Assessment of the potential for high-pressure melt ejection resulting from a Surry station blackout transient
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
Containment integrity could be challenged by direct heating associated with a high pressure melt ejection (HPME) of core materials following reactor vessel breach during certain severe accidents. Intentional reactor coolant system (RCS) depressurization, where operators latch pressurizer relief valves open, has been proposed as an accident management strategy to reduce risks by mitigating the severity of HPME. However, decay heat levels, valve capacities, and other plant-specific characteristics determine whether the required operator action will be effective. Without operator action, natural circulation flows could heat ex-vessel RCS pressure boundaries (surge line and hot leg piping, steam generator tubes, etc.) to the point of failure before vessel breach, providing an alternate mechanism for RCS depressurization and HPME mitigation. This report contains an assessment of the potential for HPME during a Surry station blackout transient without operator action and without recovery. The assessment included a detailed transient analysis using the SCDAP/RELAP5/MOD3 computer code to calculate the plant response with and without hot leg countercurrent natural circulation, with and without reactor coolant pump seal leakage, and with variations on selected core damage progression parameters. RCS depressurization-related probabilities were also evaluated, primarily based on the code results.
- Research Organization:
- Nuclear Regulatory Commission, Washington, DC (United States). Div. of Systems Research; EG and G Idaho, Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- Nuclear Regulatory Commission, Washington, DC (United States)
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 10108308
- Report Number(s):
- NUREG/CR-5949; EGG-2689; ON: TI94004046; TRN: 94:001451
- Resource Relation:
- Other Information: PBD: Nov 1993
- Country of Publication:
- United States
- Language:
- English
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Intentional depressurization accident management strategy for pressurized water reactors
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Related Subjects
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
SURRY-1 REACTOR
BLACKOUTS
MELTDOWN
SURRY-2 REACTOR
SURRY-3 REACTOR
SURRY-4 REACTOR
TRANSIENTS
REACTOR SAFETY
HEAT TRANSFER
HYDRAULICS
CORIUM
REACTOR COOLING SYSTEMS
CONTAINMENT
HEATING
S CODES
R CODES
COMPUTER CALCULATIONS
DEPRESSURIZATION
220900
210200
POWER REACTORS
NONBREEDING
LIGHT-WATER MODERATED
NONBOILING WATER COOLED