To easily perform a work for drawing in or out a custodial rack for a handling tool to/from custodial positions in a short time by constituting the custodial rack so that it is placed on a slide plate, and it is provided with a rack main body having an arm seat receiving the handling tool and a lock member interposed between the slide plate and the rack main body.

A custodial rack 20 for fuel assembly handling tool is installed on the upper face of the circumferential wall 5 of a used fuel storage pit 3. The upper end part of a handling tool 10 is provided with a hanger 13, and it is hung by the hook of a crane through the hander 13. When the handling tool 10 is not used, the upper end is placed on the arm seat 21 of the custodial rack 20 for custody. In this case, the major part of the handling tool 10 under a rotary bearing 15 is in the shield water 4 of the storage pit 3 to be shielded from radioactive rays. The rack 20 is provided with a rack main body 23 supporting the arm seat 21 and a slide plate 25. The rack main body 23 is moved between a custody position on which the arm seat 21 is overhung over the storage pit 3 and a drawing-in position on which the arm seat 21 is not over the storage pit 3, and it is selectively fixed by a lock member.