• The transition phase requires providing sufficient, portable, onsite equipment and consumables to maintain or restore these functions until they can be accomplished with resources brought from off site.
• The final phase requires obtaining sufficient offsite resources to sustain those functions indefinitely.
The FLEX implementation guide (NEI, 2012) contains these elements and was endorsed in USNRC Interim Staff Guidance (USNRC, 2012c) as being an acceptable means of complying with the Mitigation Strategies Order. The only caveat was that for the initial phase of the response, a determination of appropriate response time had to be made and used in the selection of storage location and readiness of equipment. The USNRC will review each plant’s FLEX installation and guidance as they are being completed (which will be no later than the end of 2016) and will issue a safety evaluation report.
H.4.2 Revision of SAMG
The Electric Power Research Institute commissioned a revision to the Severe Accident Management Guidance Technical Basis Report (EPRI, 2012b). This report is the first update of the original 1991 version, adding additional Candidate High Level Actions in Volume 1 and providing supporting technical information in Volume 2. New material addresses using seawater injection for reactor core cooling, common-cause failures due to external events, cooling spent fuel pools, setting priorities in multiunit events, containment isolation failure, and hydrogen combustion within plant buildings. The intent, as with the original report, is to guide owners’ groups in developing new SAMG.
Efforts are currently under way to develop revised versions of the SAMG for both generic and plant-specific guidance. The Emergency Procedures Group of the BWR Owners’ Group has been meeting quarterly since the Fukushima Daiichi accident and completed Revision 3 of the generic guidelines in 2013. These are integrated guidance for emergency procedures and severe accidents, referred to as Emergency Procedure Guidelines/Severe Accident Guidelines. According to the Nuclear Energy Institute (Williamson et al., 2013), this revision utilizes both FLEX and EDMGs capabilities and guidance to provide core and spent fuel pool cooling and maintain containment functions. Individual plants are developing EOPs and SAMG based on this generic guidance but tailored to their specific situations. The generic guidance is in the process of being implemented for each plant, and industry workshops are being held in the United States, Europe, Mexico, Japan, and Taiwan to assist with this process. The USNRC has formally requested that