Non-Free Swelling of Uranium Dioxide Fuel at Burnup 8–13% h.a.

Abstract

The porosity and rate of non-free swelling of the fuel in fast-reactor fuel elements with EK-164ID c.d. steel cladding were measured by hydrostatic and metallographic methods. It was shown that the rate of swelling of uranium dioxide trends downward with increasing burnup. A restraining factor of non-free swelling is fuel-kernel restructuring, which stabilizes the natural increase of the closed porosity of fuel in contact with cladding. The rate of non-free swelling of fuel at maximum burnup 13% h.a. is 0.6–0.8% per 1% burnup.