Final Report of the FUJI Project Concerning the Research and Development of Advanced Sphere-Pac Fuel among JNC, PSI and NRG

Morihira, Masayuki ; Nakamura, Masahiro  ; Ozawa, Takayuki   ; Kihara, Yoshiyuki; Hellwig, C.*; Ingold, F.*; Bakker, K.*

The collaboration project concerning sphere-pac fuel (SPF) among JNC, PSI and NRG was performed from 1996 till 2005. Total sixteen fuel segments (eight pins) of three types of fuel were fabricated in PSI. Two SPF segments contained 5%Np in addition to 20%Pu-MOX. Other segments contained no Np. The fuel microsphere for SPF was fabricated by the internal gelation process. The trial to apply the internal gelation process to Np-MOX fabrication was successfully attained. The test pins were transported to Petten in the Netherlands in September 2003 and assembling of the sample holders was done. Three steady state irradiation tests and one power-to-melt test were performed in HFR. Two test pins (four segments) were irradiated every tests simultaneously. The former tests were performed mainly to obtain the restructuring data of SPF in the early beginning of irradiation. The later was done to evaluate PTM linear heat rate of SPF with the reference data for pellet fuel. The irradiation tests were performed in January to March 2004 and December 2004 to March 2005. Post irradiation examination was completed in August 2005. In this project the irradiation tests in HFR was doubtless main task but so many other works were also performed i.e. transfer of the technology concerning modeling and design of sphere-pac fuel from PSI to JNC, additional destructive PIE of IFA-550.11 fuel (a power ramp test of sphere-pac fuel segment irradiated in the Gösgen PWR), fabrication tests in PSI, etc. This report summarized the planning of the irradiation tests, fuel design, result of fabrication, irradiation, post irradiation examination and data analysis. SPF design codes, DIRAD-S, SIMPLE-S which was developed by implanting SPF models of PSI into the pellet design codes in JNC, were verified with the irradiation test data in this project to show good accuracy.