful method for the aeparation of small smounts of p thorium from uranium sclutions. The fluoride may be converted to the hydroxide by direct metathesie with mlkall hydroxdde pellete or strong alkall solutions, or it may be dissolved in an alumimum nitrate-nitric acid solution (which thoroughly complexes the fluoride ion) and then be precipitated as the hydroxide, The coprecipltation of rare esrth impurities 1is, of course, complete. Zircon- l1um and barium in trace concentrations are carried but, i1f milligrem quantities of these elements are added as "hold-back carriers”, no coprecipitation is ob- served. Hence coprecipitation with lanthamum fluoride serves as an excellent method of freeing thorium from the zirconlum carrier used lIn a previous step. An slternate method would be the removal of zirconlum on an anlon exchange regin from an 8-10 molar solution of hydrochloric acid. Other lnsoluble fluorlides may serve as carriers for trace amounts of thor- ium. Zirconium Todate as Qarrier. Zirconium in a cohcentration of 0.1 to 1.0 'mg/ml may be precipitated as the iodete from a strongly acidic solution to carry thorium nearly quantitatively. The iodate concentration is not critical. Elements which form insoluble lodates are also coprecipitated, but many, such as uranium, are separated. The rare earths and actinium are decontamlnated if the preclpitation i1s from a strongly scidic solution and the preclpitate is washed with an lodate contalning selution. Under conditions of low acldity and low total ionic strength, the carrylng of these elements may be gulte high, as shown for actinium by McLane and PetérsonT. If cerium is present 1t 1s necessary to reduce Ce(IV) to Ce(III) with eome sulteble reducing egent such as hydrogen peroxide, before precipitation. The zirconium lodate may be dissolved in nitrilc acid containing sulfur dioxide or some other reducing agent, and the zirconium may be repreclpitated as the hydroxide after the solution 1s boliled to remove ilodine. Hegemann and his co-m:rkerea8 applied this method to thelr study of the isotope T]:x229 in the 4n + 1 series. Their procedure is reproduced in Proced- ure 16 of Section V below. Ba.lloru9 used 1t as a means of substituting zircon- lum carrler for rare lea.rth carrier after an 1nitial leanthanum fluoride precipl- tation. See Procedure 13 in Section V below. Phoephate Precipitates. Thorium precipitates in a varlety of ill-definped forms in the présence of phosphorous-containing enions. These compounds are extremely insoluble in.water and in acid solutlion. The hypophosphate is parti- cularly insoluble. Even in @i Hecl the solubility is only 2.1 x lf)ll' moles per liter. Other insoluble phosphates such as zirconium phoephate serve as good carriers for the removal of trace amounts of thorium from-agueous esolution. Thorium Oxalate. A widely used method of quantitatlive analysis of thorium is the precipitation of thorium oxalate followed by ignition to thorium dioxide and weighing of the dioxlde..° Some camplexing agents lnterfere with the precipitetion of thorium oxalate by the formation of soluble thorium complexes. Gordon and Shaver report a& meth- od for the separation of rare earth ions from thorium by precipitation of- phos- phate-free rare earth oxalates l1n the presence of the strong chela.ting a.gent, ethylenediaminetetraacetic acid (EDTA). _ "Organic Aacids which form water-insoluble compounds with thorium vhich are of possible analytical or radiochemical importance Include sebacic, a.nthranitic, phenylarsonic, galllic, tennlc, quinaldic and aspartic acids. 4. Complex Tons of Thorium - The highly-charged pceitive lon, Th+‘h, has & strong tendency to form com=- plex ions with enions which may be present in solution. Some familiarity with the more common of these complex ions is required for a proper u.nderstanding of tbe behavior of thorium lm ion exchange sepa.ra.tions, in the extraction of thori- um into organic solvents and so on., Quantitatlive measurements which have been made on the equilibrium constants for complex ion formations are summarized in Table 2. TABLE 2 COMPLEX IORS OF THORIUM (Reprinted from Katz and Sesborg p.57, reference 5) Complexing Reaction - Ionic K I Ref'- Agent 8trength _ erences c1L” 01" = e *3 ' 0.5 2.2h a 0.7 1.78 a 1.0 1.53 a 2.0 1.21 e 4.0 1.70 a 6.0 2.1 a mn*te2cT = Thcféz 2.0 0.1 a Yo - 0.1k a 6.0 0.55 a 301" = Tao1tt 2.0 0.2 . a - 4.0 0.10 a 6.0 0.35 a e = ThCL,, : k.0 0.018 a N05 Th*"‘mo; = Th(NO3)+3 0.5 L.73 b : ' 2.97 2.83 Th+h+2£0§ = Th(NO3);2 5.97 1.4 c c10; '1'h+4+01o; - 'I‘h(ClO3)+3 ~ 0.5 1.84 b TABLE 2 (Cont'd.) Complexing Reaction Tonic K Ref Agent ' Strength erences Bro; Th+h+Br05 = Th(Br03)+3 0.5 6.4 b ‘I‘h+h'+2:Br05 - Th(BrOB)'éz 0.5 8.2 b C1CE,COOH Th+h+ClCHZCOOH = Th(C1CH,C00 R 0.5 1.33 b C1,CHCOCH Th+h+CIZCBJOOH = Th(Clzcacoo)+3+H+ 0.5 5.7h b Th“‘+2012011c003 = Th(Clchcoo);2+zn* 0.5 12.7 b C1.,CCO0H Th+h+013CC00H = Th(0130000)+3+]1+ 0.5 8.23 b Th*l-tec13ccoon = Tl:\(c13ccoo)'2’2+13H+ 0.5 26.7 b 1'0_;’ Th*l‘qo; = Th( 103)+3 0.5 "{.6x_'|.0i b Th+l++2105 = Th(IO3)£2 0.5 6.2x10 Th+h'+310; = Th( :ro3)3JL 0.5 1.4x107 - +i - ++ -+ EOM_ Th +E0h‘ = ThSOh +H 2.0 159 .C Th*'!f-zmo; = Th(80,, ) +2E" 2.0 2850 c '1'?:1*"‘“+215|.°..o,:L = Th(rsohsoh)‘” +E" 2.0 800 c HaPoh_ Th#'t+H3PO,+ = Th(H3POL)+J+ 2.0 T8 ¢ Th+h+H3P01|_ = -1'1:1(15[2?01‘)"34[+ 2.0 150 c Th+4+ZH3POh_ = Th(HzP°hH£°1+)+3+H+ 2.0 1400 c Th*‘l‘+zna1=oh = Th(H,P0, )5 +2H" 2.0 8000 c EF Tt EF = ThETO4E 0.5 sx10° o T4 2HF - ThF§2+ZH+ 0.5 2.9,‘10; e e 3EF = ThF3+3H+ 0.5 9.4x10 d CH,COCH, COCH, Tht*+EAcAc = Th(ache)t+E" 0.0l 3. 7107 e Tt +2BAcAc = Th(AcAc)*Zr2E" 0.0L 7.3kx10%? T, 3pAcAe = Th(AcAc) +3H" 0.0L 5.93x10%° Th“AEAcAc = -Th(AcAc)ll_+1+3+ 0.01 5.3Tx1025 a. W.C. Waggener and R.W. Stoughton, J. Phys. Chem . 56, 1-5 (1952). b. R.A. Dey Jr. and R.W. Stoughton, J. Am. Chem. Soc. T2, 5662-66 (1950). c. E.L. Zebroskl, H.W. Alter, and F.K. Heumann, J. Amer. Chem. Soc. T3, 5646-50(1951) - d. H.W. Dodgen and G.K. Rollefson, J. Am. Chem. Soc. 71, 2600-7 (1949). e. J. Rydberg, Acta Chem. Scand. 4, 1503-22 (1950); Arkiv for Keml 5, 413-23 (1953). - A large number of other complex ions are known although not much quantita- tive information 1s avallable on the strength of the complexes. Ions derived from meny organic acids such es cltrate, phthalate, maleate, succinate, malo- nete lon and ethylenediaminetetrascetic (called EDTA or versene) form a series of complex compounds or lons with thorium, The soluble EDTA-Complex of thorium . forms the basis of an excellent tdtrimetric determination of small amounts of thoriumll’lz. It 18 of great significance to radlochemistry that thorium forms a negatively-charged nitrate complex in nitriec acid solutions greater than 3 molar in concentration. This is discussed further in connection with anion exchange methods. In connectlon with complex ion formation we may mention briefly the hydroly- sis of thorium ion. In acidlic solution throughout the entire range below pH3 hydrolysis of Th+1|. is negligible. At higher pH values there is extensive hydroly- 8le. There is a consldersble disagreement in the published literature on the | products of hydrolysis end a number of mononucdlear and polynuclear complexes have been postulated. For interesting experimental studies and theoretical in- terpretation of the hydrolysls of 'I'h+h see Krans and Holmbergl3 and Ei]_'l.énlh’ 15. 5. Chelste Compounds of Thorium A few 1,3 diketones form chelate complexes of thorium which are readily ex- tractable from agqueous solution into organic solvente. This fact forms the ba- gls of a wildely used method for the radiochemical purification of tracer thor- ium, namely the extraction into benzene of the thenoyltrifluorcacetore acid com- plex of thorium which 1s discussed in section 6. Before discussing this speci- fic eystem, it will be worthwhile to review briefly the other known complexes of this type which thorlium forms. The very strong and rather volatile complex of thorium.with ecetylacetone has been knwon for many yea.rs.ls In a 1,3 diketone complex of this type, four molecules of the organic compound react with the Th'm ion to form a neutral complex. Thorium acetylacetonate, like the other metal acetylacetonates, poeges a cyclie structure with the metal incorporated as part of a six-membered ring. Rydberng has made a particuarly careful study on the complex formatlon between thorium end acetylacetone and of the extraction of the complex 1lnto organic solvents. Other 1,3 diketones which form similar complex compounds mich more stable toward acidlc solutions are trifluoroacetylacetone, thenoyltrifluoro- -2 acetylacetone, benzoylacetone and dibenzoyl 11149.'t.]:ua.1:LelB 0._ A comprehensive 1n- 2 vestigation of thorium chelate complexes was carrled out by Dyrssen 1. Some of his remults are quoted i1n Teble 3 where the complexing constants of the proton and thorium complexes of several chelating agente are given. Thorium forms complex compounds with salicylic acid, methoxybenzolic acid and cinnamie acidzz. The thorium-salicylate complex extracted lnto methyl isobutyl ketone has salicyclic aclid assoclated with 1t and mmy have the formila Th(HA)h-HzA. Cowan®2® developed a procedure for thorium analysis based on the extraction of the thorium salicylate complex into a mixed solvent of chloroform " and ethyl acetate. ‘ | Cupferron (nitrosophenylhydroxylamine) forms & complex which can be ex- tracted into cholorform. Thorium forms a complex with quinolinol which is sol- uble in orgaenic solvents.23 The thorlum complex wilth the reagent, thorin, 1s widely used in a colorimetric analytical method.23a’23b TABLE 3 THORIUM COMPLEXES OF SOME CHELATING AGENTS. (Dr:rflsenZJ) Chelating Agent: DKa 1/4 log X (note 1) Acetyl acetone 8.82 -2.85 Thenoyltrifluoroacetone 6.23 . +0.0k4 1-nitroso-2-naphthol T.63 -0.41 2-nitroso-l-naphthol 7.24 +0.05 Tropolone 6.71 +0.52 Cupferron 4.16 +1.11 N-phenylbenzohydroxamic acild 8.15 -0.17 8 Hydroxy quinoline (oxine) 9.66 -1.78 5 Methyl oxine 9.93 -2.5 5 Acetyl oxine T-75 -1.0 5,7 Dichloro oxine T4 =0.22 Cinpamic acld 4,27 notel K= [MAnJ orgfif]n [M]n[HA]grg , where MAn = uncharged complex; [BA]= ec1d form 6f the chelating agent. 