MEASUREMENTS OF RADIATION INTENSITIES IN VERTICAL CONCRETE-LINED HOLES AND AN ADJOINING TUNNEL AT THE TOWER SHIELDING FACILITY

Abstract

Fast neutron and gamma-dose rates within 4-ft-dia., 20-ft-deep, concrete- lined holes were measured at the Tower Shielding Facility. The radiation source was the Tower Shielding Reactor II (TSR-II) enclosed in a shield that modified the neutron to gamma ratio of the reactor leakage spectrum to more closely resemble that of a weapon spectrum. The holes were located at horizontal distances of 100, 228, and 450 ft from the reactor. From the hole at 100 ft extended a reinforced concrete-lined tunnel, 6 ft high, 21/2 ft wide, and 20 ft long, with its ceiling 10 ft below ground level. The experimental measurements consisted of vertical traverses in the three holes and horizontal traverses in the tunnel. The parameters varied included distance from the reactor, the angle of elevation of the reactor with respect to the horizontal at the hole, and the material and thickness of the shield over the hole. Reactor elevation angles ranged from 15 to 90 deg . The shields over the holes were concrete, iron, and laminated iron and concrete slabs. (auth