Measurements of the photoneutron yield in the irradiation of heavy materials in closed shells

The high-energy beams of bremsstrahlung from electron accelerators are deemed suitable for the inspection of the technological parameters in the production of fissionable materials when placed behind a shielding shell. An all-wave counter was used to examine the dependence of the integral photoneutron yield in the irradiation of 238U and 235U. Position of the accelerator, objects for examination, registration device, and a block diagram of the measuring circuit are given. The all-wave counter is described and the optimizations of directivity and other problem-solving selections are detailed. The neutron yield from a hollow steel shell is determined. The results obtained for the detection direction along the normal to the axis of the probing beam show that the dependence on the thickness of the shell is linear and very small. Analysis shows that uranium isotopes can be identified at a shielding wall thickness greater than 10 mm. General results indicate that the photoneutron method can be used for the inspection of uranium isotopes behind a shielding shell