6. Extraction of the TTA-Complex of Thorium into Organic Solvents Many of the chelate complexes mentioned in the last section of this report are soluble in organic solvents. By sultable adjustment of reagent concentre~ tions and acldity, thorium cen be cleanly separated from conteminating ione by such an extraction procedure, We single out for special attention the complex formed with a-thenoyltrifluoroacetone, (called for convenience, TTA), which has been more widely used in rediochemlistry then any of the others. Some of the reasons for this are the gtabllity of the reagent toward acidic solution, the favorable Keto-enol equilibrium in the remgent, the strength of the thorlum com- plex in slightly acldic solutions and the moderate solubllity of the complex in such solvents as benzene, chloroform and ketones. Hagemannah studied the zcld dependence of the extraction of trace quantities of thorium, ectinium and other elememts into an 0.2M solution of TTA in benzeme. A typlcal curve 1s shown in figure 1. The extraction of thorium is essentially quantitative ebove pHland drops rapldly in solutions of higher acidity. The acld dependence is fourth power so that rather sensitive control of the extrac- tiofi can be made by control of the acldity. This control 1s highly useful since thorium mey easily be separasted from elements of lower lonic charge such es the alkall elements, the alkgline earths and even the rare earth elements by extrac- tion of thorium 1n the pH range of 1 to 2. Elements which extract more readlly than thorium are left in the benzene phase when the thorium is later removed by contact with an agueous solution. of sl ightly lower pH. The chief lomns which are extracted more strongly than thorium Iin solutions of acidity greaster than pHL are zirconium (IV), hafnium (IV), plutonium (IV), neptunium(IV), iron III, and protactinium (V). These ions show high partition coefficients into the organic phese for solutions as strongly acidic as 1 molar or greater. Further control of thorium extvrectlon can be achieved by chenging the con- centration of TTA or by using another solvent In place of benzene. The presence of ions which form strong complexes with thorium (see Table 2) interferes with the extraction of thorium; therefore, it is best to perform the extraction from S — 100F 2 i Th(lV) Ac (I11) o 80 |— xX 60 ' w MU-9899 - 40+ w 20F (& ES I i 1 ! i 1 a i 2 3 4 5 6 7 8 pH Figure 1 Extraction of trace amounts of actinium end thorium from a dilute nitric acid solution by an equal volume of an 0.25 M gdolution of TTA in benzene as a function of pH. a8 dilute nitric acld, perchloric acid or hydrochloric acid solution. Most of the complex ion formation constants listed in Table 2 were measured by noting the changes in the extractability of the thorium-TTA complex into benzeme when various anions were added. to the agquecus phase. Hence the references quoted in Teble 2 can be consulted for very specific information on the extraction of thori- um in the presence of complexing anions. TTA extraction of thorlum is an important step in several of the procedures written down in SBection V below. Thorium may be separsted from uranium when both are present in small con- centrations 1if the solution co.nfa.ins no great quantity of neutral salts, but the acldity mist be edjusted carefully, There are better methods for meking this particular separation. The extraction of tracer thorium from concentrated golutions of uranium is not satisfactory beceause of the formation of insoluble uranium complex compounds at the interfece and it is necessary to remove the bulk of the urmalum by some prelimlinary step. In the isolation of small emountes of thorium from a complx initial mixture of elements TTA extraction provides an excellent final step. Carrier precipitates such as lanthanum fluoride and zirconium lodate may be used to remove the bulk of the impurities and the finel purificaetion as well as the elimlnation of the carrier material, may be effected by a final TTA-extraction cycle. The solubility of the thorium-TTA complex In benzene 18 rather small so that large volumes of solutlon are required to handle bulk amounts (gram amounts) of thorium. Some .wor]a:ersz5 report good results with the reagent, 1-(3,4 dichloro- phenyl) - &,k4,5,5,6,6,6 heptafluoro-1,3 hexanldione which forme a thorium complex with a coneldersbly higher solubility in benzene. Unfortunately, this reagent is not avallsble commercially. With this ‘reagent 20 grems of thorium can be dis- solved 1n 100 millileters of Cfllh_ compared to 0.3 grems of thorium as the TTA- complex. T. Extraction of Thorium Into Organic Solvents o The extrzctability of thorium from esgqueous solutlions irto organic solventa has been studled for dozens of representative solvents of all types. Most aof these studies have been concerned with hydrochloric acid systems, nitric acid syetems or mixed nitric acid - neutral nitrate salt systems. A great deal of the information on the extraction of thorium, urenium and plutonium was origj.- nally published in dlessified repfirts of the Manhattan Project or of the Atcmic Bnergy Commission or of the governmental lsboratories of Canada and Great Britain and France. This information is now declassifled, but there has never been a complete systematic covermge of the basic chemistry in bocks &nd Journals readi- ly avallable in any sclentific laboratory. Solvent extractlon processes have been developed for the recovery of thorium from monazite sands, for the separa- tlon of U°33 from neutron irradiated thorfum, for the recovery of the irraiisted thorium for reuse, and for othefi:- .purpoaes. In this brief review, we conflne our rema.rks to the chief solvents and the pflnc:l.pa.l effects of experimental conditions of the laboratory scale treatment of small or tracer quaht:l.ties of thorium, Ethyl ether ig often used to purify uranium. If the agueous phase ia slightly acidic with nitric acld (perhaps .0l to .05 Molar) and highly selted with a neutral nitrate such as amnnium, cdlclum or megnesium fiitrate, then 12 uranium ieg reedlly extracted into ethyl ether leaving nearly all lmpurities in- cluding thorium in the aquecus phase. Thorium will not extract into ethyl ether unless the concentration of acid ard neutral salts in the aqueous phase is so high that numerous other Impurites would also extract. Methyl iscbutyl ketone wlll extract thorium with a distribution coeffi- clent ae high as 9 (organic/aq_ueoua) provided the nitric acld concentration of the agueous phase 1s malntgined at 1M to 3M and if, in addition, a high concentration of such strong salting egents as calelum, magnesium or aluminum nitrate 1s maintelned. At the Towa State College in Ames Iowa, large quantities of thorium were purified from monazlte sands by a process which included a sol- vent extraction separation of thorium fram rare eexrth impurities 26. The so0l- vent was hexone and the aquecus phase feed solution was 3 Molar in calcilum ni- trate and 3 Molgr in nitric acid, _ Rydberg and Bernstrim’| have studied the distribution of Th(IV), U(VI), Pu(IV), PU(VI), Zr(IV), Ca(II}, La(III) and mwo3 between methyl isobutyl ketone and agueocus solutions of nltric acid and calcium nitrate of varying composition. Figure 2 teken from thelr work shows the maln feamtures of the extractlon of theee 1lons. A 1955 Geneva Conference peper of BrucezTa discusees the extractlion of flssion products into hexone. Pentaether (dlbutoxytetraethylene glycol) will extract thorium from equeous nitrate soclutions under moderate salting conditionasz. For example, 3 and 1M or greater in calclum nltrate are removed to the extent of 90 percent or more from the agqueous phase by an equal volume of this solvent. Fifty percent is removed from s IM B.ND3 solution and 80 percent from an BM BNJ3 solution by an equal volume of solvent. If the agueous phese ig 1M in H'.NO3 arzag saturated with emmonium nitrate, the extraction 1s quantitative. Pappard ~ hes reported the use of pentaether 1n the purification of lbnium (Th230) from pltchblende resldues. He states that 90 percent of the thorium is extracted from a solution &M in “Eum3 and 0.3 M in HFO_ into an equal volume of solvent consisting of a mixture of pentaether (2 volumes) and diethylether (1 volume). Under these conditipne less than 1 percent of yttrium snd the rare earths are extracted.See alpo analytical method of nefigseffgfi oxtde [ (CB,), C = CH-CO-CH3] has been reported to be & useful sol- vent for thorlum. Levine and Grima.ldizg have used 1t in an analytical procedure tracer amounts of thorium in a solutlon Zy_ in HRNO for the determination of thorium in thorium ores. The ore sample is decomposed by fusion wilth a mixture of NaF 'KZSZO'T' Thorium is precipltated as the oxalate. The oxalate preclpitate 1s dissolved 1n nitric eclid end the solution 1s pre- pared for solvent extrection by edjusting the ZE[BOB concentration to 1.2 Molar and edding eluminum nitrate to 2.5 Molar, The solution is contacted with an equal volume of mesityl oxlde which extracts the thorium quantitatively and separates it from nearly all impurities including rare earths. Traces of 13 - = L o L Lo MU - 16989 LJ o o < o = = < o K o= 000" 1 1 ] | 4 5 6 | M HNO, Figure 2 Solvent extrection data for methyl isobutyl ketone. The distribution ratios of U, Pu, Th, Zr, La and Ca as functions of the equllibrium concentration of HN03 in the mqueous phase, Concentration of Ca(NO is 3.5 to 4.0 Molar. Data by -Ry'd'berg w27 and Bernatrom. 3)2 rare earths are removed from the solvent by three separate washes with e wash solution containing HNO &nd Al(ND ) . The thorium is stripped from the washed - solvent with weter. Thorium is precipita'ted as the oxalate and ignited to Tth, in which form 1t 1s weighed, Hiller and Mertin3® have used mesityl oxlde to extract thorium eway from rare earth fission products in a thorium target solution. The thorium metal was dissolved in HC1 with a small amount of fluosilicate lon present to clear up the solution. The solution was seturated with A1(®O )3 and the thorium was extra.cted. by contecting the solution with mesityl o:d.d.e. Marechal-Cornil and Picciotto3 used mesityl oxide for the quantitative .ex't.ra.ction of thorium, bismth and polonium from a mixture of natural radlo- elements present in concentrations 10_9 grams per c¢.c, The solution was sat- urated with Al(N03)3. Redium and lead did not extract. Tributyl Phosphate (THP) 1e a wldely used solvent in the industrial scale recovery of uranium and thorium from ores, or the purification of urenium, thor- ium or plutonium from reactor fuel elements. Some idea of the scope of 1ts use 4 32-34 can be obteined by consulting some general references on process chemistry. The mdjustment of egqueous phase composition for the optimum radiochemlcal purification of thorium depends greatly on the nature of the impurities present. The principal heavy elements or fission products which show high extractability into TBP are the following: thorium (IV) < £¢ptunium (I¥) < plutonium (IV) plutonium (VI) < neptunium (VI) < uranium {VI) protactinium (V) cerium (IV) hafnium (IV) zirconium {IV) rare earths (ITI) (considersbly less extracteble than above under most cond:l.'l:.ions). RuNo (III) TABLE 4 BASIC REPERXNCES ON THE EXTRAOTIOF OF THORIUM, OTHER HEAVY ELEMENTS AND THE RARE BARTHS INTO TBP Tri-n-butyl Phosphate as an Extracting Bolvent for Inorganic Nitrates, I. Zirconium nitrate 35. K. Alcock, F. C. Bedford, W. H. Hardwlick and H.A.C. McKay, J. Inorganic and Nuclear Chem. L4, 100, 1957. II. Yttrium and the lower lanthanide nitrates 36. D. Bcargill, K. Alcock, J. M. Fletcher, E. Hesford, and H.A.C. McKey. J. Inorg. Fucl. Chem. L4, 304, 1957 ITT. The plutonium nitrates _ 37. G. F. Best, H.A.C. McKay and P.R. Woodgate, J. Inorg., Rucl. Chem., k%, 315, 1957 IV. Thorium nitrate 38. E. Hesford, H.A.C. McKay and D. Scargill, J. Inorg. and Fucl. Chem. 4, 321, 1957 An excellent overall view of the extraction of these elements from hydro- chloric or nitric acid systems of varylng composition into an undiluted or diluted THP solvent phase is presented in the articles listed in Table L. The high extractabillty of thorium into undiluted TBP from hydrochloric acid and nitric acld systems are given in figures 3 and 4. Thorium nitrate 1s mich more extractable when most of the nitrie acid in the esgueous phase 18 re- placed by some nitrate salt such as sodium nitrate, caleium nitrate or alumlmum nitraete. Thls 1s drematically shown 1n Taeble 5 where some date taken from a publicetion of H.A.C. MKay are presented. The maln reason for the difference 1s that the neutral nitrate salts are not soluble in TBP whereas BNQ3 forma a seoluble complex with TBP. Bernstrom and Rydberghl have studied the effect of the replacement of HN03 with calcium nitrate on the extraction of thorium by undiluted tributyl phosphute. An approximate summary of thelr results 1s glven in Table 6. Some of the impor- 0.} 0.01 0.001 1 1 1 1 20 4.0 6.0 8.0 10.0 120 M OF HCI 1 0.0001 o . Figure 3 Variation of distribution ratios (TBP/agueous) of gcandium, thorium and zirconlum with aqueous HC1l concentratlon for extraction into pure, undiluted TBP. Peppard, Mason and Maierhz. tant separations which can be made with such a mixture of "salting agents" in the - aguecus phase are apparefit from an ipspection of figure 5. The viscosity and denslty of undiluted TBP mekes 1t somewhat troublesome to use, Hence 1t 1s frequefitly diluted to a 10 to 40 volume percent solution in some inert diluent solvent such as n-butyl ether, ether, benzene, carbon tetra- chloride, kercsene or some industrial mixture of hydrocerbons., The diluted THP extracts thorium with & reduced extraction coefficlent but, as a cqmpensatory change, the ektractability of a number of other ions 1s reduced below the point where they will extract to an apprecisble extent, Thorium may be recovered from a TBP phase into an aguecus phese by back- washing the TBP with dlstlilled water or with very dilute acid. 16 100 K 10 1.0 0.1 Q 2 4 6 8 i0 12 14 16 M OF HNQ3 Figure L Variation of distribution ratice (TBP/aqueous) of scandium, thorium and zirconium with aqueous HNOa concentration for extraction into pure undiluted TBP. Peppard, Mason and Maierhz. 