IRRADIATION PERFORMANCE OF MODIFIED-316 STAINLESS-STEEL FOR MONJU FUEL

Neutron irradiation behavior of PNC316 stainless steel, which has been developed for prototype fast breeder reactor MONJU, was investigated up to a maximum dose of 185 dpa. Excellent swelling and creep properti es of PNC316 were confirmed and are believed to be the best among this class of austenitic stainless steels. Performance of a Monju type fue l assembly was demonstrated at conditions more severe than those antic ipated in Monju. Significant improvement in the swelling resistance of PNC316 was mainly due to the formation of a stable phosphide that tra ps helium bubbles and retards the conversion of bubbles to voids. Tita nium or increased silicon addition apparently extended the dose for th e phosphide dissolution and thus extended the swelling incubation peri od.