Status of the design and investigation for hydraulic rabbit irradiation facility

The Oarai Research and Development Center of Japan Atomic Energy Agency has been promoting a remodeling plan of Japan Materials Testing Reactor (JMTR), with a schedule to restart it in FY2012. Since the half-life of ⁹⁹Mo is short at about 66.7 h, the control of irradiation period is required in face of its manufacturing. For this reason, the use of 'hydraulic rabbit irradiation facility', which can perform irradiation and retrieval at an optional time during reactor operation, becomes necessary. The hydraulic rabbit irradiation facilities that are planned for improvement this time is aimed to effectively perform the manufacture of ⁹⁹Mo and radioisotopes as one of the state-of-the-art research infrastructure projects. The plan is that the insertion number of irradiation rabbits into the reactor tube is changed from the conventional maximum three to maximum five, and in addition, external reactor circulation system is remodeled in accordance with the change of the number of irradiation parts. The additional plan is that prior to the fabrication and installation of the equipment, the removal of the existing equipment and the non-destructive test in order to check the soundness of recycled equipment such as buried piping will be performed. (A.O.)