Depressurization as an accident management strategy to minimize the consequences of direct containment heating [electronic resource].

Published:: Rockville, Md. : U.S. Nuclear Regulatory Commission, 1990.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description:: Pages: (120 pages) : digital, PDF file
Additional Creators:: U.S. Nuclear Regulatory Commission and United States. Department of Energy. Office of Scientific and Technical Information

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Summary:

Probabilistic Risk Assessments (PRAs) have identified severe accidents for nuclear power plants that have the potential to cause failure of the containment through direct containment heating (DCH). Prevention of DCH or mitigation of its effects may be possible using accident management strategies that intentionally depressurize the reactor coolant system (RCS). The effectiveness of intentional depressurization during a station blackout TMLB' sequence was evaluated considering the phenomenological behavior, hardware performance, and operational performance. Phenomenological behavior was calculated using the SCDAP/RELAP5 severe accident analysis code. Two strategies to mitigate DCH by depressurization of the RCS were considered. One strategy, called early depressurization, assumed that the reactor head vent and pressurizer power-operated relief valves (PORVs) were latched open at steam generator dryout. The second strategy, called late depression, assumed that the head vent and PORVs were latched open at a core exit temperature of ∼922 K (1200°F). Depressurization of the RCS to a low value that may mitigate DCH was predicted prior to reactor pressure vessel breach for both early and late depressurization. The strategy of late depressurization is preferred over early depressurization because there are greater opportunities to recover plant functions prior to core damage and because failure uncertainties are lessened. 22 refs., 38 figs., 6 tabs.

Report Numbers:

E 1.99:nureg/cr-5447
E 1.99: egg--2574
egg--2574
nureg/cr-5447

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Note:

Published through SciTech Connect.
10/01/1990.
"nureg/cr-5447"
" egg--2574"
"TI91002467"
Miller, J.D.; Chambers, R.; Hanson, D.J.; Dobbe, C.A.; Golden, D.W.; Hallbert, B.P.

Funding Information:

AC07-76ID01570

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