Neutron radiography in the beam of the IBR-30 reactor

The possibility of obtaining images of neutron fields with complex geometrical configuration by means of neutron radiography on the external neutron beam of the IBR-30 reactor is demonstrated. A device for irradiating experimental assemblies of absorbers in the ordinary water is described. The device consists of a cylinder aluminum vessel placed on a table rotating around a vertical axis. The absorber assemblies under study are inserted in the vessel which is filled with water. The assemblies are cut in the planes in which the distribution of the neutron flux is studied, and neutron conversion foils are inserted into the cuts. Because of the neutron conversion foil ''memory'' irradiation of the rotating cylinder in a directed beam is equivalent to irradiation which is isotropic with respect to asimuth. As an example the image of the neutron field of the uranium resonance group is given in a lattice model water uranium reactor. Necessary irradiation times for obtaining a good image of the resonance neutron flux have been about 30-60 min with the reactor power of 15 kW