FUEL ASSEMBLY FOR PRESSURIZED WATER REACTOR

摘要

PROBLEM TO BE SOLVED: To prevent increase of a gap space existing between fuel assemblies incorporated in a nuclear reactor pressure vessel without reinforcing a fuel assembly structure in regard to a fuel assembly for a pressurized water reactor provided with a control rod guide tube 12, a head part 6, a leg part 7 and fuel rods 9 respectively held transversely by a multiplicity of cells 13 of spacers 10 and fixed to an upper core grid 4 and a lower core grid 5 by the head part and the leg part inside the nuclear reactor pressure vessel. SOLUTION: At least one spacer 10 has a first part 15 which lies on a radially outer side with respect to a longitudinal center axis of the fuel assembly and a second part 16 which lies on a radially inner side and is completely surrounded by the first part. The second part is formed of zircaloy and the first part is made of a metallic material with a higher coefficient of thermal expansion and lower growth in the radial direction induced by neutron irradiation when compared to the zircaloy of the second portion.