Procedure for determining the direction and position of oriented holes in a reactor pit

Fitted rods are partly inserted into oriented holes in the reactor pit, and fitted tubes are slid onto their protruding ends; in the tubes, at least one recess is made for the rod handling. The free tube ends are fixed, e.g. with a solidifying material. The mutual linking of the tubes so formed is leant by means of struts on the bottom or walls of the reactor pit. In this manner, the position of the slid-on tubes with respect to the reactor pit is fixed. The fitted rods are slid out, and the remaining complex of mutually fixed tubes with struts is taken out of the reactor pit. The position of the mutually fixed tubes and struts determines the direction and position of oriented holes in the reactor pit. Entering the pit is then unnecessary, so that the hazard of personnel irradiation is eliminated. The complex of fixed tubes and struts can be directly employed in the new reactor vessel, which obviates the necessity to tediously adjust the tubes in the reactor vessel and pit. (M.D.). 1 fig