Abstract: An alpha survey radiac employing a photomultiplier tube and scintillation detector has been developed. The instrument utilizes transistor circuitry and operates from two standard flashlight batteries. Four linear ranges are provided with full scale indication on the highest range corresponding to 10,000 g /m2 Pu2 39. The instrument was designed with .a separable probe and a telescoping extension for easier ground monitoring. A thorium metal source is attached to the instrument housing for checking instrument calibration in the field. The device conforms satisfactorily to the military requirements for altitude, humidity, vibration, shock, and storage. The operational battery life is in excess of 40 hours. Instrument error at low temperatures slightly exceeds the 20% accuracy requirement; however, adequate measurements are readily made by using the thorium check source to provide a check point. Instrument response to low energy X-rays is excessive. However, tests indicate that a simple lead filter will eliminate this difficulty.
Abstract: The theoretical response of a low-geometry scintillation counter to any photon-emitting nuclide whose decay scheme is known is developed. It is used to compute the counting rate, as a function of time, of (1) individual and total fission products resulting from. 10^4 simultaneous slow-neutron fissions of U^235 and (2) several other nuclides for 10 initial atoms. The calculations extend from ~45 min to 301 days after fission.
From abstract: The effect of heat on the surface removal of concrete was studied by conducting brush tests on samples which had been subjected to prolonged high temperatures in an oven or in direct contact with an oxy-propane flame. Other methods of heat-treating surface layers of concrete were investigated by direct application of an oxy-aluminum torch on the surface and by the exothermic chemical reactions of pyrotechnic compositions placed directly on the surface.
From introduction: The principal work described below is the development and tests of a slow neutron flux generator based on a generator developed at the University of California (UCRL 8359, W. Patterson, Roger Wallace, "A Method of Calibrating Slow Neutron Detectors"). It is shown that a tolerance flux density of slow neutrons results within a cubical cavity 15 inches on an edge with 4-inch-thick walls of water or paraffin wax when a plutonium-beryllium source emitting about 7 million neutrons per second is placed within the cavity according to a standard procedure. The principle on which the generator is based is that the fast neutrons from the source are slowed to near thermal velocities by scattering from the cavity walls. (Although the principal interest is in the slow flux, a primary fast flux is present at any point depending on the inverse square of the distance from the source.) The variation of slow neutron flux density over the walls of the cavity is unimportant for the calibration of thermal neutron detectors which follow a 1/v or 1/E response law (where v and E are the neutron velocity and energy), so that the detector is sensitive mainly to the slow neutron flux. As stated, the method provides a slow neutron flux density (instead of the neutron density only) so that a calibration for detectors placed within the cavity can be given either in terms of flux density of slow neutrons or, by simple conversion, in terms of dose-rate.