TRACE/PARCS Analysis of ATWS with Instability for a MELLLA+BWR/5
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Nuclear Regulatory Commission, Washington, DC (United States)
A TRACE/PARCS model has been developed to analyze anticipated transient without SCRAM (ATWS) events for a boiling water reactor (BWR) operating in the maximum extended load line limit analysis-plus (MELLLA+) expanded operating domain. The MELLLA+ domain expands allowable operation in the power/flow map of a BWR to low flow rates at high power conditions. Such operation exacerbates the likelihood of large amplitude power/flow oscillations during certain ATWS scenarios. The analysis shows that large amplitude power/flow oscillations, both core-wide and out-of-phase, arise following the establishment of natural circulation flow in the reactor pressure vessel (RPV) after the trip of the recirculation pumps and an increase in core inlet subcooling. The analysis also indicates a mechanism by which the fuel may experience heat-up that could result in localized fuel damage. TRACE predicts the heat-up to occur when the cladding surface temperature exceeds the minimum stable film boiling temperature after periodic cycles of dryout and rewet; and the fuel becomes “locked” into a film boiling regime. Further, the analysis demonstrates the effectiveness of the simulated manual operator actions to suppress the instability.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- American Nuclear Society; Nuclear Regulatory Commission/Non-NUREG, Washington, DC (United States); USDOE
- Grant/Contract Number:
- SC0012704
- OSTI ID:
- 1239794
- Alternate ID(s):
- OSTI ID: 1263905
- Report Number(s):
- BNL--111742-2016-JA; BNL--112141-2016-JA
- Journal Information:
- Nuclear Technology, Journal Name: Nuclear Technology Journal Issue: 2 Vol. 196; ISSN 0029-5450
- Publisher:
- American Nuclear Society (ANS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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