CALCULATION OF RADIATION-INDUCED STRESS-RELAXATION

A numerical calculation based on point defect kinetics under stress wa s carried out to evaluate radiation-induced stress relaxation in a sol ution-annealed 316 stainless steel at low and medium temperatures (60 and 300 degrees C). The calculation shows that the stress relaxation r elative to the initial stress is almost independent of the initial str ess under irradiation. At 1x10(-6) dpa/s, stress relaxation at 60 degr ees C is greater than that at 300 degrees C and the stress almost disa ppears in a month of continuous irradiation. Even with a low damage ra te of 1x10(-8) dpa/s, the stress relaxation at 60 degrees C is conside rable and exceeding that at 300 degrees C and 1 x 10(-6) dpa/s during the first several months of irradiation. The results indicate the impo rtance of the radiation-induced stress relaxation in experimental fusi on reactors.