Preventing water inflow to fuel element during reactor vault flooding - by fission gas pressure rise esp. produced by automatically closing valves

摘要

An inflow of water into fuel elements inside a flooded reactor vault esp. for gas-cooled, fast reactors where fission gas can be removed from the fuel elements through intended leakage points at the junction between the fuel element casing and the core support structure is prevented. While the reactor vault is flooded, the fission gas removal system is subjected to a gas pressure higher than the water pressure at the intended leakage point. Specifically, the parts of the fission gas removal system that are located inside individual fuel elements are each shut off on the upstream side of the intended leakage point be means of a valve system operated as a function of the pressure and temp. on the two sides of this point. Used esp. for a gas-cooled fast reactor where fission prods. are led off from the fuel elements to an extn. system. The arrangement enables the reactor vault to be flooded without water entering fuel elements.