To prevent the occurrence of elongation and warpage deformation, caused by irradiation growth, by specifying the rate of orientation of a specific crystal orientation of hexagonal Zr of allot in a direction perpendicular to the plate surface.
Warpage deformation is caused by the orientation of the <0001> crystal orientation of hexagonal Zr metal in a direction perpendicular to the surface of Zr alloy. On neutron irradiation, the crystal is contracted in the <0001> direction and expands in a direction perpendicular to the <0001> direction. As a result, in the case of a fuel channel box in which the <0001> crystal orientation is oriented perpendicularly to the surface, irradiation growth occurs in a longitudinal direction and a width direction, If the amount of irradiation differs in different positions, difference in the amount of irradiation growth is bright about and causes warpage deformation. In this case, by regulating the rate of orientation, Fr as of the <0001> crystal orientation on a direction perpendicular to the plate surface is regulated to 0.20-0.50, irradiation elongation is remarkably decreased and, even in a high irradiation region of 1022(n/cm2) amount of neutron irradiation, elongation is reduced essentially to zero, that is, the occurrence of warpage deformation can be prevented.
SUGANO MASAYOSHI
TAKASE IWAO
KIDA TOSHITAKA
ONAKA NORIYUKI
ISHIZAKI HIDEAKI
HIRAKAWA HIROMASA
MAKI HIDEO