Evaluation of fuel pin internal pressure by the 7 spectrum measurement

Katsuyama, Kozo ; Fujishima, Tadatsune ; Nagamine, Tsuyoshi; Matsumoto, Shinichiro

85Kr, which is one of gaseous nuclides generated in nuclear fissions, can be detected by gamma spectrum measurement. It is possible to calculate the fission gas amount discharged into the gas plenum of fuel pin and the inner pressure, based on the measurement data. In this study, the measurement and calculation were applied to the fuel pins irradiated in the experimental fast reactor JOY0. Then puncture testing was carried out for the applied fuel pins to measure fission gas amount and real inner pressure. As a result, it was confirmed that that calculated data were appropriate in general, compared with those gained by puncture testing. (1)The error of inner pressure calculated on the basis of gamma spectrum measurement is less than 25%, compared with the puncture test results. (2)As the result of this method applied to the fuels irradiation test rig (No.PFB090), the highest pressure was calculated in one of fuel pins loaded into N0.5 compartment, which burn-up was over 110 GWd/t. The pressure was about 50 Kg/cm2. This value was sufficiently less than that used in the fuel design.