A simple personnel neutron dosimeter based on albedo principle was investigated. This dosimeter was designed to respond to the albedo neutrons and then the neutron dose was determined. The albedo dosimeter consists of a pair of TLD-600 and TLD-700 dosimeters from which the separate dose fraction of neutrons and gamma-rays can be evaluated. A capsule made of phenol resin with boron carbide was used as the shielding material, and the reading ratio of outer and inner TLD was used to determine the energy correction factor. Phantom irradiation was performed in the Am-Be, Pu-Be neutron fields, and the monoenergetic fast neutrons from the Van de Graaff accelerator as well. A Monte Carlo computer code was developed to simulate the experimental condition. In this study the albedo neutron dosimeter system proposed can be used for routine personnel monitoring, and the neutron dose-equivalent measured is within an overall error of ±40%.
The transfer of tritium from a mouse injected with tritiated water to a mouse contact with the injected mouse was observed. Tritium transfered mainly through the air of small cage where both mice were haused. The kinetics of transfer to the tissues exposed to air, the skin and the lens, were similar to those to the tissues unexposed to air, the muscle and the testes. The absorbed doses of contact mice were 3-8% of injected mice for 125hr. The results showed that the contaminated individual was the source of contamination himself.
New calibration method of thermoluminescent dosimeter (TLD) reader was developed at Power reactor and nuclear fuel development corporation, Tokai Works. Calibration data and characteristics of TLD readers were examined to establish the new calibration method. It was found that it was practically effective to check two items at the calibration of TLD reader. The first item was coefficient of variation of TL measured value concerning the elements irradiated by external standard source and the second item was difference between mean measured value and irradiated dose. It was practically convenient to maintain ±5% and ±4% respectively at the calibration. The TLD readers could be controled sufficiently on routine basis, if the readers were calibrated by this method once a month.