https://orcid.org/0000-0002-5917-0317
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Abstract
The Boiling Water Reactor Owner’s Group released Emergency Procedure Guidelines and Severe Accident Guidelines Revision 4 (EPG/SAG Rev. 4) in 2018. The major improvement to EPG/SAG Rev. 4 was Contingency 1 (Alternate Level/ Pressure Control). Contingency 1 coordinates the reactor pressure vessel (RPV) water level and RPV pressure control action to prolong the availability of steam-driven injections and optimize the transfer to motor-driven systems.
In this study, the effectiveness of the EPG/SAG Rev. 4 Contingency 1 strategy was compared with those of EPG/SAG Revision 2 Contingency 1 and Specific Major Incident Guidelines (SMI) using the Modular Accident Analysis Program, Version 5 (MAAP5). SMI was developed by the Taiwan Power Company to mitigate a Fukushima-like accident. The surrogate plant that analyzed is the Kuosheng Nuclear Power Plant (NPP). The Kuosheng NPP is BWR-6 Mark-III containment. MAAP5 is an integral severe accident analysis program that simulates the responses of a light water reactor power plant during a severe accident. This program has been used extensively for probabilistic risk assessments and for verification and validation of mitigation actions specified in severe accident management guidelines.
The simulation scenarios were extended loss of alternative-current power and loss of ultimate heat sink. The low-capacity, motor-driven portable pump was the only available system for RPV injection in the first hour of the accident. In this time period, the RPV water level and pressure were controlled by reactor core isolation cooling and safety relief valves. After this study, the strategy of EPG/SAG Rev. 4 Contingency 1 was successfully validated, and the effectiveness of minimum pre-depressurization RPV water level and the low-capacity, motor-driven portable pump were also demonstrated in this study.
Acronyms
| ADS: | = | automatic depressurization system |
| BWROG: | = | Boiling Water Reactor Owner’s Group |
| ECCS: | = | emergency core cooling system |
| EDG: | = | emergency diesel generator |
| ELAP: | = | extended loss of ac power |
| EOPs: | = | emergency operation procedures |
| EPG/SAG: | = | Emergency Procedure Guidelines/Severe Accident Guidelines |
| FLEX: | = | diverse and flexible coping strategies |
| HPCS: | = | high-pressure cooling system |
| LUHS: | = | loss of ultimate heat sink |
| MPDRWL: | = | minimum pre-depressurization reactor water level |
| MSCRWL: | = | minimum steam cooling reactor water level |
| MSIV: | = | main steam line isolation valve |
| NPP: | = | nuclear power plant |
| PCT: | = | peak cladding temperature |
| RCIC: | = | reactor core isolation cooling |
| RPV: | = | reactor pressure vessel |
| SBO: | = | station blackout |
| SMI: | = | Specific Major Incident Guidelines |
| SRV: | = | safety relief valve |
| TAF: | = | top of active fuel |
| TPC: | = | Taiwan Power Company |
Acknowledgments
The authors would like to thank the Institute of Nuclear Energy Research’s researchers for their support in this study. The authors also are grateful to the operators of the Kuosheng NPP for their assistance with the simulator work.
Disclosure Statement
No potential conflict of interest was reported by the authors.