Technical issues for safety improvement 2. Validation of effectiveness of heat removal using SG secondary system in PWR

Cooling with steam generator (SG) secondary system is one of the most important AM measures for PWR because that makes it possible to remove the core decay heat without losing the inventory of the primary system and to reduce pressure of the primary system promoting coolant injection by low-pressure injection equipment in the case of LOCA. Effectiveness of the cooling using SG secondary system has been indicated by various integrated system tests, but the data that can cover a wide range of SA scenarios is insufficient, for example when the primary system inventory is small or core decay heat is small. This paper summarizes typical subjects relating to the SG secondary-side depressurization and shows some recent activities to expand the database for the validation of BE analytical methods. (author)