Markov Model of Severe Accident Progression and Management
The earthquake and tsunami that hit the nuclear power plants at the Fukushima Daiichi site in March 2011 led to extensive fuel damage, including possible fuel melting, slumping, and relocation at the affected reactors. A so-called feed-and-bleed mode of reactor cooling was initially established to remove decay heat. The plan was to eventually switch over to a recirculation cooling system. Failure of feed and bleed was a possibility during the interim period. Furthermore, even if recirculation was established, there was a possibility of its subsequent failure. Decay heat has to be sufficiently removed to prevent further core degradation. To understand the possible evolution of the accident conditions and to have a tool for potential future hypothetical evaluations of accidents at other nuclear facilities, a Markov model of the state of the reactors was constructed in the immediate aftermath of the accident and was executed under different assumptions of potential future challenges. This work was performed at the request of the U.S. Department of Energy to explore 'what-if' scenarios in the immediate aftermath of the accident. The work began in mid-March and continued until mid-May 2011. The analysis had the following goals: (1) To provide an overall framework for describing possible future states of the damaged reactors; (2) To permit an impact analysis of 'what-if' scenarios that could lead to more severe outcomes; (3) To determine approximate probabilities of alternative end-states under various assumptions about failure and repair times of cooling systems; (4) To infer the reliability requirements of closed loop cooling systems needed to achieve stable core end-states and (5) To establish the importance for the results of the various cooling system and physical phenomenological parameters via sensitivity calculations.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE NE OFFICE OF NUCLEAR ENERGY (NE)
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1039654
- Report Number(s):
- BNL-96959-2012-CP; R&D Project: 15805; TRN: US1202226
- Resource Relation:
- Conference: PSAM 11 ; Helsinki, Finland; 20120625 through 20120629
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
ACCIDENT MANAGEMENT
ACCIDENTS
COOLING SYSTEMS
EARTHQUAKES
MANAGEMENT
MELTING
NUCLEAR FACILITIES
NUCLEAR POWER PLANTS
RELIABILITY
REPAIR
SENSITIVITY
TSUNAMIS
MARKOV PROCESS
Accident Management
Severe Accidents
Markov Model