“…SAP, as opposed t o Zircaloy-2, was selected as the cladding for WR-1 because of uncertainty concerning hydriding of J Zi rcaloy-2. Irradiation testing of SAP-clad U02 elements a t kd0 of about 36 W/ cm a t clad temperatures of 450°C -500°C resulted in two significant clad f a i 1 ures . Fai 1 ures occurred only i n 244-cm long rods, a l l of which were clad with SAP-930 which has a lower hoop-s tress rupture strength than M257.…”