Influence of neutron exposure, chemical composition and metallurgical condition, on the irradiation shift of reactor pressure vessel steels

The work described in this paper is part of a continuing program to produce well-characterized data for use in the development of models for the prediction of irradiation shift in pressurized water reactor steels. Results are presented for around 50 batches of Charpy specimens, irradiated either in the DIDO or PLUTO heavy water, or in the HERALD light water, research reactors, to doses up to 35 mdpa (approx. 2 x 1019) n/cm2, E > 1 MeV). The materials include A533B plate, weld, and heat affected zones. The results are compatible with a log/log relationship between dose and shift with an exponent of 0.5 for all materials. They also show that irradiation response is dependent on heat treatment condition. If it is assumed that the Varsik and Byrne Chemistry Relationship, or a similar expression, is an appropriate parameter to characterize the effect of chemical composition on irradiation sensitivity, the results also demonstrate a difference between plate and weld irradiation sensitivity. An empirical model of the data has been developed and assessed, and this is compared with the Odette physically-based irradiation damage model