Irradiation test of fuel containing minor actinides in the experimental fast reactor JOYO

Soga, Tomonori ; Sekine, Takashi ; Wootan, D. W.; Tanaka, Kosuke  ; Kitamura, Ryoichi; Aoyama, Takafumi 

The MA-containing mixed oxide fuel irradiation program is being conducted using the experimental fast reactor Joyo of the JAEA. Two irradiation tests were conducted in the JOYO MK-III 3rd operational cycle. Six prepared fuel pins included MOX fuel containing Am (Am-MOX) or MOX fuel containing Am and Np (Np/Am-MOX). The first test was conducted with high linear heat rates of approximately 430 W/cm maintained during only 10 minutes in order to confirm whether or not fuel melting occurred. After 10 minutes irradiation in May 2006, an Am-MOX pin and a Np/Am-MOX pin in the test subassembly were replaced with dummy pins. Remaining four fuel pins were re-irradiated in Joyo for 24-hours in August 2006 to obtain MA re-distribution data. Linear heat rates for each pin were calculated using MCNP and then adjusted using reaction rates of neutron dosimeter measured in the MK-III core. Post irradiation examination of these pins to confirm the fuel melting and the re-distribution are underway.