Nuclear fuel element and manufacturing method therefor

A region partitioning inner tube is contained in a metal cladding tube to partition the inside of the cladding tube to a central region and a circumferential region, and granular fuel materials or fuel fertile materials are filled in the metal cladding tube and sealed. If the kinds, grain size and mixing ratio of the granular fuel materials, fuel fertile materials or non-fuel materials to be filled are selected, various kinds of nuclear fuel elements can be manufactured simply and easily without complicating the fuel manufacturing step. It can be used in common to the entire of fuel cycles in order to effectively utilize uranium resources as fuels for LBW or FBW type reactors. Nuclear fuel elements with high degree of freedom can thus be obtained simply and easily while keeping uranium enrichment degree of granular fuel materials uniformly by optionally selecting the diameter of the inner tube in relation with the diameter of the cladding tube while taking nuclear thermal characteristics into consideration. (N.H.)