No abstract

Research and development of innovative oxide fuels doped with minor actinides for use in fast reactors are underway. Management of minor actinides in a fast reactor fuel cycle is a key technology for successful realization of a sustainable energy supply with a low impact on the environment. Americium-doped oxide fuels are focused on as representative of minor actinides-containing fuel. Two types of fuels were designed and fabrication tests were carried out. Fundamental properties were also investigated. Results can effectively be reflected to establishment of the fast reactor cycle with minor actinides.

An in-cell remote fabrication technique was developed for MOX fuel pellets containing 3 and 5% americium (Am-MOX fuel pellet). The fuel pellet was fabricated by means of conventional powder metallurgy. A series of fuel pellet fabrication apparatuses were systematically installed in the alpha-gamma cell (hot cell) to protect workers from a strong -ray exposure from 241 Am, and were remotely controlled from a panel in the operation room outside the hot cells as much as possible. From a preliminary UO 2 pellet fabrication run, ball milling of powder for 4 h, pressing at 4 t/cm 2 and sintering at 1,700 C for 2 h were determined as a good fabrication, but the ball milling time was too short for the UO 2 and Am-PuO 2 powders of different morphologies to be uniformly mixed. Then, the 5% Am-MOX fuel pellet of density more than 93% T.D. which is proper to the irradiation in FBR was successfully fabricated by extending the ball milling time for more than 10 h. It was, furthermore, found that the complete cleanup of the powder feeder was necessary in the transition of fabrication runs to prevent the formation of uranium and plutonium spots in the pellets.