Investigation of the fuel temperature evaluation method at BOL

Ishii, Tetsuya; not registered; not registered

It is one of the major subjects in the improvement of the design method for determining the thermal conditions of the solid type Mixed - Oxide (MOX) fuels in FBR to evaluate the fuel temperature at BOL as precisely as possible. Therefore, we have planned to modify the fuel temperature evaluation method "FEVER", which was developed by JNC in 1988, as one of the investigation for the establishment of the precise fuel temperature evaluation method. And, we also have planned to use the modified FEVER, named "FEVER-M", for estimation of the irradiation conditions of the PTM test in Joyo, called "B10 test", planning to perform in 2000. In this work, the following results were obtained; (1)As a result of the modification, the uncertainty in the fuel temperature evaluation of "FEVER-M" is reduced to about 60K. (2)Estimating the irradiation conditions of "B10" test using the method "FEVER-M", it is found that the appropriate maximum linear heat rate for the test is 620 W/cm. The detail plan of the "B10" test were also determined based on the results. (3)Based on the results of this work, it is found that one of the effective procedure for the impovement of the accuracy of the fuel temperature evaluation method seems to calculate the fuel temperature taking the pellet relocation phenomena into account. In future, although there are a lot of matters to be discussed in this phenomena, the design method for the thermal conditions of the MOX fuels in FBR should be performed with taking the pellet relocation phenomena into account.