Postirradiation examination of "JOYO" MK-II core fuel subassembly (Fab.No.PFD010); Nondestructive testing on subassembly and its fuel elements

not registered; not registered; not registered

Postirradiation Examination (PIE) of "JOYO" MK-II core fuel sub-assembly (Fab.No.PFD010) has been performed. This subassembly was the first one which subjected to PIE in Fuel monitoring Facility (FMF). The purposes of the PIE were to confirm the safty performance of the subassembly in reactor "JOYO" at 100 MW reactor power, and to get the basic data on the irradiation behavior of MK-II core fuel subassembly and its fuel elements in the early stage of 100MW power operation. The average burnup of the subassembly is estimated to 4600 MWD/MTM. The results of the present examination can be summarized below (1)There was no pin failure and/or damages in the subassembly, and the subassembly and its fuel elements have behaved normally in reactor. (2)The observation on fuel pin and wire surfaces indicated a slight "contact mark". The size of the mark were very small both in width and in length. They seem to be different from those of wear mark observed on MK-I fuel pins. (3)It was confirmed that there was no significant irradiation behavior in the subassembly and its fuel elements.