16.2 - Severe Accident Analysis (RRC-B) - EDF Hinkley Point

SUB-CHAPTER : 16.2PRE-CONSTRUCTION SAFETY REPORTCHAPTER 16: RISK REDUCTION AND SEVEREACCIDENT ANALYSESPAGE : 57 / 295Document ID.No.UKEPR-0002-162 Issue 04SECTION 16.2.2.1 - TABLE 12Relevant scenarios for high pressure core melt prevention [Ref]Kind of Scenario Relevant Scenario Reasons for the ChoiceCore melt scenarioswithout in-vesselrefloodingCore melt scenarioswith in-vesselrefloodingLOOP (unavailabilityof 6 DG) full powerreactor state ATLOFW withunavailability of feed isa scenario with anegligible likelihood.Full power reactorstate ALOOP with SIrecoveryTLOFW with delayedRCS depressurisationand refloodingHigh energy to be released only withbleed capacity, most severe for RCP[RCS] pressure level (no break otherthan bleed discharge; no SG heatremoval)Bound all core melt scenarios withbreaks or/and with SG heat removalHighest energy in RCP [RCS] (latereactor trip and pumps stop).However in the context of a deterministicapproach with identification of margins,the available time to successfullydepressurise such scenario is alsostudied.Bound all scenarios with late reflooding(most severe for pressure level becauselowest discharge capacity: bleed valveonly)Highest energy in RCP [RCS] (latereactor trip and pumps stop)