Verifiaction of core exit temperature for adquate SAMG entry condition of OPR1000

Abstract

Various core exit temperature (CET) values set as Severe Accident Management Guidance (SAMG) entry conditions from the points of view of delaying reactor pressure vessel (RPV) failure time and available operator?s action time were investigated for Korean Optimized Power Reactor (OPR) 1000. CET is widely used for judging a proper entry condition to SAMG. The CET can inform the core damage, uncovery and superheat level of core. Level 2 probabilistic safety assessment (PSA) code MELCOR 1.8.6 is used for postulated scenarios; small break loss of coolant accident without safety injection (SBLOCA without SI), station black out (SBO), and total loss of feed water (TLOFW). In view of delaying RPV failure time, SAMG entry condition of CET reaching 923K results in the best for SBLOCA without SI and SBO among selected CET conditions. However, for TLOFW, the best result is observed when the SAMG entry condition is applied with CET of 838K. From a standpoint of available operator's action time, there was no significant difference between selected SAMG entry conditions. For these reasons, the adequacy of current CET limit as SAMG entry conditions and the relationship between CET and quantity of oxidation heat are worth to research.