| ORNT, Pl R T e . OAK RIDGE |q‘\7[§i"“tJefiijfiggfifiavnfi3152}5?3‘E’ operated by UNION CARBIDE CORPORATION for the ' U.S. ATOMIC ENERGY COMMISSION ORNL- TM- 268 COPY NO. - 4 DATE - July 5, 1962 EXPERIMENTAL 5 Mw THERMAL CONVECTION MOLTEN SALT REACTOR J. Zasler Abstract A preliminary study has been made of an experimental 5 Mw thermal convection molten salt reactor. This reactor can be converted, after a veriod of low power operation, to a 50 Mw pilot power plant by adding a fuel pump, a larger sodium pump, and a turbo generator with associated equip- ment. NOTICE This document contains information of a preliminary nature and was prepored primarily for internal use ot the Oak Ridge National Laboratory., It is subject to revision or correction and therefore does not represent g final report. The information is not to be abstracted, reprinted or otherwise given public dis- semination without the approval of the ORNL patent branch, Legal and Infor- mation Cantrol Department, Introduction Based on the history of other reactor types, the development and demon- stration of the molten salt power reactor concept will reguire the operation of a small axperimfintal reactor and a medium sized pilot plant. The simplest and most reliable experimental reactor system appears to be a thermal convec- tion reactor. The chief dlsadvantages of the natural convection system - in- creased fuel volume and larger heat exchangerb are not major factors in a five Mw reactcr. By adding a fuel pump to the 5 Mw reactor, it is possible to increase the capacity of the fuel system from 5 to 50 Mw. This, of course, must be accom- panied by a corresponding increase in the capacity of the heat dump. It is thus possible to build one reactor that will serve. successively as a small ex- perimental reactor and a pilot plent. fieséription of Reactor Fig. l shows an elevation of the reactor plant; Fig. 2 is a plan view The dimensions and operating conditions for 5 and 50 Mw operation are given in Table I. The reactor is five feet in diameter with a 6 inch thick blanket surrounding the core {see Appendix A). Prcvisions are made to connect the blanket and fuel regions so that the reactor can be operated as a one reglon reactor. The 5 Mw reactor is inherently simple anéxrellable aflfi requlres no develop- ment of componerts. No fuel or blenket pumps are required. The sodium pump is -~ a standard PK pump- : ’ In order to provide for future 50 Mw operation of the system, it is necessary that the fuel expansion tank be so designed that'a sump type fuel pump can be installed in it and the sodium lines leading to the heat exchanger be sized to " handle the flow required for 50 Mw operation. The 5 Mw reactor, would serve the following purposes: 1. Demonstrate the continuing operation of a molten salt reactor. 2. Provide in-pile corrosicn data. (Thls could be done by inserting removable - samples in both the het and cold legs.) 5. Develop and demonstrate remote,malntengnce(grocedureso L. By replacing the air heat dump with a steam heat dump it could be used to demonstrate sodium to steam heat transfer. ‘ Conversicon to 50 Mw operation Waen the above has been accomplished, the system can be converted to 50 Mw coperation and operated as a pilot power plant. Although this plant would not be identical to the reference design plant, there would be enough points of similarity, especially in contrcl, cerrosion, and maintenance problems so that successful operation would lead directly to the design and comnstruction of a large power plant. Conversion to 50 Mw Operation {continued) The only modification required to the fuel circuit is the installation of & sump type fuel pump in the fuel expansion tank. The fuel to sodium heat exchanger designed for the 5 Mw operation would be satisfactory for 50 Mw operation, because of the reduction in the fuel film resistance in going from laminar flow at the lower power to turbulent flow at the higher power. A complete analysis of the blanket circuit has not been made, however, rough caléulations show the pessibility of &851gning a thermal convection blanket circuit that could be used at both power levels. If this turns out to be impracticsel, a blanket pump can be installed for. 50 Mw operation. The sodium systém is cut at the points shown in Figs. 1 an& 2 and a new system consisting of a 10,000 gpm pump and sodium to steam heat exchanger is installed. A turbo-~generator and asscaaafied equipment is also installed to ccmplete the pilet plant. Cost Estimate Table II shows & rough cost estimate, of approxrmafiely $10 000, 1000 for the constrtuction of the 5 Mw plant. ‘For approximately $10 000, 000 addltzonal, this plant could be converted to the 50 Mw - 51ze, as shown in Table 1I1. No attempt was made in thls llmited study to optimize ezther the 5 or 50 Mw plants. Further study would undoubtedly be profitable. The 5 ané 5Q. Mw pover levels wer= chosen arbitrarily and it is quite possible that a differént choice is preferable. A number of problems remain which were not investigated but which appear to be cgpable of solution. Among these are: 1) the design of the blanket c1rcu1t, 2) the method of removing fission gas, 3) the design of the 5 Mw heat dump, and 4) the design of the steam system. 7 Acknowledgements Acknowledgement ‘iz made to L. G. Alexander for sélecting the Uranium con~- centration and core size and to G. D. Whitman and M. E, Lackey for consultation on the cost estimate and heat transfer, respectively. Table I Power Output Mw {thermal}. 5,19 50 Mw Reactor Core Size ft Blanket Thickness £t | 1/2 Power Density watts/cc 1.5 15 Fuel Pump none Sump type Riser and Downcomer Dia. in 10" Height of Fuel Heat Exchanger {above reactor centerline) £t 20 Fuel Velocity in Riser ft/sec .64 6.17 Fuel Head ft . 39 12.66 Fuel Volume £t5 " 120 Fuel Flow gal/min- 158 1515 Sodium Flow gal/min 578 9250 Sodium Pump PK Heat Exchanger Tube I.D. in .6 Tube Wall Thickness in 050 Tube Length ' ft 20 No. of Tubes 250 Shell C. Dia. in 18 Shell Wall Thickness in . 375 Fuel Temp. in OF 1210 1210 Fuel Temp. out Op 1010 1010 Na Temp. in : op 850 850 Na Temp. out OF 1100 10C0 D. Table 1T Cost Estimate ~ 5 Mw Experimentsal Reactor Engineering, Design and Inspection Construction Costs - 1. Land and Land Rights 2. Improvement and Land 3. Buildings ~ Reactor Plant and Auxiliary Reactor Structure (containment and shielding) Instruments and Control Reactor System Fuel Blanket Bodium Maintenance Auxiliaries Inventories Building Sub~Total Heat Removal Contingency st 10% Total $ 800,000 500,000 480,000 480,000 60,000 162,000 500,000 200,000 416,000 2,000,000 g 3,000,000 750,000 5,118,000 500,000 1,000,000 g10, 368,000 2 & & ° e 2 ey . A e “ v m a e a w .,y W A R NP NI I e 7 NN UNCILASSIFIED PHOTO 31646 FUEL TO SODIUM HEAT EXCHANGER TURBO-GENERATOR ROOM {for future expansion) 0 5 0 {1y ;Et]gf;ia [ihde] SCALE-FEET 84 143 FT. FIG.O PLAN VIEW OF 5MW EXPERIMENTAL MOLTEN SALT REACTOR PLANT FT. _0‘[_. -&" 1-3. b, wld- Distribution DTIE, AEC M. J. Skinner