17 — < wJ o L L Ll o & =2 10 o = T L HNOs L 5 9211232 %;> 901‘]:1228. It 1s possible to standardize a solution of Th228 by allowing it to . decay untll all its daughters are at equilibrium, then alpha counting it and subtracting the contribution of the rest of the decay chain. It 1s, however quicker and more reliable to mix accurately-measured quantities of Th22é and a known Th230 solution, fume with Hflloh, and then separate ' from daughter activities with an AG 50-XL column ag in Step 9 of the regular fission product purification. The resultant plate 1s pulse-analyzed to get the ratio of Th228 to Th23° which, when multiplied by the alpha count of Thzao, gives the correct alpha count rate for Th22 . If this tracer is to be used for an apprecimble length of time, a decay correction for its 1.9 year half-1ife will have to be made. There is another correction to be made in pulse analyses involving 228, me energy from 4,66 of the alphas of the RaZ2% gaughter of ThZZ8 coincides with the amlpha pesk of Tho20. The time of last separation of the daughter is noted. This 18 the time when the last HC1l wash comes off the last AG 5o-xh column. ' This parent-daughter relationship falls imto the clessification of tran- 8lent equlilibrium, where the equation of radicactive decay is simplified to ‘the Pollowing: . . _l—::lI ME h- L0 Né(t) = (e "PROCEDURE 9 (Cont'd.) 224 8 vhere the subscript 2 refers to Ra and 1 refers to Thzz . N; is constant for the times involved, so it is convenient to make up a plot of sznf against time using the above equation. The elapsed time from the end of the BEC1l wmsh on the last cation exchange column to the midpoint of the pulse analysis 1s noted on the curve, the fraction Hz/N; read from the gmph, multiplied by 0.046, and subtracted from the counts under the'Th228 peak. To get the countlng rate of Th230 in a sample with 'I'h2 ‘tracer,.the ratio of the Th23°/'.1:h228 peaks is multiplied by the alpha counting rate of Th228 as obtalned above. 28 S5A. Procedure for Thorium Isctopes in a Solution of Fission Products Step 1. Pipet the tracer into an Erlenmeyer flask of the proper size; use a 50-ml flask when the volume of sample plus tracer is less than 10 to 15 ml; a 125-Erlenmeyer for 12 to 50 ml. Plipet the sample into the flask, using a clean plpet for each sample o that the sclutlon will not become contemineted wvith the tracer. Add a few drops of .Fe carrler (carrier sclution 10 mg iron per ml) and sbout 1 ml of conc. HC10). Evaporate to demse vhite fumes and con- tinue heating for at least 2 minutes after their first appearance. This evaporation 18 most rapidly done over & Fisher burner, but if there is no hurry it may be done using an air Jet and either a hot plate or an oll bath. Cool and add 10 to 15 ml of HZO and transfer to a short-taper LO-ml centrifuge tube. There may be a fine-gralned residue of 8102 in the Erlenmeyer, but thorium loss at this point is not very great. Step 2. Add an excess of conc. NELOH, mix well, centrifuge, and discard the supernate. Step 3. Dissolve the precipitate from Step 2 in 1 ml of 3M HC1 and dilute with Hzo to half the volume of the tube. Add conc. NHhOH to precipitate the hydroxide, centrifuge, and discerd the supernate. Step L. Dissolve the precipitate from Step 3 in about 5 ml of 3M HCl. If there is a very heavy precipitate of FE(OE)3, it may be necessary to add more 3M HCl to obtain complete solution. Again ignore a small residue of SiOz. Prepare a column 0.6 cm in diameter and eabout 7 cm in height filled with AG 50-X4, 50-100 mesh resin. Pour the HC1l solution onto the top of the resin and allow to run through by gravity. Wesh the column with 10 ml of 3M HC1l and discard both the wash and the firset effluent. Put a 50-ml Erlenmeyer contain- ing 1 ml each of conec. HCth and HN03 under the column and add 3.5 ml of O.5M 15[20201\L to the top and gllow this to pass through by gravity. Step 5. Evaporate the solution from Step 4 to dense white fumes and con- tinue heating for about a minute. | La PROCEDURE 9 (Cont'd.) Step 6. Transfer the solution to a 40-ml long-taper centrifuge tube and rinse the contents of the flask into it with 2 ml of comc. HCl. Add 2 to 3 drops of 0.5M NaBr03 and saturate wlth HC1l gas whlle the tube i1s surrounded by water at room tempersture. Prepare a wash solution by adding a few drops of NaBr03 to conc. HC1l and saturate it at the same time. Step 7. Prepare two colummns for each sample. The diameter of each column is 0.6 cm and each 1s filled to a height of ebout 7 cm '-r.Lth AG 1-X8 or AG 1-X10, 100-200 mesh resin. Add the Bolutio:; from Step 6 to the top of one of the columns and collect the effluent 1n a dry centrifuge tube. Rinse the origipal tube and columm with about 1.0 to 1.5 ml of the wash solution prepared in Step 6. Combine this wash with the effluent end pass through the second column. Rinse thie in the same manner as the firat and collect the combined effluents in a 50-ml Erlenmeyer. It may be desirable to use very light air pressure to push the solution through these two columns. ' Step 8. Evaporate the solution from Step 7 to 2 to 3 ml and add 1 ml of conc, J:INO3 and 0.5 ml of conc. HIJJ.OL, and continue heating until dense white - fumes mve been evolved for about a minute. Cool and add 2 ml of water. Step 9. Prepare a column 0.35 cm by sbout 7 cm filled with 100-200 mesh AG 50-X} resin. Pour the solution from Step 8 on the top of the column and force it through with light pressure (2 to 3 1b). Wash the columm with 4.5 ml of 6M HC1 and discard this wash and the first effluent, Add 0.3 to 0.k ml of Q.5M Hzczoh and push down _the column with very slight pressure. Make sure that the leading edge of the oxalic acid band does not get to the bottom of the resin and get discarded wlth.the other effluent. Add 0.7 ml of O,.5M HZCZOlL to the top of the column and collect the sample on a 5-ml Pt plate. If it is for alpha counting only, use a 1-3/h" to 2" diameter plate. If beta counting is to be performed also, the sample is collected on a 1" diameter plate. The sampleée ere dried under heat lamps and are left there untll most of the Hzczoh is sublimed. Then they are heated to red heat in a flame. SB. Thorium Procedure for Coral or Limestone Samples Step 1. Dissolve 100 to 125 g of coral (accurately weighed) in 250 ml of conc. ]5|1!03 and make up to 500 ml with HZO. This gives a solution contalning about 0.2 g of coral per ml. ' Step 2. Add a 50 ml allquot of the well-mixed solution to a 90-ml cen- trifuge tube together with 1 ml of Thzah (see Section 5C) tracer solution end 1 ml of Fe carrier. Stir and heat in hot water bath for an hour; then cool (Fote 1). Step 3. Add cone. NH)OH slowly with stirring until IE':.E(‘.'J.E)3 precipitates and then centrifuge for 5 minutes (Note 2). 42 PROCEDURE 9 (Cont'd.) Step 4. Decant and dissolve the precipitate inm 5 ml of come. HN03, dilute with H20, and again precipitate Fe(OE)3 with conme. RHhO . Step 5. Centrifuge, decant, and dissolve the precipitate in 5 1 of conc. HN03’ and with HZO wash the solution into a Pt dish. Add 10 ml of conc. H \h and 5 m! of conc. HF. Step 6. Take to fumes of HDth three times, washing the sides of the dish with water after esch fuming (Note 3). Step 7. Dilute the HCth solution to gbout 25 ml with HZO' Step 8. The first columm (4 x 150 mm with 40-ml reservoir) is filled with an AG 50-X4, 200-400 mesh resin-water mixture and packed to about 120 mm. Wash the resin with 3M HCth and add the solution from Step 7. Allow to flow at atmospheric pressure or adjJust the pressure to give a flow of about one drop every 30 sec. | . Step 9. When the solution reaches the resin, add 3M HCL acid in several l-ml portions, washing down the sides of the columm. Continue until the ferric chloride color disappears. Step 10. Elute the Th with 0.5M H,C,0, (2 to 3 m1), catching the effluent in a centrifuge tube. Add to the HZCZO,l solution 5 ml of comnc. HN03 and 5 ml of conc. H.ClOl+ and teke to fumes of HCth three times, washing the beaker down with H O after each fuming (Note 3). Step 11. Add the solutlon, diluted with EZO to 12 ml, to the second colum (2 x 150 mm with a 15-ml reservoir) packed to & length of 120 mm with the seme resin and treated s in SBtep 8. Adjust the flow rate as in Step 8 also. Step 12. When the solution reaches the level of the resin, wash with five 1-ml portions of 3M HCl, rinsing the sides of the centrifuge tube with each portion. : ' Step 13. Elute the Th with 0.5M Hzczoh, collecting the first ten drops of EZCZOh acid effluent on a Pt plate. (The first few drops which are HCl are not collected.) Evmporate to dryness under a heat lamp, and flame. Step 14. Count Th23h to determine the yleld and pulse-snalyze the alpha radiation (Notes L =snd 5), — Additional Reagents and EBquipment for this section are: Dowex 50-X4, 200-400 mesh Resin columns - 4 x 150 mm with a 40-ml reservolr 2 x 150 mm with 3 15-ml reservoir Rotes 1. The phosphate, chloride, and other impurities in the coral and the high acid concentration seem to take the thorium into a completely exchangeeble form. ' 43 PROCEDURE 9 (Cont'd.) 2. Large quantities of phosphate increase [Ca3(POh)2] is precipitated along with Fe(OE)3 end lead to a decrease in yleld due to the formation of phosphate complexes of thorium. . 3. The solution 1s fumed three times to be sure no fluoride or oxmlate 18 there to Interfere 1n separation. 4. The isotopic thorium composition 1s calculated from the growth and decay of alpha activity. 5. The yleld for this procedure variles from 50 to 90%. 5C. Isoclation of Thorium Decay Products from Large ‘@Quantitles of Uranlum Parent 23 and Th23h decay. For preparation of tracer using either of these thorium lsotopes, the final step is an AG 50-X4 cation exchange column as in the determination of comnting efficiency of Tho3* or Th23* under Section 4, except that the Pinal oxalic acid effluent is fumed nearly to Aryness ?1th 1l ml each of conc. HEO3 and HCth. If an emount of uranium up to ebout a gram 1s sufficient to supply the amount of tracer needed, the AG 50-Xk column can be used as in Sectiom &, except that the final oxalic acid effluent is fumed nearly to dryness with 1 ml each of conc. EHO3 and BCth. 1s sufficient to supply the amount of tracer needed, the AG 50-X4 column can be ueed ae in Section 4. B8ources of Th23l or Th23h can be milked from a 'cow' of the appropriate uranium isotope asdsorbed on an AG 1-X8 column., The uranium 1s isoleted from a solution of oralloy, approximately 93.5% U235, is obtained from normal urenium end the Th231 present allowed to "If an amount of uranium up to about a gram is dissolved 1n conc. HCl, and some oxlidizing agent such as bromate ion or bro- mine water or chlorine gas 18 used to oxldize the uranium to U(VI). The golution is then saturated with HCl gas at room temperature and adsorbed on an AG 1-X8 column. For 10 g of uranium a colum aout 25 mm 1n dlameter and holding 150 to 200 ml of resin bed is satisfactory. The resin is pre-washed with conc. HCl containing about 0.5 ml of 2M laIBrO3 per 100 ml of acid. The uranium solution is pareed through the column and thén re-cycled two or three times to get more of i, adsorbed. Then the column is washed with about twice the resin bed volume of conc. HC1l containing a drop or two of the bromate solution. After a sultable growth time for the thorium daughter, the colfimn is treated with conc., HC1 as above. The