[en] Purpose: To prevent radioactive contamination of the reactor water and simplify the operation of transferring the spent local power range monitor to a pool and preparation of the space for storing the monitor in the pool by arranging it such that the monitor is cut in the reactor water and that its cut end is closed in the reactor water. Constitution: A device for clamping a spent local power range monitor disposed within the reactor core and for cutting the monitor such that the content will not be exposed are supported by support means such that they are spaced apart in the vertical direction, and the support means is suspended in the reactor water such that it is movable relative to the monitor. Thus, there is no need to mount the cutter in any separately provided support means, and there is no possibility of exposure of the content since the cut end of the monitor is closed by the outer frame. It is therefore possible to prevent contamination of the reactor water. (Horiuchi, T.)