Nuclear Reactor Power Systems

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Nuclear Reactor Power Systems

• Dwight L. Williams, Ph.D., P.E.
• Potomac Chapter
• Maryland Society of Professional Engineers
• 27 October 2005

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Overview

• Introductions
• Categories of Nuclear Reactors
• Nuclear Power Accidents
• Summary and Nuclear Power Systems Q/A
• General Q/A

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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

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Power Systems
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Nuclear Primer

• Subatomic Particles
• Concept of Isotopes
• Concept of Half-Life
• Types of Radiation

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Subatomic Particles
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Concept of Isotopes
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Concept of Half-Life
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Types of Radiation
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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

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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

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BWR
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PWR
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VVER
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Heavy Water Reactors

• Canadian Deuterium-Uranium (CANDU) Reactors
• Use natural (non-isotopically concentrated)
  uranium
• Tmax 590oF PRxr Coolant 1500 psi
• Can run 2 ½ years without refueling/downtime
• RBMK Reactors
• Chernobyl-style reactor
• Graphite and D2O in reactor core
• Much improved designs today

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CANDU Reactor
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RBMK Reactor
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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

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LMFBR
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AGR
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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 operators ability to
  impede automated emergency systems

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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 operators ability to
  impede automated emergency systems

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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

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For More Information

• Visit The Virtual Nuclear Tourist website at
  http//www.nucleartourist.com
• E-mail Dwight Williams at mdyoungengineer_at_nspe.org

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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

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VVER (Older Designs)