A Transient Simulation Test Rig for Heat Pipe Cooled Space Nuclear Reactors

1. A Transient Simulation Test Rig for Heat Pipe Cooled Space Nuclear Reactors Adam Wheeler, Andrew Klein Department of Nuclear Engineering & Radiation Health Physics Oregon State University February 25, 2013

2. Outline • Introduction • Reference design • Variations from the Reference Design • Modeling programs • SolidWorks • STELLA • Models • Goals • Assumptions • Results from analysis • Discussion of results • Conclusion and future work • References

3. Introduction • Objective: Develop and analyze a test facility based on a 1 to 10kWe heat-pipe cooled space nuclear reactor • Goals: • Design a feasible test facility • Predict steady state performance • Predict transient responses • Method: Use a lumped parameter model and a 3D CAD simulation program for analysis

4. Reference Design • Reference system is a 1 to 10kWe reactor module • Developed by a collaboration between NASA Glenn and Marshall Research Centers and Los Alamos National Laboratory

5. Variations from the Reference Design Original Design • 1000K sodium heat pipes in core • 8 to 16 heat pipes from core to power convertors • Pin or plate fuel interface to heat pipes • Direct energy conversion via Stirling engines or Thermoelectrics • Cone-shaped radiator array Test Facility • 600K water heat pipes in core simulator • 8 heat pipes between core & power convertor simulators • Stainless steel cylinder interface to heat pipes • Power conversion thermal absorption simulator • Cylindrical radiator array

6. Modeling Programs SolidWorks • Used for 3D rendering and various types of simulations • Flow Simulation package allows for heat and fluid flow in a time dependent simulation • Lacks computational stability and speed but can give very detailed results STELLA • Object oriented flow based system • Great for modeling the transfer of some item (heat, chemicals, water, population, etc.) to another location through time • Lacks accuracy and detail but is very versatile and fast (STELLA can be made more accurate but quickly reaches a diminishing return in effort and time which makes more complex CFD programs more attractive)

7. Limits to the System • Upper bounds: • 700K in the heat pipes from the core to the ECS • 550K in the radiator array heat pipes • 1600K in the stainless steel cylinders • Lower bounds: • 600K in the heat pipes from the core to the ECS • 450K in the radiator array heat pipes

8. SolidWorksModel Boundary Conditions • To simulate the affects of convection, a direct heat sink boundary condition was applied which simplified the model • A heat source was placed in the core simulator’s heater rods • To model the heat pipes, a custom material with very high conductance at the heat pipe’s operating temperatures was used along with the heat pipe operator in Flow Simulation • Radiation transfer boundary conditions were placed on the outer surfaces of the model ECS

9. Stella Model Assumptions • Axial heat transfer is negligible in comparison to radial heat transfer • Heat transfer to and from sinks and sources can be done with 1D radial methods • Adiabatic boundary conditions assumed for outer edges of the system

10. Stella Model Energy Conversion Simulator Cross-section Core Simulator Cross-section

11. STELLA Model • STELLA model uses three basic components • Convertor • Used to control flow and system variables • Reservoir • Points for collecting the heat passing through system • Bidirectional flow • Forces directional flow between Reservoirs and • Controlled by connections between Convertors and Reservoirs

12. STELLA Model

13. STELLA Model • The whole thing:

14. STELLA Results: Startup

15. SolidWorksResults: Startup

16. SolidWorksResults: Startup

17. STELLA Results: One HP Lost

18. STELLA Results: One HP Lost Increasing Time

19. SolidWorksResults: One HP Lost

20. SolidWorksResults: One HP Lost

21. STELLA Results: Two Consecutive HPs Lost

22. STELLA Results: Two Consecutive HPs Lost

23. SolidWorksResults: Two Consecutive HPs Lost

24. SolidWorksResults: Two Consecutive HPs Lost

25. STELLA Results: Three Consecutive HPs Lost

26. STELLA Results: Three Consecutive HPs Lost

27. SolidWorksResults: Three Consecutive HPs Lost

28. SolidWorksResults: Three Consecutive HPs Lost

29. STELLA Results: Opposite HPs Lost

30. SolidWorksResults: Opposite HPs Lost

31. SolidWorksResults: Opposite HPs Lost

32. Discussion of Results • STELLA results: • System is fast in responding to heat transients • Temperature changes as a result of heat pipe losses are less then 100K • SolidWorksresults: • Reasonably agree with the STELLA time and temperature results, and show in greater detail the temperature differences across the system

