GAMMA-RAY LEAKAGE THROUGH A SLIT IN LEAD SHIELD. I.

In continuation of a series ot mockup tests for the first Japanese nuclear ship, reactor γ-ray leakage through a double-bend two-dimensiond passage in a leqd slab was experimentally studied. This zig-zag slit channel is recognized to be an effective device against γ-ray leakqge at shield seams. Such leakage may occur through straight passages with normally incident γ-rays, or else with oblique incidence, in the form of streaming.In the case of zig-zag channel, it should be noted that there exist certain incident angles at which the shielding effect is morkedly impaired. The components of penetration calculated by ray-analysis method have been compared with experimental results. The existence of a slit in a lead slab increases scattered γ-rays, which are localized near the shield surface, but which spread widely with increasing distance from wall.