Applicability of Reactor Vessel Auxiliary Cooling System for FBRs.

Reactor Vessel Auxiliary Cooling System (RVACS) is a simple and passive decay heat removal system for FBRs. However the heat removable capability of this system is small compared to that of immersed type of decay heat exchangers. So, RVACS has limit in applicability up to about 400MWe pool type LMFBR.The objectives of this report are to confirm its heat removal capability, to estimate its applicability limit of this RVACS for FBRs and to evaluate the effects of design parameters. In this report, the plant transient analyses have been performed with thermal-hydraulic code CERES. The main results are as follows:(1) The RVACS with heat collector have large heat removal capability to reduce the peak temperature of primary Coolant by 20°C than that without heat collector.(2) The effects of stack height and level difference of overflow liner on the heat removal capability are not so large.(3) The RVACS with heat collector is applicable up to 500MWe pool type LMFBR.