The compatibility of the direct use of spent pressurized water reactor fuel in Canada deuterium uranium (CANDU) reactor (DUPIC) fuel with the existing 713-MW(electric) CANDU (CANDU-6) reactor has been analyzed for large-break loss-of-coolant-accident (LOCA) scenarios such as a 55% pump suction break, a 35% reactor inlet header break, and a 100% reactor outlet header break. The compatibility was assessed for the fuel integrity against the stored energy and the radiation environmental effect resulting from the large-break LOCA. The analysis showed that the stored energy of the DUPIC fuel was below the fuel breakup energy by 32%. The environmental effect was estimated for the personal and public doses using the radiation source term obtained from one-fourth of the fission product inventory in the fuel gap of the CANDU-6 reactor, being steadily operated at full power. The analyses have shown that both the personal and population doses are below the design limits even for a postulated dual failure such as a complete loss of containment building isolation logic.