Development of producing MOX fuel by "Short Process", 1; Development of Pu/U ratio control by liquid mixing: An annual report in fiscal 2000

not registered; Kawabe, Akihiro; not registered ; not registered

In plutonium conversion development facility (abbreviated to PCDF) in JNC (Japan Nuclear Cycle Development Institute) Tokai Reprocessing Plant, investigations of producing MOX nuclear fuel by a simplified process have been studied. A study of this process, which is called "Short Process", has been carried out for the purpose of decreasing the production cost of MOX fuel in cooperation with plutonium fuel center in JNC Tokai Works. The purposes for this study are, (1)to decrease the number of equipment by the simplification of our MOX fuel production process (2)to improve the working ratio (3)to stabilize the quality of MOX fuel (4)to decrease the amount of the hold-up of MOX fuel in glove boxes (5)to improve an efficiency of transporting nuclear materials (6)to decrease operating cost In this "short process", it is necessary to mix plutonium nitrate solution and uranium nitrate solution with relatively high accuracy on the assumption that the adjustment of Pu/U ratio is controlled as a liquid state. As a result, the volume of these nitrate solutions has to be measured and transported to another vessel within high accuracy. At first, in fiscal 1999, a mock-up apparatus equipped with airlift systems, which imitated solution-mixing process in PCDF, was designed, made and assembled together. In fiscal 2000, by using this mock-up airlift apparatus, tansferring experiments were carried out both to estimate the accuracy of Pu/U mixing ratio in PCDF operation plant and to confirm characteristics of the airlift pump systems in PCDR The results showed that Pu/U ratio control in PCDF plant could not always satisfy the specifications for MOX fuel. From both the operation data in PCDF and results of our experiments, investigations were carried out for the purpose of improving the accuracy of Pu/U ratio control.Our mock-up airlift apparatus was modified and the accuracy of Pu/U ratio control was reexamined. It was confirmed that Pu/U ratio control by modified airlift ...