CALCULATION OF RADIATION-INDUCED CREEP AND STRESS-RELAXATION

Numerical calculation based on a computer simulation of point defect k inetics under stress was performed to predict radiation-induced deform ation in an Inconel X-750 bolt in a LWR core and for a 316 stainless s teel blanket in experimental fusion reactors with the water-coolant sc enario. Although the displacement rate is rather low, modest irradiati on creep with nearly linear stress dependence was predicted below 200 MPa at 300 degrees C in the LWR core. This low stress dependence cause s significant stress relaxation, which coincides with the experimental data to 2 dpa. An almost equal amount of enhanced irradiation creep s train was predicted at 60 degrees C in both solution annealed and cold worked 316 stainless steel in the water-cooled blanket. The stress re laxation is practically not expected without irradiation in both the c ases, but the calculation predicts that it is definitely expected unde r irradiation.