Irradiation tests for the development of FBR in Joyo

Maeda, Yukimoto; Ito, Chikara   ; Soga, Tomonori 

The experimental fast reactor Joyo is the first sodium cooled fast reactor in Japan. Irradiation tests in Joyo were commenced from 1983 after the completion of core conversion work from the MK-I breeder core to the MK-II irradiation test bed core. Many valuable irradiation tests were carried out to develop fuels and materials for the prototype fast reactor Monju and a demonstration fast reactor. After the 35 duty cycles operation by the MK-II core, Joyo was upgraded to the high performance MK-III core to increase irradiation capability in 2003. Unique irradiation tests for the FaCT project such as MA bearing MOX fuel and ODS ferritic steel were carried out in the MK-III core. In light of the shutdown of several fast reactors around the world, the ability to make such major contributions to reactor development takes on even greater significance. Irradiation tests in Joyo contribute to the FaCT project, and also to promote the international cooperation such as Generation-IV.