Nuclear fuel assembly

Purpose: To enable to average the releasing amount of gaseous nuclear fission products from fuel pellets on each of nuclear fuel elements. Constitution: In a nuclear fuel assembly comprising a plurality of nuclear fuel elements bundled together each composed of a fuel can sealingly filled with nuclear fuel substances, the amount of inert gases to be sealed previously within the fuel cans, in at least one of fuel elements incorporated with burnable poisons and nuclear fuel elements situated in adjacent with control rods, is made larger than the amount of the inert gas incorporated within the fuel cans in other nuclear fuel elements. In such a constitution, release of the gaseous fission products from the fuel pellets due to the relative power-up can be suppressed. (Aizawa, K.)