solution is evaporated to a small volume, fumed with 1l ml each of conec. HR03 and ECth and treated with an AG 50-X4 colum as in Section 4. A Th23l source reading over 1 roentgen was prepared from 2 kg of oralloy as follows: the uranium metsl was dissclved in an excess of conc. 4 PROCEDURE 9 (Cont'd.) HNO3 and this solution was evaporated until the temperature became constant at about 118°. This is the boiling point of WO (NO ) - 6H 0. This solution freezes at about 60 , 80 1t can be cooled to 70 to 800 and the molten hexmhydrate poured into a 5-liter separatory funnel containing about 3 to L4 liters of diethyl ether that is being rapidl& stirred with an air-driven stirrer. This must be done in a good hood with explosion-proof fixtures, or out of doors. As long es the molten hexahydrate is added in a slow stream to the ether with good stirring, ‘the operation is perfectly safe and the ether losses are rnot too large, since the vapor pressure of the ether decreases rapidly as the uranium is dissolved. It 18 a far-mdre rapld and easler operation to add the molten hexahydrate than it 1s to c 'ystallize it and &d4d the crystals. The final golution in ether from the 2 kg of oralloy should have a volume of sbout L liters. An aqueous layer of about 600 ml is withdrawn. The ether solution is scrubbed with three 3-ml ‘portions of H_ O to insure complete removel of any thorium that might be present. Tthl is allowed to grow for 1 to 2 days and then 1s removed with three 3-ml portions of HEO' This aqueo':: layer is shaken with two 200-ml portions of ether to remove more of the uranium. The residual water layer 1s first evaporated on a steam bath to remove ethér, then fumed with 1 ml each of conc. ENO3 and ECth and the AG 50-X4 column used as in Section 4 except that the column dimensions are 0.2 cm x 5 cm. The bulk of the Th231 can be followed down the column with a beta-gamms survey meter and over 80% of it is usually concentrated in 2 to 3 drops. The oxalic acld effluent is placed in small drops on & 10-ml Pt wire about 1.5 in long and the wire gradually heated to red heat by applying e current, controlled by a Vériac. In this way the oxalic acid is completely volatilized, leaving a nearly mass- free depoeit of Th23l. The ether 'cow' of uraenium can be kept over s eeverail week period for the preparation of & number cf éanples. PROCEDURE 10 Source - R.J. Prestwood in "Collecdted Radiochemical Procedures"” Los Alamos Report LA-172l. Jan. 1958 l. Introduction In the separation of thorium from large amounts of fission products (1015 fissions or more), four principal decontamination steps are employed: (1) Th(IO )h precipitation gives separation from the rare earths. (2) 'rh(c2 ) precipitation effects separation from zirconium. 45 PROCEDURE 10 (Cont'd.) (3) Ion exchange from a concentrated (greater than 12M) hydrochlaric acid solutlon on a Dowex A-1 anlon resin results in the adsorptiom of zirconium, iron, neptunium, nlutonium (VI), and uranium (VI}, the thorium passing through the column. (4) Extraction of thorium from ¢ aluminum nitrate - nitric acid solution by means of mesityl oxide ((cn'3)2 C =CH. - E - 033) glves excellent deccontamination from the alkali and alkaline earth metal ions (including radium), lantfianum, and cerium. This e: ‘raction is lneffective for the separation ¢~ thorium from zorconium, plutonium (VI), and uranium (VI), and gives only poor decontamination from neptunium. | Thorium is finally precipitated as the oxalate and ignited to the dloxide, in which form it is mounted and weighed. The yleld is TO to 80%, and quadrup- licate analyses can be carried out in approximately 8 hours. 2. Reaggnta Th carrier: 10 mg Th/ml (See preparation and standardization of carrier). Bi carrier: 10 mg 31/m1 (added as 31(:03) "5H,0 in dilute nno3) La carrier: 10 mg La/ml (added as La(no3)3-sgzo in néo). Zr carrier: 10 mg Zr/ml {added as purified.ZrOClz'Bflio in nzo). HCl: conc. HIO.: 1M (carefully filtered). HC,0,: saturated solution (carefully filtered). EHlI_OH: conc. HCl: gas. EBS: gas. 502: gas. 2.4M A1 (H03)3 in 1.2M 13103 (carefully filtered). IC103: 80ligd. Methanol: absolute. Mesltyl oxlide: Eastman White Label. 3. Equipment 3team bath Fisher burner PROCEDURE 10 (Cont'd.) Drying oven Ignition furnace (900°) Block for holding centrifuge tubes Forceps Mounting pletes Ground-off Hirsch funnels Filtef chimneys Transfer pipets Manifold for column pressure 60-ml separatory funnels (one per sample) 40-ml conical short taper centrifuge tubes: Pyrex 8320 (four per sample) LO-ml conical long taper centrifuge tubes: Pyrex 8140 (one per sample) 2", 60° funnels Stirring rods (5 mm glass rod) Stirring rods (4 mm glass rod - hooked end) 10-ml hypodermlc syringes Porcelsin crucibles: Coors 000 (one each per standardization ani sample) No. 42 Whatman filter circles: 15/16" dlameter No. 50 Whatman filter circles: 15/16" diameter - weighed No. LO Whatman filter paper (9 cm) Fo. 42 Whatman filter paper (9 cm) Jon exchange column 3" x 5 mm tubing attached to bottom of 15 ml centrifuge tube 4 cm of Dowex A-1 anion resin, 10% cross-link (about 200 mesh). The resin 1ls suppllied by Bio-Rad Labcratories, 800 Delaware, Berkeley, California. The resin 1s stored as a slurry in water. To prepare the ion exchange columm, plug the bottom with glass wool, then add the resin slurry from a transfer pipet. Allow the resin to settle and withdraw excess resin and liguii. It i1s important that the resin be added all at once, and not by several additions of slurry, to avoid "channeling®™ down the columm, 4. Preparation and Stendardization of €Carrier If the purity of the thorium 1s known, the metal may be weighed out directly as a primary standard. It is dlssclved on a steam bath in a small excess of concentrated HIO3 In a Pt dish, with perlodic additions of small amounts of O0.1M HF. If thorium nitrate is used as carrier, i1t is 8issolved in about 0.00LM HNO, and filtered. To & 10.00 ml aliquot (four standaraizations &7 PROCEDURE 10 (Cont'd.) are usually carried out) of the carrier, 10 drops of cone. HCL are added and the solution is boiled over a Fisher bturner, Four ml of staurated Hzczoh are then added and the solution 1s bolled for 2 min. The thorlum oxalate pre- cipitate is filtered through No. L2 Whatman filter peaper (9 cm) in a 2", 60° funnel and washed with sbout 1 percent H2020h solution (the saturated sclution 18 diluted 1 to 10). The precipitate 1s transferred to a tared porcelain crucible (Coors 000) and is carefully igrnited at 9000 for 1 hour. The carrier 1s weighed as ThOz. 5. Procedure Btep 1. Into a LO-ml short taper centrifuge tube, pipet 2.0 ml of standard Th carrler; add the fission product solution and 5 drops of La carrier. Precipifate Th(OH)h by means of an excess of conc. REhOE, centri- fuge, and discard the supernate. Step 2. To the precipitate add 8 ml of conec. HNO3, 15 ml of HEO’ and 7 ml of 1M EIO3' Centrifuge the Th(103)h preclipitate and discard the supernate. Wash the precipitate with 15 ml of a solution which is LM in HNO_. and 0.25M in HIO 3 Centrifuge and discard the supernate. Step 3. To the precipitate add 1 ml of canc. HCl and 5 drops of Zr hold- back carrier. Heat with stirring over en open flame until the precipitate dissolves and the solution bolls. Dilute to 5 ml and bubble in SOz &a8 until the solution becomes essentially colorless. Dilute to 10 ml and boil until the solution is water white. Add 4 ml of saturated HZCZOL soluticon and continue bolling for about 1 min. Centrifuge the oxalate precipitate and discard the supernate. Step 4. To the precipitete add 1 ml of conc. HIIO3 end about 100 mg of solid KClOS. Heat cautiously to bolling to destroy oxmlate. Dilute to 15 ml and precipitate Th(OH)h by means of an excess of conc. NH,OH. Centrifuge and 3 discard the supernate. Step 5. Add 10 drops of conc. HCl to the precipitate and bubble in HCL gas through a transfer plpet until the solution 1s saturated. With the aid of a8 hypodermic syringe and the same pipet, transfer the solution (which hae a volume of epproximately 1 ml) onto a Dowex A-1 anion reein (10% cross-link) column (Before uae,'the resin column is treated with a wash solution made up by adding 1 drop of come. HRO3 (Note 1) to 20 ml of conc HCl end saturating with HCl gas at room temperature.) By mesns of air pressure , force the eample solution through the columm in approx;mately 3 min, but do not ellow the meniscus tc go below the top of the resin. The effluent 1s collected in a 40-ml short taper centrifuge tube. Add 48 PROCEDURE 10 (Cont'd.) 1l ml of the resin wash solution to the original centrifuge tube and transfer the washings by means of the same pipet onto the column. The vashings are forced through the column in the same manner as the semple solutiofi, and are collected along with the sample solution. This wesh - ¥y be rep- *ed. Step 6. Dilute the collected samp.. plus washes to ap~—oximately 25 ml and make the solution basiec with conc. NH&OE. Centrifuge the Th(OE)h precipi- tate end discard the supermnate. Step 7. Dissolve the precipitate with 6 drops of M E ‘3. Use 10 ml of 2. M Al(N03)3 - 1.5M HNO3 mixture (hereafter called the extraction mixture) to transfer the sample solution to a 60-ml separatory funnel. Add 10 ml of mesityl oxide to the separfitory funnel , shake for 15-20 sec, and discard the water (lower) layer. Wash the mesityl oxide layer twice with 5-ml portions of extraction mixture, discarding each washing. Back-extract the thorium with two 5-ml washes of distilled EZO’ collecting both'EZO layers ;n a 40-ml short taper centrifuge tube. Dilute to 15 ml and add 8 m of conc. HR03 and 7 ml of 1M HIO (Note 2). Centrifuge the Th(IO3)h precipitete and wash as in Step 2. Step 8. Repeat Steps 3, 4, 5, and 6. Step 9. To the Th(OE)h precipitate, add 5 drops if Bl carrier amnd 10 drops of conc, stoh' Dilute to 10 ml and saturate the solution with st. Filter through a No. kO Whatman filter paper (9 cm) in a 2", 60° funnel, collecting the filtrate 1n a 40-ml short taper centrifuge tube. Wash the pre- cipitate with a small emount of water and combine the wash with the filltrate; discard the precipitate. Make the filtrate basic with conec. NHhOH, centrifuge, and dlscard the supernate. Step 10. Repeat Step 7. Step llf Repeat Step 3, but do not add Zr holdback carrier and do ndt centrifuge the oxalate precipitate. Step 12. Filter the hot solutlon containing the oxalate precipitate onto a 15/16" Ko. 42 Whatman filter circle, using a ground-Hirsch funnel and filter chimney (see illustration 2). Wash the precipitate with 1% Hzczoh solutlon. Transfer the filter paper by means of forcepe to a Coors 0O0Q porcelaln crucible and ignite for 15-20 min at 900°. Step 13. Tranmsfer the Thoz to a dry Lo-ml long taper centrifuge tube. (This is readily done by holding the edge of the cruciblée with forceps and dumping the contents Into the centrifuge tube. TLittle or no 'I'hO2 edheres to the crucible.) Grind the ThO,, Witk a 5 mm fire polished glass stirring rod; 6dd 1 ml of absolute methanol end continue grinding until the sclld is very fine. Add an additional 10 ml of methanol and suspend the solid by vigorous swirling. Transfer onto a tared No. 50 Whatman filter circle (15/16" diameter) 3 k9 PROCEDURE 10 (Cont'd.) in the regular filter chimney setup. Apply suction until the_fiethanol has passed through the filter circle. Remove the circle, dry in an oven at 115o for 10 min, place in the balance case for 20 min, and welgh. Mount the sample on two-sided Scotch tape which is stuck to an Al plate. Cover the sample with Nylon £ilm (1.5 mg/cmz). Notes l. The purpose of the HN03 1s to maintain an oxidizing medium on the resin to prevent reduction of Pu(VI). _ 2. At this point the solution will be somewhat colored as a result of oxlidation of dissclved mesityl oxide. This, however, does not affect the results. 