Nuclear Reactor Power Systems

1. Nuclear Reactor Power Systems Dwight L. Williams, Ph.D., P.E. Potomac Chapter Maryland Society of Professional Engineers 27 October 2005

3. Dwight Williams at a Glance Education and Registration: Nuclear Engineering Ph.D. -- University of Maryland B.S., M.S. -- North Carolina State University Licensed Professional Engineer, Commonwealth of Virginia Professional Experience: Department of Defense Awards and Activities 2005 - 2006 Young Engineer of the Year, NSPE 2004 - 2005 Young Engineer of the Year, DCCEAS 2003 - 2004 Young Engineer of the Year, MDSPE

4. Power Systems

5. Nuclear Primer Subatomic Particles Concept of Isotopes Concept of Half-Life Types of Radiation

6. Subatomic Particles

7. Concept of Isotopes

8. Concept of Half-Life

9. Types of Radiation

10. Categories of Nuclear Reactors Light Water Reactors Use H2O Most Prevalent Heavy Water Reactors Use D2O Prevalent in Canada and Russia Other Reactor Categories Liquid Metal Cooled Gas Cooled

11. Light Water Reactors Boiling Water Reactors (BWRs) Located throughout U.S., Europe, and Asia Power: 570 -- 1300 MWe; Efficiency: ~30% Tmax: 570oF; PRxr Coolant: 1000 psi Pressurized Water Reactors (PWRs) Manufactured by U.S., European, and Asian companies Tmax: 590oF; PRxr Coolant: 2250 psi VVER Reactors (VVERs) -- Russian PWR

12. BWR

13. PWR

14. VVER

15. Heavy Water Reactors Canadian Deuterium-Uranium (CANDU) Reactors Use natural (non-isotopically concentrated) uranium Tmax: 590oF; PRxr Coolant: 1500 psi Can run 2 � years without refueling/downtime RBMK Reactors Chernobyl-style reactor Graphite and D2O in reactor core Much improved designs today

16. CANDU Reactor

17. RBMK Reactor

18. Other Reactor Categories Liquid Metal Fast Breeder Reactors (LMFBRs) Use liquid sodium as coolant 3-loop cycle None operating commercially Advanced Gas-cooled Reactors (AGRs) Use natural uranium He or CO2 gas coolant at 1430oF and 600 psi Primarily operated in United Kingdom

19. LMFBR

20. AGR

21. Nuclear Power Gone Awry Three Mile Island (TMI, 1979) -- PWR Problems began at 4 a.m. Reactor coolant flow became blocked Primary emergency systems responded properly Secondary emergency systems responded properly HOWEVER, operator did not believe secondary systems were working properly so he shut them off Result: Partial core meltdown, minute radiation release TMI Lesson: Minimize operator�s ability to impede automated emergency systems

22. Nuclear Power Gone Awry (Cont.) Chernobyl (1986) -- RBMK (no containment vessel) Experiment to take place during scheduled shutdown Primary and secondary emergency systems known to work effectively; even so, ternary emergency system sought and investigated In order to isolate role/effect of ternary system, primary and secondary systems manually shut off HOWEVER, ternary system did not work properly Result: Core meltdown, explosion, major radiation release Chernobyl Lesson: Minimize operator�s ability to impede automated emergency systems

23. Summary Nuclear Power Reactors Serve Same Role as Other Power Cycle Heat Sources Several Types of Nuclear Power Reactors Exist Most Recent Nuclear Accidents were Likely Preventable Operator errors crippled automated systems Another TMI is nearly impossible Another Chernobyl is unlikely

24. For More Information Visit �The Virtual Nuclear Tourist� website at http://www.nucleartourist.com E-mail Dwight Williams at mdyoungengineer@nspe.org

25. Neutron Moderation (Backup) For most nuclear reactors, fission is initiated by slow neutrons (even though the fission neutrons generated are fast) Liquid Metal FAST Breeder Reactor (LMFBR) is one of few reactors that does not initiate fission with SLOW neutrons Goal: Slow down neutrons to make them available for fission, but keep neutrons from being absorbed into a nucleus while slowing them down Best Substances: 1. D2O 2. Carbon 3. H2O

26. VVER (Older Designs)