Fabrication of BaI2-ZrH2-x composite for I-129 transmutation target

Transmutation of radioactive iodine (I-129) is one of effective methods to reduce environmental burden and disposal risk of radioactive wastes, and then, will reduce public exposure to less than one-tenth of the simulated value. From our previous studies on transmutation of I-129 by fast reactors, it has been clarified that a composite of barium iodide (BaI2) and zirconium hydride (ZrH2-x) had high efficient transmutation rate because of minimizing self-shield for thermal neutrons. It was found that homogeneously mixed composite of 10 vol% of BaI2 and 90 vol% of ZrH2-x were good target form and that it could achieve about 10% per year of transmutation rate. However, the mixed powder of low BaI2 and high ZrH2-x composition is hard to be sintered, because ZrH2-x has higher melting point than BaI2. ZrH2-x powder particles can not be connected each other at lower temperature than the melting point of BaI2. Therefore, a new target form was designed as the pellet of ZrH2-x dispersed BaI2-ZrH2-x composite; sintered BaI2-ZrH2-x composites insert in the dispersed holes of ZrH2-x body. It was clarified that the ZrH2-x pellet dispersed BaI2-ZrH2-x had high transmutation performance equal to the BaI2-ZrH2-x sintered pellet by analysis. (author)