6. P-Counting of Th Whenever Th B activities such as isctopes 231, 233, and 234 are cbunted and Th232 is used as carrier, one 1s faced with the problem of the growth of pB activities from the carrier. Examination of the decay chein of Th232 shows that the amount of p actlivity depends upon the quantity of Th228 present. In the chain the longest lived parent of Th228 (half-1ife 1.9 y) is Razze the ’ half-life of which is 6.7 y. Thus, the amount of Th228 present in 232 depends upon the time of separation of 35228. The B emltters succeeding Th228 grow in 224 essentially with the half-1ife of Ra which 1s 3.64 4. Therefore, the B actlvity that one observes from natural Th which has had all of 1ts decay products chemically removed grows im with a 3.64 d half-life. One mg of natural Th in equilibrium with its decay producte has 494 disintegretions per minute ° B activity. Since cne does not usually know the history of the Th used as carrier, the moest convenient way to correct for these coun.. is the fo' owing: Pipet out as much carrier solution as will glve approximateiy the same welght ae & true semple would when carried through the whole separation procedure. Perform Steps 9 through 13 of the procedure. Note the time of the laest mesliyl nxlide "msh of Step 10. After the sample is mounted, count 1t every few hours over & period of several days. It 1s convenient to use the time of he last mesityl oxlde wash as t . In thls manner, one can correct for the growth of betas from the carrier. The counting of 'I'hz31 is rather 3ifficult because of 1its weak B radiastilons [0.302 (u4%), 0.216 (11%), 0.09% (L45%)]. This. isotope has nine y-rays ranging in energy from 0.022 to 0.230 Mev. Since the efficiency of y-counting, even with 1 in. Nal crystals, 1s quite low, one usumlly counts the betas. This means that extreme care must be taken to insure uniform thickness of samples. Th233 and Thzah do not present such difficulty. The former has a 1.23 Mev p and decaye 20 PROCEDURE 10 (Cont'd.) to Pa”J> which has a 0.530 Mev B. The latter, although it has weak radiations, decays into Pa23h (1.175 m) which has a very strong B. 7. Absclute B-Counting of Some Th Isotopes The relation between counts and disintegrations for thorium isotopes of mass numbers 231, 233, and 234 can be cbtained from UE35, Np237, and U238, 235 238 respectively. If a weighed quantity of U or U is taken, Th carrier added, and a chemical separation of Th made, one can calculate in each case the number of Th disintegrations present. By counting the sample and correcting for decay from time of separgtion, one has a direct relationship between counts and dis- integrations. The self-absorption of the sample can be taken into account by the use of this technique on several different weights of Th carrier with identical specific activity. for example, one adds 100 mg of Th carrier to a weighed amount of either U235 or U238, mixes the solution thoroughly, takes several aliquots of different sizes, and separates the thorium. In this way, one can plot a curve of sample weight vs disintegrations. In the case of Th233 the sltuation is somewhat different. The decay product of this isctope is P3233} which is also the immediate decay product of Np237. By separating Pa233 from a known weight of Np237 and counting the former, one has a direct relationship for PBZSS of counts vs disintegratioms. For a sample of Th.233 one takes twe known aliquots, differing by a factor of about 1000 in activity. (The ratio of Pa’33 to Th23S half-lives if 1693.5.) The wesker aliquot is counted for Th233 immediately upon separation of Pa. The stronger one is permitted to decay until it is all P3233 and is then counted. From the previous (Np237) calibration one then can find the disin- tegrations of Pa233 for this sample. The sample is corrected for decay back to the time the weaker sample was counted for Th233, thus obtaining the number of atoms of the latter when the sliquot correction is made. PROCEDURE 11 Source - G.A. Cowan in "Collected Radiochemical Procedures” Los Alamos Report LA-1721. Jan. 1958 Preparation of Carrier-Free UXi(Th23h) Tracer 1. Introduction In the separation of le(Th23”) from uranium, the latter, originally present in the form of UOZ(NO3)2, is converted to a soluble uranyl carbonate complex by meaps of ammonium carbonate solution. Then at pH 8.0-8.5 the cup- 51 PROCEDURE 11 (Cont'd.) ferrate of uxl is made and separated from the uranium by extraction into chloroform. The UI_L is back-extracted into dilute nitrie acild contalning bromine which serves to decompose the le cupferrate, thus allowing extractlon of all the organic material and excess bromine int the chloroform phase, 2. Reagents z(15103)2: 1 g U ml. (Added as 1_1308 or 1102(1!03)2.6320 in dllute msoa). BN03: 3IM _ (NEH)ZCOB: saturated aqueous solution ]3:|:'2 wvater: saturated solution : , . Cupferron: &b agueous solution (freshly prepared and kept in refrigerator) Chloroform: c.p. Hydrion paper (short range) 3. Bguipment 250-ml. beakers (2 per sample) 250-ml. separator funnels (3 per sample) Volumetric flask: appropriate size (1 per sample) Plpeta: assorted slzes 1" cover glasses Heat lamp 4., Procedure Step 1. Pipet 10 ml. of uoa(uo3)2 solution into a 250 ml. besker and treat with saturated -(mik)aco3 solution end H,0 until the yellow precipitate vhich first forms dissclves. Sufficient (mh°z°°3 1s added to meke the final pH of the eolution 8.0-8.5 (Fote 1). ' Step 2. Transfer the solution to a 250-ml. separatory funnel, anl add 1-2 ml. of 6% aquecus cupferron reagent and 10 ml. of chloroform. Shake well . and transfer the chloroform layer containing the Ull To a clean separatory funnel. Repeat the chloroform extraction and combine the extracts. Step 3. Wash the chloroform extracts with 20 ml. of 1120 to which has been added 1 ml. of cupferron reagent and sufficlent (nx[h)zco3 solution to make the pH 8.0-8.5. Transfer the chloroform phase to a clean separetory funnel. Step 4. To the chloroform phase add 10 ml. of 3M B‘.l03 and a few ml. of saturated B:L-2 water and shake. Discard the chloroform phase and waah the agueous phage twice with chloroform, discarding the washings. Transfer to a 250-ml. besker and boil for a minute to remove the last traces of chloroform. 52 PROCEDURE 11 (Cont'd.) Transfer the solution to a volumetric flask of the appropriate size and make up to volume with HZO° Step 5. Pipet aliquots of solution to 1" cover glasses and evaporate t0 dryness under a heat lamp. Count, ' Rotes 1. A pH of 8.0-8.5 appears to be the optimum for the preparation and gxtraction of the le cupferrate, although a pH in the range 7-8.5 1s suitable. PROCEDURE 12 Precipitation Procedure for the PTeparatiai of Thorlum Free of its Disintegration Products. N.E. Ballou et al. Paper 225 in "Radlochemical Studies; The Fission Products" edited by C.D. Coryell and N. Sugarman, McGraw-Hill Book Co., Inc. New York, 1951. "o a solution of approximately LOO g of Th(NDB)h.hHEO one gram each of barium and lead (as the nitrates) was added and precipitated with an exactly equivalent quantity of stoh. This operation which removes the radium isctopes NBThl and ThX and the lead 1sotope ThB, was repeated; after the barium and lead preclpitates were flltered and discarded, 1 gram of lanthanum (as the nitrate) was added to the filtrate. About 3 liters of comc. (HHh)zCO solution was asdded; this precipitated the lanthanum and converted the thorium intoc a soluble carbonate complex. Lanthanum was precipltated from the 3 solution twice more by adding one gram portions of lanthanum. These precipi- tates, which remove the actiaum isctope MsTh2 (Hhoseichemistry is gquite similar to that of lanthanum), were separated from the solution by centrifugation. The purified thorium was then precipitated as the basic carbonate, ThOCOfi.xHBO, by the addition of about TOC ml of conmec. EHO3 and was filtered and dried.” FROCEDURE 13 Zirconium Iodate as a Carrier for the Removal of Tracer Thorium from Rare Earths. N.E. Ballou. Paper 292 in "Radiochemicsl Btudies; The Fission Products” edited by C.D. Coryell and K. Sugarmen, McGraw-Eill Book Co., Inc. Nev Yark, 1951. Procedure originally formulated in 1943. The starting solution contains a mixture of the flssion producte of . uranium and severasl millig-ams of rare-earth cerriers including Cerium(IIT). A mixed rare earth fluoride precipitate 1s formea oy the addition of 4M HF to 53 PROCEDUHE 13 (Cont'd.) a 24 3103 solution of the activities. Tracer thorium coprecipitates The fluo- ride precipltate is dissolved in canc. E!D3 saturated 53m . XC10,_ is added and the solution is heated to oxidize cerium to cerium(IV). Add 20 ml 0.35M E[Oa to precipitate Ce(IOa)L (vhich coprecipitates thorium). Diesolve the Ce(IOa)h in comc. no3 plus one drop of 30 percent H,0,. Add 5 miliigrams of lenthanum carrier and 2 grams of xc103 and reprecipitate Ce(IOa)h_. Dissolve the precipitate in 5 ml of conc. ma plus 1 drop of 30 percent 5202. Add 5 milligrams of zirconlum carrier and 20 ml of O.35M HIO3 s cool in ice and centrifuge to remove the precipitate of !'.r(IOa) j+ Thorlum tracer coprecipitates quantitatively. Cerium (et this point in the III state) 1s decontaminated by a factor of 200. For additional decontamination the Er(IOa)h can be dissolved in s mixture of hydrochlorlc acid and sulfur dioxide and the zirconium reprecipitated with naznroh. PROCEDURE 1k Source - L. Winsberg and J. A. Seiler. Paper 309 in "Radiochemical Btudies: The Fission Products" edited by C.D. Coryell and N. Sugarman, McGraw-Hill Book Co., Inc. New York, 1959. Original report written in 19L3. 1l. Introductiom The older procedure for the determination of mhzal‘(‘uxi) activity in fission meterial depended cn the separation of ThZ3" with the rare-earth fraction and on a later removal with thorium carrier. The procedure deac:r_i‘bed here_is much improved and shortened. Thorium is used as a carrler for its lsctope UX,. Thorium iodate, together with zirconium activity, precipitates from a come. Ema solution on the addition of 3103 , but the other fission products, including the trivalent rare earths (cerium 1s present in the reduced state), remain in solution. Thorium is then precipitéted as the oxnlate from a solution containing zirconium holdback carrier. Xrconium remains in salution as the soluble oxnlate complex. The thorium oxalate is ignited to the oxide, mounted, and counted for UI_L activity. 2. Procedure Btep 1. To an appropriate amount of uwanyl nitrate in a 50-ml centrifuge tube, add a known amount of thorium carrier (about 20 mg) and 10 mg each of cerium(IIT), lenthanum, and yttrium carriers (Note). Add 8 ml of canc. EIJB, varm on a steam bath, and stir 2u ml of 0.35M HIO3 into the solution. Recard the time of precipitation. The mixture is cooled in an ice bath with stirring. >4 PROCEDURE 14 (Cont'd.) The Th(IO3))_L precipitate (containing UX, and zirconium activity) is centrifuged and washed twice with 2- to 10-ml portions of a mixture of 4 mi of conc. HNO3 and 10 ml of 0.35M HIO3. Step 2. The Th(}:o3)lL precipitate is dissolved in 5 ml of conc. HCL, and 1C mg each of cerium(III), lanthanum, and yttr... carriers and 10 +- 5 ml of HZO are added. The centrifuge tube is placed * . ice bath, and SO2 is passed in to reduce the IOg to I and to maintain the cerium in the Ce(III) state. The sclution should be clear after treatment with SO2 fo several minutes. The solution is made alkaline with conec. NHAOH, and an excess is added. The hydroxides are centrifuged and washed twice with H20 to which a small amount of NHhOH has been added. Step 3. The hydroxides are dissolved in 8 ml of conc. HNO_, and an iodate separation is carried out as described in step 1. The Th(IO )h so cobtained is dissolved in 5 ml of conc. HCl, the 103 is destroyed with SOZ’ and the thorium is precipitated as the hydroxide, as described in step 2. Step Yy, The washed thorium (UXl) hydroxide, which still contains zirconium activity, is dissolved ir 6N HCl; 10 mg of zirconium carrier is sdded (Note); and the solution is diluted to 10 ml. Ten milliliters of hot saturated oxalic acid solution is added to the hot solution with stirring. The Th(czoh)2 pre- cipitate is centrifuged and washed twice with a 1 percent oxalic acid sclution. One gram of KClO3 carefully for a few minutes until gas evolution ceases. The solution is diluted to 10 to 15 ml, and Th(on)J+ is precipitated with conc. NHhQH and washed twice with H20 to which & small amount of NHhOH has been added. . Step 5. The hydroxide is dlssolved ir 6N HCl, 10 mg of zirconium carrier is added, and the solution is diluted tc 10 ml and heated in a steam bath. and 3 ml of conc. HN03 are added, and the solution is heated Ten milliliters of hot saturated oxalic acid solution is added to the hot solution with stirring. The 'l‘h(CZOM)2 precipitate is centrifuged and washed twice with a 1 percent oxalice acid sclution. The precipitate is then suspended in 20 ml of H_.O containing 0.5 ml of &N HC1l and a small amount of 2 macerated filter paper. The Th(CZOu)z precipitate is collected on an ashless filter paper in a small Hirsch funnel. The paper and the precipitate are transferred to a crucible, the precipitate is ignited to ThO_, and a weighed 2 sample of the oxide is mounted for counting. Note The carriers are prepared as slightly acidic solutions of the nitrates. 