. -..'. . . . . . I OFT ORNLP 1381 . ! T ET PA . M i. .. . il ,!.. f i... . AO .. is . . MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS - 1963 . URNU-P-1384 KASI! PRICES U 18 RET:3:0 FOR ANNOUNCEMENT IN NUCLEAR SCIENCE ABSTRACTS May 26, 1965 H.C. $ 1.00, MN. 50 Material for Submission to R. I. Strough of Pratt and Whitney for, Inclusion in an AIAA Paper Summarizing the "State--the-Art for litla poes Nuclear Electric Space Power Plants* e-Art for } in que A. P. Fraas Oak Ridge Nat: inal Laboratory Oak Ridge, Tennessee The MFRE is a 1-Mw (thermal) output, single-fluid, potassium-vapor DALRankine cycle system designed for construction of stainless steel and intended to cperate with a reactor outlet temperature of 1500 to 1600°F. in the -NOT_EOR RUBLIC RELEASE..DEEICUL Potassium serves as the reactor coolant, the working fluid of the thermo- A Die Nuwen dynamic cycle, the lubricant for the bearings, and the coolant for the PROCEDURSSON father urid generator. The system is under development as a project of the Advanced Reactor Technology Branch of the Division of Reactor Development and Technology of the AEC. A reference design of a launch package, 10 ft in diameter and 15 ft high, has been prepared and is shown in Fig. 1. To facilitate shakedown and maintenance, this design has been modified for the reactor experiment by moving the reactor downward and to one side of the radiator so that it can be enclosed in a heavy concrete shield, and similarly moving the turbine generator, feed pump, and feed-heater complex downward and toward the other side to facilitate inspection, repair or re- placement of units. This arrangement is shown in Fig. 2. The present program does not include funds for the development of a turbine generator; it is hoped that a suitable unit will become available from the SNAP-50 Program. Pending the availability of such a unit, it is planned to use an orifice coupled with some heat transfer surfaces to simulate the turbine generator. The over-all thermal efficiency of the system will depend on the ef- ficiency of the turbine and the generator. If a unit designed expressly *Research sponsored by the U. S. Atomic Energy Commission under contract with the Union Carbide Corporation. - - - - - - for the MPRE were used, it would probably be possible to obtain an over- all thermal efficiency approaching 15%. On the other hand, if a unit designed for the SNAP 50 Program were employed, modifying it to fit into the MPRE system may compromise the performance substantially so that the over-all thermal efficiency might be only 10%. The life of a power plant of this sort may be limited by loss of reactivity stemming from ournup, deterioration of the fuel elements as a consequence of irradiation, corrosion or mass transfer in the system, bearing wear or deterioration, distortion of components in the system, or leaks that may develop as a consequence of thermal cycling or other factors. The MPRE has been designed so that there is no obvious limi- tation imposed by any one of these for a design life of 10,000 hr. While the MPRE component test program has not progressed sufficiently to provide a basis for predicting the life of components, ORNL experience on the ANP and Molten Salt Reactor Programs is encouraging in this respect, e.g., five pumps having outputs of 500 to 1500 gpm were operated for periods in excess of 20,000 hr at temperatures above 1200°F with no difficulty in the pumps themselves, although there were quite a number of forced shutdowns caused by difficulty with the electrical switch gear and drive motors.2 The cost data available are not sufficient to make a good estimate of the cost of production quantities of launch packages of the MPRE type; however, the MPRE Program is proving to be much less expensive than the programs for other nuclear-electric space power plant systems. It is bea lieved that one of the major reasons for this is the relative simplicity of the system, with its small number of components made of conventional materials, and it appears likely that these same factors will make the cost of the power plant in production quantities much less than that for any other system of comparable power output. It should be pointed out that there is no basic reason why a boiling potassium reactor system of this type could not be designed for either a smaller or a much larger power output than the 1 mw (thermal) projected for the MPRE. The major problems in the MPRE Program are those associated with reactor control, flow stability in the boiler and condenser, component matching to minimize control functions, and component reliability. An orderly series of experiments was laid out four years ago (six months after the MPRE Program was initiated) to investigate these problems in a logical, progressive sequence. With one exception, the major com- ponent