Characterization of irradiated simulated DUPIC fuel

Abstract

A simulated DUPIC (Direct Use of Spent PWR Fuel in CANDU Reactors) fuel was irradiated at HANARO research reactor of KAERI in 1999. Post-irradiation examinations, such as measurements of γ-scanning, profilometry, density, hardness, microstructure, and fission product distribution were performed on the irradiated simulated DUPIC fuel. In γ-scanning, the intensity along the axial direction was sharply decreased at the areas between the pellets. There was no significant change in the profilometry of SEU-1.47%, but variation was detected in SEU-2.19%+F.P by 67 μm, and the peaks precisely coincided with the ridges of the pellets. The marked difference between SEU-1.47% and SEU-2.19%+F.P pellets after irradiation was the configuration of cracks arised in the pellets. Some large equiaxed grains of 11.1 μm were observed at the center of the SEU-2.19%+F.P pellet, while the grain size near the surface of the pellet was remained almost the same as the original grain size of 5.58 μm. The hardness had no tendency toward change to the direction, but average hardness was increased as much as 10% compared with a fresh simulated DUPIC fuel.

Behavior of metallic precipitate in an irradiated simulated fuel

“…Previous studies by adopting a post-irradiation test have been performed for an irradiated DUPIC (Direct Use of Spent PWR Fuel in CANDU Reactors) fuel, which was fabricated from spent fuel with an oxidation and a reduction process [2][3][4]. Because a fission product affects the electric and thermal conductivities of a fuel, a large quantity of it changes the fuel performance of a fuel especially for high burn-up fuels, therefore, characterizing a metallic precipitate through a post irradiation examination is important.…”