Measurement and analysis of JOYO MK-II spent MOX fuel decay heat(2)

Maeda, Shigetaka   ; Nose, Shoichi; not registered; Aoyama, Takafumi 

Decay heat of the spent MOX fuel is important not only from the viewpoint of reactor safety concerning a decay heat removal at the reactor shut down, but also for the thermal design of the spent fuel storage and handling facility. In order to obtain the experimental data and to improve the accuracy of calculation, the decay heat of spent fuel subassemblies of the JOYO Mk-II core was measured. The burn-up was 66 GWd/t and the cooling time was between 40 and 150 days. Measured decay heat of the spent fuel subassemblies was approximately 1446 2466320W. The decay heat was calculated by "ORIGEN2" code and then it was compared with the measured value. In the "ORIGEN2" calculation, the JENDL-3.2 cross section library and the JNDC-V2 decay data library were used and fuel power calculated by the core management code system "MAGI" was used as a input. The ratios between calculated and experimental values, C/Es, were approximately between 0.94 and 0.90. The discrepancy between calculation and measurement was considered to be larger than the experimental error (1 = 1.73.0%) or the uncertainty of calculated FP decay heat (12%). It appears due to the uncertainty of actinides decay heat and that indicates cross sections of actinides and initial composition of actinides are important to evaluate decay heat accurately.