Analysis of an Out-of-pile Experiment for Materials Redistribution under Core Disruptive Accident Condition of Fast Breeder Reactors

Abstract

Calculation of one of the SIMBATH experiments was performed using the SIMMER-II code. The experiments were intended to simulate the fuel pin disintegration, the molten materials relocation and following materials redistribution that could occur during core disruptive accidents assumed in fast breeder reactors. The calculation by SIMMER-II showed that the incorporated step-wise fuel pin disintegration model and the modified particle jamming model were capable of reproducing the course of materials relocation within the identified ranges of the parameters which governed the blockages formation, i.e. the characteristic radius of solid particles jamming and/or sieving out in the flow and the effective particle viscosity. In particular the final materials redistribution calculated by SIMMER-II very well reproduced the experiment. This fact made it possible to interpret theoretically the mechanisms of flow blockages formation and related materials redistribution.

KEYWORDS:

• fast breeder reactor
• core disruptive accident
• transition phase
• out-of-pile experiment
• SIMBATH
• SIMMER-II
• computer codes
• parametric analysis
• material relocation
• particle jamming
• Row blockage
• material redistribution