33. Conclusion and Future Work • The computational models gave a decent result that can be used for future analysis • Future work: • Increasing accuracy in STELLA model • Exact design specifications • Cost of actually building the facility • Gravity scaling • Finding a functional variable heat absorption method

34. References Polzin, K. A., & Godfrey, T. J., “Flow Components in a NaK Test Loop Designed to Simulate Conditions on a Nuclear Surface Power Reactor.” AIP Conference Proceedings. Sanzi, J. L., “Thermal Performances of High Temperature Titanium - Water Heat Pipes by Multiple Heat Pipe Manufacturers.” AIP Conference Proceedings. (2007). Sarraf, D. B., & Anderson, W. G., “Heat Pipes for High Temperature Thermal Managment.” IPACK2007. (2007). Poston, D., Kapernick, R., Dixon, D., Reid, R., Mason, L., “Reactor Module Design for a Kilowatt-Class Space Reactor Power System.” NETS 2012 Conference Proceedings. (2012). El-Genk, M. S., Tounier, J., “High Temperature Water Heat Pipes Radiator for a Brayton Space Reactor Power System.” AIP Conference Proceedings. (2006) Bergman, T. L., Lavine, A. S., Incropera, F. P., Dewitt, D. P., “Fundamentals of Heat and Mass Transfer” 7th ed. Anderson, W. G., & Tarau, C., “Variable Conductance Heat Pipes for Radioisotope Stirling Systems.” AIP Conference Proceedings. Reay, D., Kew, P., “Heat Pipes.” 5th ed. p107-141. Tarau, C., Anderson, W. G., Miller, W. O., & Ramirez, R., “Sodium VCHP with Carbon-Carbon Radiator for Radioisotope Stirling Systems.” AIP Conference Proceedings. isee Systems, STELLA Systems Thinking for Education and Research. http://www.iseesystems.com/softwares/Education /StellaSoftware.aspx Perez, D. M. , M. A. Lillo, G. S. Chang, G. A. Roth, N. E. Woolstenhulme, D. M. Wachs, “RERTR-10 Irradiation Summary Report.” May 2011. WATLOW, HT FIREROD cylindrical heaters, http://www.watlow.com/index.cfm Hoa, C., Demolder, B., Alexandre, A., “Roadmap for developing heat pipes for ALCATEL SPACE’s satellites.” Applied Thermal Engineering. 23 (2003) 1099- 1108. Mascari, F., Vella, G., Woods, BG., D’Auria, F., “Analyses of the OSU-MASLWR Experimental Test Facility.” Science and Technology of Nuclear Installations. (2151-0032) 2012, p.19. Reyes, J. N. Jr., Hochreiter, L., “Scaling analysis for the OSU AP600 test facility (APEX).” Nuclear Engineering and Design. Volume 186, Issues 1-2, 11/1/1998, p. 53-109. Kauffman, AC., Miller, DW., Radcliff, TD., Maupin, KW., Mills, DJ., Penrod, VM., “High-Temperature Test Facility for Reactor In-Core Sensor Testing.” Nuclear Technology. (0029-5450), 11/2002, Volume 140, Issue 2, pp. 222-232. ASRG, “Space Radioisotope Power Systems.” Advanced Stirling Radioisotope Generator. January 2011. http://www.ne.doe.gov/pdfFiles/factSheets/SpaceRadioisotopePowerSystemsASRG.pdf Questions?