This paper describes an experimental irradiation assembly and associated instrumentation which has been developed and successfully utilized for the performance of dynamic, in-reactor low cycle fatigue tests of reactor pressure vessel steels. The equipment provides for the simultaneous reverse bend testing of as many as 15 sheet-type specimens representing a range of strain amplitudes at controlled temperatures in the range of 300 to 700 F.

The results of an exploratory investigation on the fatigue resistance of ASTM A302-B steel during irradiation at 500 F are presented and compared with data from out-of-reactor control tests.