The PFR-TREAT collaborative program of transient safety testing of fast reactor fuel was established in 1979 to provide mutual advantage to USDOE and the UKAEA through irradiation of US and UK full-length fuel pins in PFR, followed by safety testing in TREAT. The tests which were planned include Transient Over-Power (TOP) and Transient Under-Cooling with Over-Power (TUCOP) tests to fuel destruction and re-distribution; the results will provide significant new information on fuel and cladding behavior in hypothetical reactor faults. The information obtained in both US and UK fuel pins is to be interpreted by both partners and published jointly when mutually agreed. Thirteen tests, on fresh and irradiated fuel, in single-pin and 7-pin test sections, were completed by the end of 1983. The test matrix, which is currently being re-evaluated, calls for additional tests to be run under the present agreement. There has been an extensive program of post irradiation examination of sibling pins in both the UK and the US to characterize the test fuel prior to destructive irradiation, including testing of irradiated cladding to determine its failure characteristics
