BWR LOSS of Coolant Integral Tests with Two Bundle Loop, (II) Effect of ECCS Activation Modes on Thermal-Hydraulic Characteristics

Abstract

Simulation tests of a BWR loss-of-coolant accident (LOCA) by a postulated full size, double-ended break of a recirculation suction line were conducted using the Two Bundle Loop (TBL) with two full size, electrically heated bundles. In the tests, single failure of emergency core cooling systems (ECCSs) was assumed. The following results were obtained from the tests:

(1) The rods heated up early in one of the two bundles, while heatup initiations were delayed in the other. The difference was observed for any ECCS activation mode.

(2) The peak cladding temperature (PCT) of each bundle was expressed as a linear function of integrated power during the heatup period.

(3) The highest PCT in the tests was 861 K under the assumption of an HPCS (high pressure core spray) failure, which was well below the licensing limitation of 1,473 K.

KEYWORDS:

• BWR type reactors
• loss of coolant
• ECCS
• double-ended break
• recirculation suction line
• thermal hydraulic difference
• parallel bundles
• peak cladding temperature