THE D-COM BLIND PROBLEM ON FISSION GAS RELEASE - THE PREDICTIONS OF THE TRANSURANUS AND FUTURE CODES
The concentration of retained xenon, the percentage of porosity and the UO(2) grain size are measured as a function of radial position in the base irradiated rod AG11-8 and the transient tested rod AG11-10. In the base irradiation, densification of the fuel takes place and slight grain growth occurs at the pellet centre. Gas release is not detected. During the transient test 15-20% of the xenon inventory is released from the fuel grains. Gas release is accompanied in the central region of the fuel by an increase in the porosity. These findings are compared with the predictions made by the fuel performance code TRANSURANUS and are in good agreement. FUTURE is used to investigate the development of gas bubbles and the mechanisms controlling gas release in the rods during the base irradiation and the transient test. According to FUTURE, fission gas accumulates on the grain boundaries during the base irradiation. The code indicates that variations in the fuel microstructure resulting from the base irradiation cause the level of gas release to vary along the fuel stack in rods AG11-9 and AG11-10 during the transient test. Fission induced bubble re-solution becomes increasingly important for release during the latter stages of the transient test. Moreover, the code calculations imply that bubble migration could have played a significant role in the release process.
Bibliographic Reference: ARTICLE: NUCLEAR ENGINEERING AND DESIGN, VOL. 117 (1989) PP. 211-233
Record Number: 1989128075800 / Last updated on: 1990-11-09
Available languages: en