2> PROCEDURE 14 (Cont'd.) '3. Discussion Thie method was tested by analyzing both unirradiated and neutran- 1rradiated uranyl nitrate for Ufli._ The two analyses gave identical mctivities and absorption curves; thls indicated that Ull i1s obtained radiochemically pure by the above procedure. In the analysls of solutioms of high fission activity it may be necessary to repeat the thorium iodate and thorium oxalate precipitation gseveral times. PROCEDURE 15 Determination of Thzah(uml) Activity in the Presence of Uranium and Fission Products. K.E. Ballou and D.N. Hume. Paper 310 in "Radiochemical Studies: The Fission Products” edited by C.D. Coryell end N. Sugarman, McGraw-Hill Book Co., Inc., Rew York, 1951. It is based on report cn-i312 dated May 15, 1945. l. Introduction The precipitation of thorlum with HF and KF (prdbably as KzThF6) removes Thzah (Uxi) from uranium and the fission products except the rare earths, zirco- nium, and the alkaline earths. The addition of zirconium holdback carrier markedly reduces the coprecipitation of zirconium. Large amounts of UO';+ cause some UOZF2 to come down with the fluoride precipitawv.; this is re. 1y removed by washing the precipitate with €M HF. The golution of the thorium precipitate is accompliched by warming with HNO_ and H,BO,. The precipitation of Th(OH), removes the alkaline-earth con- tamination. Additional decontaminstion from all the fission products except zirconium end niobium (columbium) is brought sbout by the precipitation of .Th(IO3)h from & LM HN03 solution. The precipltation of thorium with oxmlic acid serves as an additional separation from zirconium and niobium and also converts the thorium to a welghable form. 2. DProcedure Step 1. To 5 ml or less of uranium and fission-product ple in e lusteroid tube, add 1 ml of conc. HROS, 20 mg of standard thorium carriler, and 10 mg of zirconium holdback carrier. Dilute to 20 ml and add 3 ml of conc. HF end 3 ml of €M KF. Centrifuge, and wash with 5 to 10 ml of &M HF. Step 2. Dissolve the precipitate with 2 ml of 6 percent H3BD3 and 2 ml of cone. HRO3 (Fote 1}. Dilute to about 15 ml, add 5 mg of parium holdback carrier, and precipitate with 3 to 4 ml of conc. NHMQE. Centrifuge, and wash with 20 ml 0. of H2 56 PROCEDURE 15 (Cont'd.) Step 3. Add-8 ml of conc. HNO3, 10 drops of 3 peréent HZOB, and 20 ml of 0.35M EIOB-to the precipitate. Cool; and let the Th(Io3)h precipitate . Jnd for 5 min (Note 2). Centrifuge. and wash the precipitate with 10 ml of & mixture of 3M HRO_ and 0.03M HIO.. Step 4. Dissolve the Th(103)h precipitate by the addition of 2 ml of conc. HCl, dilute to about 20 ml, and pass in SOz.until the solutlon becomes color- lees. Add 5 ml of conc. RE Step'5. Dissolve the hydroxide precipitate in 8 ml of conc. HN03, and add 5 mg of Ce(III) carrier, 0.5 ml of 3 percent 3202, and 20 ml of 0.35H'H103. Cool, and let the Th(103)4 precipitate stand for 5 min. Centrifuge, and wash with 10 ml of 0.035H.HIO3. Add 2 ml of conc. HC1l to the precipitate, dilute to 20 ml, and pass SOZ into the solutlon untll it 1s colcorless. Precipitate Th(OE)h by the addition of 5 ml of conc. RE,OH, and centrifuge and wash the precipltate with about 20 ml of EZO' 8tep 6. Dissolve the precipitate in 1 ml of 6N HC1l, add 15 ml of Ezo, heat the solution to bolling, and add 15 ml of sat. H,C,0,. Coal the Th(czoh)2 precipitate in an ice bath for 10 min, and filter it on a weilghed filter-paper disk. Wash with alcohol and ether, and use the same technique for drying and weilghing as in the rare-earth procedures (Note 3). Count without excessive delay (Note &4). hOH and centrifuge. -Rbtes 1. Additianal H3BQ3 and BRO_ may be mnecessary if much lanthanum was present in the original sample. 2. Hydrogen peroxide reducee cerium to the Ce(III) state, in which it is not precipitated from strongly ecid solutions by IO.. ' 3. The precipitate is welghed as Th(CZOL)z.BHZOn The carrier must be standardized in the same manner. k. The thorium precipitate should not be allowed to stand very long before the activity measurements are made, since the p-actlive disintegration 3 products of thorium contribute an incregsingly larger fractlon of the total activity with time. 3. Discussion The procedure has been tested by using carrier-free tracers of cerium, yttrium, rutheniufi, strontium, zirconium, and tellurium. The final thorium oxalate precipitate was contamineted to the extent of 0.06 percent of the grose added tracer activity. ' T PROCEDURE 16 Isolation of Th229 from a mixture of 0233 and 1its decay products by means of coprecipitation on Zr(IO3)lL and extraction with TTA. 8or—-= - Hagemsann and co-worke=-, Phys. Rev. T9, 435 (1950). One- to two-tenths of a milligram of zirconium nitrate end sufficient lodic acid solution to give a final iodate cancentration of 0.05M were added per milliliter of solution of U233 in O0.1N nitric acid. The precipitated zirconium iodate was washed by centrifugation, dissolved in sulfur dioxide- water, heated to remove llberated iodine, diluted, and the zirconium reprecipitated with lodic acid. Four to five of these cycles served to de- contaminate completely from urerium, radium, and most of the actinium. Bismuth and lead actlvitles were removed by ome or two lead sulfide by-product preclpitates. ' In order to prepare samples sufficilently free from carrier for alpha- particle range_méasuremefits in the pulse anelyzer, and to remove any traces of actinium activity, the following procedure was used. The thorium isotopes were co-preclpitated from the final zireonium iodate solutlon with lantlanum fluoride carrier (0.1-0.2 mg/ml), the fluoride precipitate was metathesized to hydroxide wlth concentrated potassium hydroxide and the hydroxide dissolved in 0.05M nitric acid. Separation of the thorium activity from the lanthanum carrier was accomplished by extraction with a solution of Q.15M thenoyl trifluoracetone (TTA) in benzene. The change'frdm zirconium to lanthenum carrier was necessary since the former extracte into TTA solution under the canditions used, whereas the latter does not. In some cases, TTA extraction of the thorium i1sotopes was made directly from the uranium solution. The TTA benzene solutlon was in either case evaporated directly on the counting plate or reextracted with 8N nitric acld and the latter solutiom evaporated. Ignition of the resulting ple .3 left an essentially weightless film of the thorium activity. PROCEDURE 17 Measurement of thorlum isctopes in sea water. Source - F.F. Koczy, E. Piceciotto, G. Poulaert, and 5. Wilgain, Geochim. et Cosmochim Acta 11, 103-29 (1957); see also Nature 17L, 742 (1953). Abstract In order to study the geochemlstry of thorium lsotopes in the hydrosphere, perticularly in the ocean, a method has been worked out by which Th232, Th23o, Th228, an 22t can be determined separately. Eight samples of 20 to 40 liters 58 PROCEDURE 17 (Cont'd.) of sea-water, from 23.0 fi to 34.97 % salinity, were collected in November 1953, in the Skagerak and the Gullmarfjord (Sweden). Thorium was isolated by the following procedure: Just after collection, the samples were brought to pE 2 and a glven amount of Th23lL ( ) was added as tfacer, Thorium was first precipltated with Fe(OH)3 as carrier. Further purification was obtailned by ion- exchange column chrometogrephy followed by solvent extraction; the final fraction was obtained as the cltric complex, a form suiteble to incorporstion in the photographic emulsion. The total yield varied from i to 23% according to the sample, as determined by the P activity of the tracer. The various Th isotopes were measured through their @ activity, using nuclear photographic epul- sions, more precisely the double-emulsion teéhnique. RdTh and RdAc both genersate five-branched stars; more than 90% of these originated from RdTh, as indicated by the length of the tracks: while Io and Th only yield single tracks of range 18.8 p and 15 p respectively in the emulsion. Most samples showed a much 1+ :r activity than expected; this did not make it possible to discrimirnate bétveen Io and Th through the range distribution of their tracks, thus we could cnly ascertaln upper limits of Io and Th concentrations. ' PROCEDURE 18 Preparation of UX absolute p-counting standards. OSource - T.B. Rovey, D.W. Engelkemeir, apd P.W. Levy. Paper 9, pp. 114-121 in "Radiochemical Studies: The Fission Products"” edited by C.D. Coryell and K. Sugarman, McGraw-Hill Book Co., Inc. 1951; report originally written in 1945, UX Standard. Pure U308 more than 3 yr old was dissolved in acld to meke a solution of sufficiently high concentration so that aliquots to glve m desired activiiy were large enough to permit accurate pipetting. The uranium concentration chosen was 4 mg/ml. Fifteen milliliters of this solution then gave an activity of about 9,000 counts per minute (c/m) at the highest geocmetry factor used. ' The uranium was precipitated from this volume with bese, and the pre- cipitate was dissolved in 1 ml of acid solution and transferred to a 3-ml lusteroid test tube. This transfer caused no detectable loss. Lanthanum carrier (0.25 mg) was added and precipliteted with KF. The precipitate was centrifuged out and washed twice with water. The supernatants were collected and tested for UX loss by LaF 1l to 2 percent. The first LBF3 precipitate was slurried with 10 pl of water, transferred to a sheet of 0.2-mil aluminum weighing 1.4 mg/cmz, end evaporated to dryness separation. The activity loss here was fisually 3 29 PROCEDURE 18 (Cont'd.) vith an infrared lamp. The lusterold tube and the transfer pipet were rinsed out with several 25-ul water washes, which were added to the rest of the precipltate and dried. A drop of dilute Zapon lacquer was evaporated on top of the precipitate. The lusteroid was then ashed, mounted; and counted. OCne to two percent of the total activity usually remained in this residue. The source then conslsted of about 0.5 mg of precipitate on an area of 0.4 cm2 mounted on thin aluminum. Thls sheet was attached with Scotch tape over a l-in. hole in an aluminum éard of conventional size, 2-1/2 by 3-1/h by 1/32 in. Four standards were made this way; the total mctivity of any one standard corrected for the €wo losses veried from the average by no more than 0.8 percent. ' PROCEDURE 19 Source .