Operational Reactor Safety - MIT OpenCourseWare Reactor Safety 22.091/22.903 Professor Andrew C....
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Prof. Andrew C. Kadak, 2008 Page 1 Department of Nuclear Science & Engineering Operational Reactor Safety 22.091/22.903 Professor Andrew C. Kadak Professor of the Practice Safety Systems and Functions Lecture 9
Transcript of Operational Reactor Safety - MIT OpenCourseWare Reactor Safety 22.091/22.903 Professor Andrew C....
Prof. Andrew C. Kadak, 2008Page 1Department of Nuclear Science & Engineering
Operational Reactor Safety22.091/22.903
Professor Andrew C. KadakProfessor of the Practice
Safety Systems and FunctionsLecture 9
Prof. Andrew C. Kadak, 2008Page 2Department of Nuclear Science & Engineering
Topics to be Covered• Fundamentals of Safety
– Introduction to Safety Analysis
– Defense in Depth
– Design Basis Accidents
– Beyond Design Basis Accidents
– Safety Systems
– Emergency Safeguards Systems
– Containment
Prof. Andrew C. Kadak, 2008Page 3Department of Nuclear Science & Engineering
Key Safety Measures• Prevention
– Proper Design and Training• Protection
– Monitoring and Control Systems– Active shutdown and cooling systems
• Mitigation – limit consequences– Engineered Safety Systems
Called Defense in Depth Approach
Prof. Andrew C. Kadak, 2008Page 4Department of Nuclear Science & Engineering
Energy Sources• Stored Energy in Fuel, Steam and Structures• Energy from nuclear transients• Decay Heat• Chemical Reactions• External events – seismic, tornadoes,
hurricanes, etc.
Prof. Andrew C. Kadak, 2008Page 5Department of Nuclear Science & Engineering
Mission - Remove Heat• Prevent fuel cladding failure or core melting
– Install systems to do this under many transient and accident conditions
• If unsuccessful, keep radioactive materials in the containment
– Assure containment function is maintained and not breached by overpressure or missiles
• If unsuccessful, limit releases• If unsuccessful, implement emergency plan
Prof. Andrew C. Kadak, 2008Page 6Department of Nuclear Science & Engineering
Design Basis Accidents• Overcooling• Undercooling• Overfilling• Loss of Flow• Loss of Coolant• Reactivity• Anticipated Transients without Scram• Spent fuel or handling events• External Events
Prof. Andrew C. Kadak, 2008Page 7Department of Nuclear Science & Engineering
Energetic Reactions in Reactors
Courtesy of MIT Press. Used with permission.
Prof. Andrew C. Kadak, 2008Page 8Department of Nuclear Science & Engineering
PrimaryCoolant Pump
PrimaryVessel
ControlRods
ReactorCore
292ÞC
PrimaryConcrete
Shield15.5 MPa
Pressurizer
324ÞC
SteamGenerator
Concrete and SteelContainment
Primary Side Secondary Side
Steam to Turbine6.9 MPa285ÞC
High-PressureHeaters
Low-PressureHeaters
FeedPump
CondensatePump
Turbine
Turbine Bypass
ElectricGenerator
Grid
Condenser
CoolingTower
-40ÞC-15ÞC
Pressurized Water Reactor Schematic
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Prof. Andrew C. Kadak, 2008Page 9Department of Nuclear Science & Engineering
Specific Design Basis Accidents• Steam line break
• Loss of Flow
• Loss of heat sink
• Steam generator tube(s) rupture
• Control rod ejection or rapid withdrawal
• Anticipated Transients without Scram
• Pressurized thermal shock
• Loss of coolant
– Double ended guillotine break
– Small Break
Prof. Andrew C. Kadak, 2008Page 10Department of Nuclear Science & Engineering
Typical PWR
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Prof. Andrew C. Kadak, 2008Page 11Department of Nuclear Science & Engineering
Severe Accidents• Beyond Design Basis
– Successive failures of the engineering safety systems
– Looking for cliff edge effects that may need to be addressed if consequences are severe and scenario is plausible.
– Core Melt scenarios - vaporization• Steam explosion• Hydrogen explosion• Fission product inventory for release
Prof. Andrew C. Kadak, 2008Page 12Department of Nuclear Science & Engineering
Fission Products for Release
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Prof. Andrew C. Kadak, 2008Page 13Department of Nuclear Science & Engineering
Loss of Coolant Accident Sequence
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Prof. Andrew C. Kadak, 2008Page 14Department of Nuclear Science & Engineering
Engineered Safety Systems
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Prof. Andrew C. Kadak, 2008Page 15Department of Nuclear Science & Engineering
PWR Engineered Safety Systems
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Prof. Andrew C. Kadak, 2008Page 16Department of Nuclear Science & Engineering
PWR Containment
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Prof. Andrew C. Kadak, 2008Page 17Department of Nuclear Science & Engineering
Containment Pressure Response
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Prof. Andrew C. Kadak, 2008Page 18Department of Nuclear Science & Engineering
BWR Early Engineered Safety Systems
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Prof. Andrew C. Kadak, 2008Page 19Department of Nuclear Science & Engineering
Early BWR Containment Design
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Prof. Andrew C. Kadak, 2008Page 20Department of Nuclear Science & Engineering
Later Version of BWR Containment
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Prof. Andrew C. Kadak, 2008Page 21Department of Nuclear Science & Engineering
Containment Leakage• Function of event and chemistry in building• Driven by containment pressure• Source terms
– Noble gases – not captured– Elemental iodine – reactive and plated out– Organic iodides – not chemically reactive– Particulates and aerosols – heavy settle out
• What is not chemically reacted in containment, plated out or settled out is available for release.
Prof. Andrew C. Kadak, 2008Page 22Department of Nuclear Science & Engineering
Reading and Homework Assignment
1. Read Knief Chapter 13
2. Problems: 13.3, 13.5, 13.8, 13.12 Extra: 13.11
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22.091 Nuclear Reactor SafetySpring 2008
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