Patent ID: 7366644

Claim:
A method of judging practical conditions for use of an ordered structure alloy under an irradiation environment, comprising: preparing an irradiated state diagram that expresses for the ordered structure alloy a relation of a degree of long range order S to a variable R of an irradiated state of the ordered structure alloy, related to a damage rate and an irradiation temperature, on basis of an evaluation formula related to an effect of irradiation on the degree of long range order of the ordered structure alloy under irradiation environments by using as parameters, a first threshold value S th1 at which the degree of long range order begins to decrease, under irradiation, at a rate greater than a rate at which the degree of long range order decreased prior to the first threshold value having been reached, a second threshold value S th2 at which the degree of long range order is nearer to reaching equilibrium than the degree of long range order was prior to the second threshold value having been reached and after decrease of the degree of the long range order which began at the first threshold value S th1 , and the degree of long range order in an equilibrium state S eq ; for irradiation conditions under which the ordered structure alloy is to be used, calculating an R-value, and corresponding to the R-value, finding an S-value, an S th1 -value, an S th2 -value, and an S eq -value; and comparing the S-value, the S th1 -value, the S th2 -value, and the S eq -value, to thereby predict a damage level and a variation condition of the damage level of the ordered structure alloy under the irradiation environment.