- G.R. Choppln and T. Slkkeland Scheme for the Separatinn of the Elements Francium Through Uranium. The separation is accomplished by three ion exchange column elutions, the first two utilizing Dowex-1 gnd the third, Dowex-50. Reaggnts 1 M FH,EF,, 0.5 M BF, 0.1 M EC1, 9 ¥ HC1, 0.1 M HC1-0.1 M EF, 9 M HC1-1 M FEF, 8 M HNO hnflnoy'analnmo : 3’ 3 Procedure .l. Prepare the first anlon resin column by paesing the solution of NEfiHFz through it to convert the resin to the fluoride form. A glass column which has been coated with paraffin before addition of resin is used. The resin bed in all three columns 3 mm x 5 cm. This of course is governed by the amount of material to be sorbed. A flow rate of 1.5 minutes per drop is used. (a) Load the sample in 1-2 drops of 0.1 M HCI1. (b) Begln elution with 0.5 M HF. Fr elution occurs immediately (first column volume). (c) After 4 or 5 colum volumes, elute with 9 M HCl. Ra, Ac, and Th, elute in next few column volumes. (d) The third eluting solution 1s 9 M HCl-1 M HF which elutes Pa immediately. ' (e) Finally U is removed by elution with O.1 M HC1-0.1 M HF. 60 PROCEDURE 19 (Cont'd.) 2. The second anion resin column is prepared by washing with 8 MZHN03. (a) The Ra, Ac, Th fraction is loaded and eluted with 8 M HN03 for several column volumes. Re and Ac elute immediately. (p) 1 M HN03 is used as eluant to remove Th. 3. The cation resin column is prepared by passage of 4 M'HNOB. (a) The Ra, Ac fraction is loaded and elution begun with L M Em03. Ra is eluted. (b) After elution of Ra, 8 M HNO, 1s used to bring off Ac. 3 Discussion From the characteristics of the elutlon peeks from the fluoride columms, it seems more likely that negative flucride complexes are sorbing rather than that insoluble fluorides are precipltating in the resin. The behavior of Ra is surprilsing as formation of a negative complex seems rather unlikély and Ban 1s not particularly insoluble. It has been suggested that Ra may be coprecipitat- ing with Can which is much more insoluble. PROCEDURE 20 Radiochemical Determination of ITonium in Uranium Fluorination Ash Source: F. L. Moore, Anal. Chem. 30, 1020 (1958) - Introduction Recent detectioufi‘ of iocnium (tl/z’ 8 x th years, 4.68 Mev alpha emitter) in process solutions of uranium "ash" from various gaseous diffusion processes pecessiteted an analytical method for the determination of this radiocactivity. Many of the process solutlons contain aluminum, lron, stainless steel corrosion products, fluoride, uranium-234 end -238, neptunium-237, and plutonium-239. The present method (60) for the radiochemical determinaticn of the thorium isotope, thorium-234 (le), in the presence of uranium and fission products. is satisfactory, as the gamma radiocactivity may be counted efficlently in the presence of the thorium carrier prescribed. However, a earrier-free method was desired for the determination of ionlum to avoid self-absorptlon losses of the alpha particles. The method for uml does not provide for the séparation of neptunium and plutonium. A method for the determination of fonium in coral 61 PROCEDURE 20 (Cont'd.) limeatone63 appears rather lengthy, because both enion and cation exchange steps are necessary to eliminate the plutonium interferencea The radiochemical method descrlbed gives satisfactory results on uranium ash process solutions. Mbat interferences are eliminated by a combination of lanthanum hydroxide and fluoriae_precipitations which carry the ionium quantita- tively. Uranium, neptuniumiand:plntonium are .effectively eliminated by maintain; ing them in the fluoride;soluble aexivalent oxldation state. The lanthanum fluoride technique 1is an-adaptation of the famllier method‘aof carrying plutonium (III IV) in the presence of plutonium (VI) Iron (III) forme e fluoride soluble complex and is essentially eliminated in this step. A final ert.raction6l of the ion-ium with C.5 M Z-thenoyltrifluoroacetone-:qvlene eliminates the lanthanum. oarrier, increasea the selectivity, and provides a polld-free plate for alpha counting Procedure Pipet a suitable aliquot of the sample aolution into & 5-ml Pyrex Brand 8060 centrifuge cone. Add 0. l ml of. lanthanum carrier (5 mg. per ml.) and mix well with 8 platinnm stirrer | Adfl l ml. of 19 M sodlum hydroxide, mix well, and digeat for 5 minutea_at room temperature. Centrifuge in e clinlicagl centrifuge for 3'minutea. Remove the.aupernatant aolution with mild suction. Wash the nrecipitate by stirring with 2 to_3 ml. of 0.05.5 sodium hydroxide. Centrifuge for 3 minutes, remove the supernatant solution, and repeat the wash step. | Dissolve the precipitate 1n several drops of concentrated nitric acid and "add 8 to 10 drops in excess. Add 0.3 ml. of O.4 M potassium dichromate, mix . well, and digest for ld minutes In a beaker of water at approximately bolling temperature.- Add 0.3_ml. of 2T M hydrofluoric acid, mix well, end digest at room temperature for Sfminuteal' dentrifuge for 3 mlnutes. Add 0.05 ml. of lanthanum carrier and atir the aupernatant solutlion, being careful not to dis- turb the precipitate Digeat for 5 minutes at room temperature. Centrifuge FROCEDURE 20 (Cont'd.) for 3 minutes and carefully remove the supermatant solution, leaving sbout 1 drop. Wash the precipitaté by stirring with 0.5 ml. of 1 M hydrofluoric hcid- 1 M nitric acid containing 1 drop of 0.4 M potassium dichromate. Centrifuge for 3 minutes, remove the supernatant solution, and wash the precipltate with 0.5 ml. of 1 M hydrofluoric acid-1l M nitric acid. Dissolve the lanthanum fluoride precipitate by adding 0.5 ml. of 2 M aluminum nitrate and several drops of 1 M nitric acid. Cerefully transfer the sclution to a 10-ml. beaker using several distillled water washes. AdJjust the PH to 1.4 to 1.5 with a pH meter and extract for 10 minutes wilth a ope-half volume portion of 0.5 M thenoyltrifluoroacetone-xylene. After centrifugation, evaporate an aliquot of the organic phase on s platinum or stainlesgs steel disk, fleme to a red heat, cocl to room temperature, and count in a proportional alpha counter. An alpha energy analyzer is useful for occasionally checking the disks, when pmall amounts of lonium are determined in the presence of high levels of other aipha radloactlivities. If radium, protactinium, americium, or curlum is not present, omit the final extraction step. Blurry the lanthanum fluoride precipitate with several drops of 1 M nltric acid and transfer quantitatively to a platlnum or stalnless steel disk. Rinse the cone with three 3-drop portions of distilled water, transferring the rinses to the disk. Dry under an 1lnfrared heat lamp, flame to a red heat, and count the disk In a proporticnal alpha counter. . The initial hydroxide precipitation nay.be cmitted 1f the sample solution does not contain aluminum or chromium. Discussion The procedure described ylelds 97 3% on process solutions. Most losses are in the pH adJustment prior to the final extraction. By rinsing the centri- fuge cone with several distilled water washes before pH ad]Justment and by using several portions of the organic phase to wash the beaker afterwvards, essentislly quantitative recovery of ionium can be effected. Quadruplicate analysis of a 63 - PROCEDURE 20 (Cont'd.) dilute nitric acid solution conteilning 1.4 x 10° alpba counts per minute per milliliter of ionium gave 99.h, 98.0, 98.1, and 99.5% recovery, which is satisfactory for a carrier-free technique. The radlochemist may desire tc apply a8 yleld correction fér the ionium recovery, particularly if many chemical separations are performed. The beta, gamma emitter, thorium-234 (le), is very fiseful in such cases. | ' The major alpha radioacti#ity present in this particular process was neptunium-237 along with much smaller amounts of plutonium-239 and uranium-234 and -238. Decontaminatipn from theée alpha emitters wae satisfactory. A solutlon containing 2 x 105 alpha counts per minute per milliliter of neptunium- h alpha counts per minute per milliliter of ionium was analyzal 237 and 5.6 x 10 by the prescribed procedure. An alpha energy analysis of the final plate indicated pure ionium with no neptunium-237 detected. This analysls should be performed occaslonally, if very low levels of lonium are being determined in the presence of high concentrations of other aipha emitters. Although radium, polonium, protactinium, americium, and curium were not detected in solutions of this particular process, these elements are often present in uranium wastes. Radium will be eliminated in the hydroxide precipitation and traces that do carry will be elimipated verj effectively in the final extraction of ionium.2 Deconéamination of ionlum from polonium was excellent: 0.02, 0.03, 0, 0.03, and 0.02% in five expériments. Solutions containing 7.6 x 10“ alpha counts per minute per millilliter of polonium-zoa were analyzed using the ionium procedure.' Analysis of the variofis separated fractions in the procedure indicated that easentially all of the polonium was in the oxidized supernatant solutian from the lanthanum fluoride precipitation. Thus, polonium behaves like uranium, neptunium, and plutonium in the procedure. As quadrivalent polonium readily carries on lanthanum flucride from nitric acld solutlon, the polonium may be in the sexivalent fluorlde-soluble state in the presence of potassium dichromate. Approximately 50% of the protactinium originally present remained in the supernatant aolfition as a Ffluoride soluble complex upon the pre- 64 PROCEDURE 20 (Cont'd.) cipitation of lanthanum fluoride. If protactinium-231 1s present, the lonium should be stripped from the 0.5 M 2-thenoylfrifluoroacetone-xylene By etirring with an equal volume of 2 M nitric acid for 5 minutes. Iocnium strips quantite- tively, leaving the protactinium In the organic phese. Typlcd decontemination . data for protactinium in four experiments (imcluding the final strip with 2 M nitric acid) gave 0.03, b.ZO, 0.07, and 0.05%. A ZM nitric acid solution con- taiging 6.5 x lO5 gamma counts per minute per milliliter of protactinium-233 was analyzed 1n 1l-ml. aliqpota.br the lonlum procedure. The final 2 M nitric acid gtrip solutlon was counted for protactinium-233 gamma redicactivity using e scintillation counter having s sodium icdide crystel. Although 1t 1s rarely necessary, the last traces of protactinium mey be removed by re-extracting the 2 M nitric acld strip solution with an equal volume of 0.5 M z—thenoyltrifluoro; acetone-xylene for 5 minutes. Americium and curium ere readily eliminated elomg with the lanthanpum carrier when the lonium 1s extracted with thls reagent. The method should prove useful in the carrler-free isolation of thorium isotopes. Although the procedure has been used specifically to determine lonium in uranium flaorination ash, it should be useful for the determination of ionium in various waters end rocks. Ionium may be isolated from compiex mixtures of elemeqts by lanthanum hydroxide and fluoride carrying, followe. by extraction with 2-thenoyltriflucroacetone-xylene. In analyzing materials con- taining natural thorium, a final alpha energy anaslyslis should be performed to differentiate lonlum from other thorium isotopes. 65-66 REFERENCES 1. W. M. Latimer, Oxidetion Potentials, 2nd Bi., p. 299, Prentice-Hall, New York, 1952. 2. L. I. Katzin, "Recent Developments in the Chemistry of Thorium”, Paper 7/731|-, Proceedings of the Internatlonal Conference on the Peaceful Uses of Atomic Energy, Gemevae, 1955, T, 407 (1956). 3. W. J. James and M.E. Straumanis, Acta. Cryst. 9, 376 (1956). ¥, J. J. Katz and G. T. Seaborg, pp 33-34, "The Chemlstry of the Actinide Ele- ments", McGraw Hill Book Co., New York, 1957. hga., F. W. Schuler, F, L. Steahly and R.W . tan, Paper 7.l in Collected papers, Production and Beparation of Uz , edited by L.I. Katzin, Atomlec Energy Commlsslon Document TID-5223, 1952; avelileble from Office of Techni- cal Services, Dept. of Commerce, Washington 25, D. C. Prlce #3.25. 5. O. Hahn, "Applied Radiochemistry" p3%, Cormell Universlty Press, Ithaca, New York, 1936. ' %. J. W. Hamaker and C. W. Koch, Paper 7.2 and 7.3 in Atomic Energy Commission report TID-5223 (reference La). 