Apparatus for the neutron-radiography testing of a boiling water reactor control element

摘要

A boiling water reactor has a control element disposed in a water pond. An apparatus for the neutron-radiography testing of the control element includes a film cassette having a recording area. A water- free hood is fitted over the control element. The hood has an open bottom and a wall facing the film cassette. The wall has an opening formed therein with a cross section corresponding to the recording area. A holding device fits over the opening for receiving the film cassette. The holding device has a downwardly open side extended below the opening through which the film cassette is to be introduced into the water-free space in the holding device. A neutron source, a collimator and the film cassette lie in one measurement plane. The opening in the hood wall reduces the proportion of scattered neutrons and the impairment of image quality caused by a film of water remaining between the hood wall and the film cassette and by the hood wall itself, in prior art devices in which the film cassette is disposed outside the hood.