tests chosen from this program have been built and are now operating; the last one is under construction. Construction of the MPRE power plant itself will begin when tests with these systems show that all of the problems are well in hand. We expect to reach this point next year, and we hope to be ready to begin operation of the MPRE in 1968. These dates ere, of course, con- tingent on the experimental test experience. This, in turn, will depend on both the soundness of the design and a certain amount of luck. The boiling potassium reactor system was chosen for development be- cause it gave promise of yielding a lighter, more compact, simpler, and more reliable power plant than any other that has been given serious consideration. By carrying out the boiling process in the reactcr itself, not oniy is it possible to eliminate the weight and complexity of a separate boiler and an additional fluid circuit with its associated LEGAL NOTICE This report me proparod u an account of Government sponsored work, Nellber Ibo Valled Stalas, por la Commission, nor any person er ung on beball of the Commissioni A. Mukes any warranty or reprowatauon, expressed or implied, wild respect to the accu- racy, completeness, or usefalpose of the Laformation conualdad la the report, or that the we of any information, apparatus, molhod, or process disclosed in Wlo report may not lalringo prinatoly owad richua; or B. AsNmus any llabillues with respect to use of, or for damage resujung from the um of any information, apparta, matbod, or procesu diocloud In Wado roport. As und la the above, "persoa acting on baball of the Communion" includes any on- ployee or coalnactor of the Commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor proparus, dienniaatas, or provides access to, mny Information pursuant to dio employmat or contract will the Commissiva, or ho employment with such contractor, ------- piping, pump and drive motor, the expansion tank, the fluid in that circuit, and much instrumentation and control equipment, but it is also possible to increase the turbine inlet temperature by approxi- mately 200°F for a given permissible fuel element temperature. In the system under development it appears possible to elimi: ate many of the control functions of a two-fluid system, and this should further increase the reliability since test experience indicates that the in- cidence of forced outages caused by faults in the instrumentation and control equipment is likely to be higher than the incidence of forced outages caused by faults in the mechani.cal elements of the system. While the MPRE has been designed to operate under zero-gravity conditions, and a number of tests or MPRE components have been made with encouraging results both in the NASA Lewis Lab Drop Tower and in the Air Force KC-135 at Wright Field, there can be no assurance that a complete system will operate under zero-gravity conditions until one has actually operated in orbit. We are confident that a sinall centri- fugal field would suffice to stabilize the free-liquid surfaces for a manned space vehicle designed to whirl, and the 1/6-g gravitational field of the moon would certainly assure satisfactory conditions for a lunar base power plant. For unmanned and other vehicles in which whirling is to be avoided, there is reason to believe that it will be possible to achieve satisfactory control of the free-liquid surfaces under pure zero-gravity conditions, although it probably will ve necessary either to maintain a small acceleration of the vehicle during startup of the power plant or to launch the power plant with fluid circu- lation maintained by the addition of heat from chemical fuel. var NOSE COWE S t ations minimum vins e t des .. memberi makan RADIATOR FOR GENERATOR COOLING SYSTEM 1 13 ore WINDSHIE:0 - 110 FT PA. IMG FT MIGHT by madintre toa... e VAPOR MANIFOLD 1 - - mango homens passarinhos MAIN TURBINE W W D f .... **** linguri GENERATOR inimuosimamalimos miserima immediatamengonome AAS REGENERATOR (GEMERATOR COOLING SYSTEN) - CONICAL REFLECTOR FOR SHIELO CONDENSATE RE TURN LINE -FINNED TAPERED RADIATOR TUBES Hie milioni m INVOLUTE REFLECTOR ...we FEED PUMP -- REACTOR AND SHIELO ASSEMBLY -CONDENSATE MANIFOLO R-108-61 Fig. 1. Reference Design for a Launch Package ܘܢܫܚܶܢܪܝܢܚܟܗܝܪܝܺܫܳܚܕ݁ܝܽܐܕ݂ܡܵܫܵܐ 85 ܂ ܂ ܙ -… ܙܫܢ ܙ •• •• »: . . ' . ' . . . ܂ • • • • •• …… . .. ܚܫܫܙ ;.. ܐ ܥܒܫܚ.... .ܐ References 1.. A. P. Fraas, "The MPRE - A Boiling Potassium Reactor System," presented at the AIAA Third Biennial Aerospace Power Systems Conference, September 1-4, 1964, :In Philadelphia, Pa. AIAA Paper No. 64-763. 2. A. P. Fraas, "Reliability as a Criterion in Nuclear Space Power Plant Design, " presented at the 1964 SAE-ASME National Aeronautics and Space Meeting in New York, April 27-30, 1961t. Paper No. 861A. tatiminen :--Trini END f - . DATE FILMED 6 / 27 /66