Evaluation of MELCOR improvements: Peach Bottom station blackout analyses
Long-term station blackout analyses in Peach Bottom were first carried out using MELCOR 1.8BC, and later with 1.8DN, as part of an overall program between the US Nuclear Regulatory Commission (NRC) and Brookhaven National Laboratory (BNL), to provide independent assessment of MELCOR as a severe accident/source term analysis tool. In addition to the reference MELCOR calculation, several sensitivity calculations were also performed to explore the impact of varying user-input modeling and timestep control parameters on the accident progression and radionuclide releases to the environment calculated by MELCOR. An area of concern that emerged from these studies was the impact of the selection of maximum allowable timestep ({Delta}t{sub max}) on the calculational behavior of MELCOR, where the results showed significant differences in timing of key events, and a lack of convergence of the solution with reduction of {Delta}t{sub max}. These findings were reported to the NRC, SNL, and the MELCOR Peer Review Committee. As a consequence, a significant effort was undertaken to eliminate or mitigate these sensitivities. The latest released version of MELCOR, Version 1.8.2, released in April 1993, contains several new or improved models, and has corrections to mitigate numerical sensitivities. This paper presents the results of updating the earlier sensitivity studies on maximum timestep, to more properly represent the abilities of the improved MELCOR version 1.8.2. Results are presenter in terms of timing of key events, thermal-hydraulic response of the system, and environmental release of radionuclides. The impact of some of the newer models, such as falling debris quench model, and ORNL`s new BH model, is also evaluated.
- Research Organization:
- Brookhaven National Lab., Upton, NY (United States)
- Sponsoring Organization:
- Nuclear Regulatory Commission, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 10170157
- Report Number(s):
- BNL-NUREG-49201; CONF-931079-29; ON: DE94015820; TRN: 94:016595
- Resource Relation:
- Conference: 21. water reactor safety information meeting,Bethesda, MD (United States),25-27 Oct 1993; Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
PEACH BOTTOM-1 REACTOR
REACTOR ACCIDENTS
M CODES
HEAT TRANSFER
RADIONUCLIDE MIGRATION
BLACKOUTS
SENSITIVITY ANALYSIS
220900
990200
220504
REACTOR SAFETY
MATHEMATICS AND COMPUTERS
DESIGN BASIS AND HYPOTHETICAL ACCIDENTS