Mass Spectroscopic Measurements of Fission Product Vaporization from Irradiated LWR Fuel
Irradiated light water reactor (LWR) fuel from the BR3 reactor was thermally annealed up to 2500 K in a Knudsen-cell, and the effusing vapours were measured by mass spectrometry. The experiments provide data on the stoichiometry evolution of the fuel during release as well as a reliable method to evaluate the diffusion coefficients of volatile and less volatile fission products. The analysis of the data starts from diffusion of xenon, which clearly shows 3 typical release stages respectively controlled by radiation damage annealing, self diffusion and matrix vaporization. The experimental measurements are also in agreement with the predictions of intragranular trapping models. Barium and caesium showed faster release than xenon, the former being likely diffusing atomically to the grain boundaries where no evidence of formation of stable zirconates was found. These results were compared with those obtained by a burnup simulated fuel, where barium was initially present in a perovskite phase, producing essentially different release patterns.
Bibliographic Reference: Article: Nuclear Technology (1995)
Record Number: 199512115 / Last updated on: 1996-01-15
Original language: en
Available languages: en