6. J. J. Katz and G. T. Seaborg, ref. clted in General Reference Section I. T. C. K. McLane and 8. Peterson, Paper 19.3 in "The Transuranium Elements" ed- i1ted by G. T. Seaborg and J.J. Katz, McGraw Hill Book Co., New York, 1949, 8. F. Hagemann, L.I. Katzin, M. H. Studier, G. T. Seaborg and A. Ghiorso, Phys. Rev. 79, 435 (19505. g, N. E. Ballou in Plutonium Project Report, CC-920, Sept. 15, 1943. 10. L. Gordon and K. J. Shaver, Atomlic Energy Commission Report, NYO 3555, 104 p, Oct. (1952). 11. J.8. Fritz end J.J. Ford, Iowa State College Report ISC-304 (1953). 12. H.H. Willard, A. W. Mosen, R. D. Gardner, Los Alemos Sclentific Laboratory 13. K.A.Krens and R. W. Holmberg, J. Phys. Chem. 58, 325, (1954); see also K.A. Kraus Hydrolytic Behavior of the Heavy Elements, Paper P/731 Proceedings of the Internationsal Conference on the Peaceful Uses of Atomlc Energy, Geneva, 1955, 7, 245 (1956). 4. L.G. 8111€n, Acta. Chem. Scand. 8, 299, 318 (1954). 15. L.G. 8111én, "Polynuclear Complexes Formed in the Hydrolyeis of Metal Ions”, P T4, Proceedings of Symposium on Coordination Chemistry, Corenhagen, Ag, 1953. 67 16. G. Urbaln, Bull. Soc. Chim. France {3]15, 347, (1896). 17. J. Rydberg, Acta Chem. Scand. ), 1503-1522 (1950); Arkiv Keml 5, 517 {1953); Arkiv Kemi 8, 113 (1955). 18. H. Gotte, Z. Naturforsch, 3b, 149-50 (1948). 19. W. Forsling, Acta Chem. Scand. 3, 1133-6 (19493). 20. L. Sacconi and R. Ercoli, Gazz. Chim. ital. 79, 731-8, (1949). 21. D. Dyrssen, Svensk. Kem . Tid, 68, 212, (1953). 22, B. H8k-Bernstrém, Acts Chem. Scand, 10, 174-85, (1956). - 22a. G. Cowan,. Manhattan Project Report, CC-2771l. 23. T. Moeller and M. V. Ramanish, J. Am, Chem. Soc. 76, 2022-4, (1954). 23a. 23b. C. V. Banks and C., H. Boyd, Anal. Chem. 25, 416, (1953). P. F. Thomason, M.A. Perry, W. M. Byerly, Anal. Chem. 21, 1239, (1949). 24, F. Hagemann, J. Amer. Chem. Soc. 72, T68, (1950). es. 26. 27, 27a. 27b. 28. 29. 29a. 30, 31. 32, 33.- 3L, 35, See R. N. Osborne in Radiochemical Procedures in Use at the University of California Radiation Laboratory (Livermore), Report UCRL-4377, (195k), See also Procedures 5 and 6 in Sectlon V below, ¥. H. Spedding, A.Kant, J.M. Wright, J. C. HEET}U£3§. Powell and A.B. New- ton, Peper 8.7 in "Production and Separation of - Collected Papers" edited by L.I. Katzin, Document TID-5223, 1952, availleble from Office of Technical Services, Dept. of Commerce, Washington 25, D. C. g3.25; See also Psper 8.6 in pame volume, J. Rydberg and B. Bernetrfm, Acta.Chem. Scandanevica, 11, 86 (1957). ¥. R. Bruce, Paper P/‘719 in Volume 7, Proceedings of the Internmational Conference on the Peaceful Uses of Atomic Energy, Geneva 1955, United Nations, New York, 1956. Musser, D, P. Kreuse mnd R. H., Smellie, Jr., Report B-4, 380,223).July 19kT7. D. F. Peppard end Co-workers, J. Amer. Chem. Soc., 75, 4576, (1953). H. Levine and F, 5. Grimaldi, Report AECD-3186, Feb. 1950; See also collect- ed Papers on Methods of Analyeis for Thorlum and Uranium, Geologlcal Survey Bulletin, 1006, 1954%. U.S. Gov't Printing Office, Price $1. M.W. Lerner and G.J. Petretic, "Separation of Rare Earths from Thorium Nitrate", New Brunswick Laboretory Report, NBL-108. August 1955. D. M. Hiller and D. S. Marten Jr., "Radiochemical Studies on the Photofission ot Thorium, "Phys. Rev. 90, 581, (1953). J. Marechal-Cornil and E. Picciotto, "'Separation of Natural Radioelements by Mesetyl Oxlde", Bull. Soc. Chim., Belges, 62, 372-82, (1953). Procese Chemistry, Vol 1, edited by F. R. Bruce, J. M, Fletcher, H., H. and J. J. Katz in Progrese in Nuclear Energy; Pergamon Press, London, 1956. Proceedings of the Internmational Conference on the Peaceful Uses of Atomic Energy, Geneva, 1955, Vols 7 and 9, United Natioms, New York, 1956. Proceedings of the 2nd Internationel Conference on the Peaceful Usea of Atomic Energy, Geneva, 1958, United Nations, New York 1959. K. um. F. C, Mo:'d’ W. B. Hardvick and H.A.G. How. J. Inorgmc and Buclear Chem. 4, 100, 1957. ' 36. 3. 38. 39- 40. 41. h2. 43. L, 45, 46, ,"71 148. D. Soargill, K. Alcock, J. M. Fletcher, E. Besford, and H.A.C. McEay, ~J. Inorg. MNucl. Chem, 4, 304, 1957 G. F. Best, H.A.C. McKay and F. R, Woodgate, J. Inorg. Nual. Ghem. 4, 315, 1957. E. Heaford, H.A.C. McKay and D. Scargill, J. Inorg. and Nucl. Chem. &, 321, 1957, Studies of the Solvent Extrection Behavlior of the Trlvalent Rare Earths, D. ¥. Peppard, J. P. Fari, P. R. Gray and G. W. Mason, J. Phys. Chem. 57, 294, (1953). Extraction of Lanthanides in tributyl phosphate - nitrlc acld extraction Systems, D. F. Peppard, W. J. Driscoll, R. J. Sironen and S. McCarty, J. Inorg. and Nucl. Chem. k, 326, (1957) The Distribution of Some Actinides and Fission Products between Tributyl Phosphate and Aqueous Solutions of HNO_ and Ca(NOz3)., B. Bernstrém and J. Rydberg, Acta Chemica Scandinevica il 1173 (135% Interrelationships 1n the Solvent Extraction Behavior of Scandium, Thorium and Zirconlum in Certain Tributyl Phosphate - Mineral Acid Systems, D. F. Peppard, G. W. Mason and J. L. Maler, J. Inorg. and Nucl. Chem. 3, 215 (1956) : The Mutual Separation of Thorium Protactinium and Uranium by Tributyl Phos- phate Extraction from Hydrochloric Aecid, D. ¥. Peppard, G. W. Mason and andi M. V. Gergel, J. Inorg. and Nucl. Chem. 3, 370 (1957) Solvent Extractlon Chemlistry of the Pission Products, Paper P/719 by F.R. Bruce in Vol. 7, Proceedings of the Internationsl Conference on the Peace- ful Uses of Atomic Bnergy, Geneva 1955, United Nations, New York, 1956. "Fractional Extraction of the Lenthanides as their Di-alkyl Orthophosphates”, D.F. Peppard, G. W. Mason, J.L. Arer and W. J. Driscoll, J.Inorg. Nucl. Chem. 4, 334, 1957 "Acidic Reters of Orthophosphoric Acld as 8elective Extrsctants for Metallic Cations - Tracer Studies", D. F. Peppard, G. W. Mason, W. J. Driscoll and R. J. Sironen, J. Inorg. Nucl. Chem. 7, 276 (1958). "Isolation of Berkelium by Solvent Extraction of the Tetravalent Species 3 D.F. Peppard, 3. W. Moline and G. W. Mason, J. Inorg. Nuclear Chem. L, 34k, (1957.) "The Use of Tri-n-octylphosphine Oxide in the Solvent Extraction of Thorium from Acidic Solutions”, W. J, Ross and J. C. W]:L‘Lte, Oek Ridge National Lab- oratory Report, ORNL 2627. 49. R. M, Diemond, K. Street Jr., and G. T. Seaborg, J. Am. Chem. Soc. 76, 1461, (1954). 50. R. W. Bane, Report CC-3336, Nov. 23, 1945. 51. D. Dryssen, Svensk. Kem. Tid, 62, 153 (1950). 52, F. Asaro, F. Stephens Jr., and I. Perlman, Phys. Rev. 92, 1495 (1953). 3. 54. K. A. Kraus, G. E. Moore, and F., Neleon, J. Amer. Chem. Soc. 78, 2692 (1956); ibid 72, 4283 (1950); 73, 2900 (1951); T7, 1383 (1955). K. A. Kraus and F. Nelson, Paper P/837 in Vol. 7 of Proceedings of the Inter- national Conference on the Peaceful Uses of Atomlc Energy, Geneva, 1955, United Natlons, New York, 1956; Single copies of thls paper may still be avallable for A 25 from United Nstioms Bdbkstore, New York, S5ha, R.H, Poirier and A.E. Bearse, Battelle Memorial Institute Report, BMI-242 55. hugust 1950, T1 p. J. Danon, J. Amer, Chem. Soc. 78, 5953 (1956). 69 56. 27. 58. 29. D. J. Carswell, J. Inorg. Nucl. Chem. 3, 384, 1957. L. R. Bunney, N. E. Ballou, J. Pascual and 8. Fotl, "Anlon-Exchange Behavior of Several Metal Ions in HCl, HNO. and EZSO% Solutions with Dowex-2", U.8. ’ val ologleal Defenge Laborad R USNRDL-TR-228, May 12, 1958. e e oR ok £a DSt m R R PSS VSBY , PT88S: ) Moy 12, 195 E. C. Freiling, J. Pascual and A. A. Delucchi, "Anion Exchange Studles in Phosphoric Acid Solutions", USNRDL-TR-231, May 7, 1958. Also publighed in Anal. Chem. 31, 330, 1959. _ , J. Danon, J. Inorg. Nuclear Chem. 5, 237 (1958). Ballou, K. E., Hume, D. N., Nationel Kuclear Energy Series, Div. IV, Vol. 9, 1755-7, McGraw-Hill, New York, 1951. Hagemenn, F., J.iAm.IChem. Soc. 72, 768 (1950). Koshlend, D. E., Jr.,.Oak_Ridge Hational-Laboratory Unclassified Report, CN-2041 (Jen. 8, 1945). Potratz, H. A., Los_Alamog UhélaSsified RePOrt, LA-1T21 (Sapt.lo, 1954%). See Procedure 9 above. Rickerd, R. R., Osk Ridge Natlionel Laboratory, Oak Ridge, Tenn., private commmication. Printad In the United States of Amarica USDOE Technlcal Information Center, Ook Ridge, Tannsuss TO NUCLEAR SCIENCE SERIES: MONOGRAPHS ON RADIOCHEMISTRY AND RADIOCHEMICAL TECHNIQUES Available from the National Technical Information Service, U. S. Department of Commerce, Springfield, Virginia 22161 ELEMENTS Aluminum and Gallium, NAS-NS-3032 [1961], $9.25 Americium and Curium, NAS-NS-3006 [1960], $9.75 : Antimony, NAS-NS-3033 [1961], $9.50 Arsenic, NAS-NS-3002 (Rev.) [1965], $9.00 Astatine, NAS-NS-3012 [1960], $8.75 Barium, Calcium, and Strontium, NAS-NS- 3010 [1960]. $11.00 Beryllium, NAS-NS-3013 [1960], $9.50 ‘Bismuth, NAS-NS-3061 [1977], $11.75 Cadmium, NAS-NS-3001 [1960], $9.50 Carbon, Nitrogen, and Oxygen, NAS-NS- 3019 [1960), $8.50 Cesium, NAS-NS-3036 [1961], $9.75 Chromium, NAS-NS-3007 {Rev.) [1963], $9.50 Cobalt, NAS-NS-3041 [1961], $10.25 Copper, NAS-NS-3027 [1981], $9.60 Fluorine, Chlorine, Bromine, and ledine, NAS-NS-3005 [1960], $9.25 Francium, NAS-NS-3003 [1960], $9.00 Germanium, NAS-NS-3043 [1961], $9.25 Gold, NAS-NS-3036 [1961], $9.00 Indium, NAS-NS-3014 [1960], $9.50 lodine, NAS-NS-3062 [1977], $11.00 Iridium, NAS-NS-3045 [1961], $8.75 Iron, NAS-NS-3017 [1960], $11.75 Lead, NAS-NS-3040 [1961], $12.00 Magnesium, NAS-NS-3024 [1961], $8.76 Manganese, NAS-NS-3018 (Rev.) [1971], $9.75 Mercury, NAS-NS-3026 (Rev.) [1970Q], $13.00 Molybdenum, NAS-NS-3009 [1960], $9.00 Neptunium, NAS-NS-3060 [1974], $13.75 Nickel, NAS-NS-3051 [1961], $11.25 Niobium and Tantalum, NAS-NS-3039 [1961], $9.50 ' Osmium, NAS-NS-3046 [1961]. $8.50 Palladium, NAS-NS-3052 [1961], $11.00 Phasphorus, NAS-NS-3056 [1962], $9.00 Platinum, NAS-NS-3044 [1961], $8.75 Plutonium, NAS-NS-3058 [1966], $12.75 Polonium, NAS-NS-3037 [1961), $9.76 Potassium, NAS-NS-3048 [1961], $9.26 Protactinium, NAS-NS-3016 [1959], $10.00 Radium, NAS-NS-3057 [1964], $13.26 Rare Eerths—Scandium, Yttrium, and Actinium, NAS-NS-3020 [1961], $16.00 Rare Gases, NAS-N5-3025 [1960], $9.50 Recent Radiochemical Separation Procedures for As, At, Be, Mg, Ni, Ru, and Se, NAS-NS- 3059 [1974], $10.25 Rhenium, NAS-NS-3028 [1961], $9.26 Rhodium, NAS-NS-3008 (Rev.) [1965]. $10.00 Aubidium, NAS-NS-3053 [1962], $10.25 Ruthenium, NAS-NS-3029 [1961], $10.00 Selenium, NAS-NS-3030 {Rev.) [1965], $9.50 Silicon, NAS-NS-3049 (Rev.) [1968], $10.00 Silver, NAS-NS-3047 [1961], $9.50 Sodium, NAS-NS-3055 [1962], $9.25 Sulfur, NAS-NS-3054 [1961], $9.50 Technetium, NAS-NS-3021 [1960], $9.50 Tellurium, NAS-NS-3038 [1960], $9.25 Thorium, NAS-NS-3004 [1960], $9.75 . Tin, NAS-NS-3023 [1960], $9.75 Titanium, NAS-NS-3034 (Rev.) [1971]. $10.26 Transcurium Elements, NAS-NS-3031 [1960), $9.00 . Tungsten, NAS-NS-3042 [1961], $9.25 Uranium, NAS-NS-3050 [1961], $17.00 Vanadium, NAS-NS-3022 [1960], $10.00 Zinc, NAS-NS-3015 [1980], $9.50 Zirconium and Hafnium, NAS-NS-3011 [1960], $9.50 TECHNIQUES Absolute Maasurement of Alpha Emission and Spontaneous Fission, NAS-NS-3112 [1968], $9.75 Activation Analysis with Charged Particles, ' NAS-NS-3110 [1966], $9.25 Application of Distillation Techniques to Radiochemical Separations, NAS-NS-3108 [1962],-$8.00 Applications of Computers to Nuclear and Radiochemistry, NAS-NS-3107 [1962], $16.00 Cation-Exchange Techniques in Radio- chemistry, NAS-NS-3113 [1971], $13.00 Chemical Yield Determinations in Redio- chemistry, NAS-NS-3111 [1967], $10.50 Detection and Measurement of Nuclear Radiation, NAS-NS-3105 [1961], $11.50 Liquid-Liquid Extraction with High- Molecular-Weight Amines, NAS-NS5-3101 [1960], $10.25 Low-Level Rediochemical Separations, NAS-NS-3103 [1981], $9.00 Neutron Activation Techniques for the Measlre- ment of Trace Metals in Environmental Samples, NAS-NS-3114 [1974], $10.26 Paper Chromatogrephic and Electromigration Techniques in Radiochemistry, NAS-NS- 3106 [1962], $9.25 Processing of Counting Data, NAS-NS-3108 [1966], $12.25 Rapid Radiochemical Separations, NAS-NS- 3104 [1861], $11.26 : Seperations by Solvant Extraction with Tri-n-octylphosphine Oxide, NAS-NS-3102 [1961]}, $9.50 _ Users” Guides for Radioactivity Standards, NAS-NS-3115 [1974], $10.26 Current as of January 1982