Using the numerical values in the provisions of the law, the proportion evaluated in the safe side was examined. At the time, the following were examined, whether there is no superfluous protection or underestimation in comparison with NCRP and the Law. The transmission rate using in the 1/10 value layer were higher than that calculated in the half value layer in both lead and concrete. For the leakage in X-ray examination room, the effective doses were estimated to be less than the limit of the controlled area of 1.3m Sv/3 months. However, the dose using the law are 3.3 times in maximum in comparison with the NCRP. In the case of QI (Quality Index) =0.5, it was found that the dose were overestimated in 3.6 times in maximum.
Radionuclides contained in three kinds of misch metal products and two kinds of ingots were analyzed using a Ge (Li) semiconductor detector. Lanthanum-138 (138La) and several daughter nuclides derived from thorium and uranium series were detected in all samples.All misch metal products and ingots were determined to be radioactive consumer products (RCP), although they have not been regarded as RCP in Japan. 138La showed the highest nuclide content rate of all the radionuclides, and the lanthanum metal ingots displayed the highest specific activity at 720m Bq·g-1. The maximum external effective dose was estimated to be 3.7m Sv when a metal match was carried for 8, 760 hours at 1mm from the skin. The calculated effective dose under some conditions exceeded 10μ, Sv per year.This value corresponded to the exemption standard proposed by the UK's National Radiological Protection Board.Individuals working with large amounts of RCP should be appropriately protected.
Electric field strength distribution around the digital cellular telephone (cell phone) transmitting 1.5GHz band was analyzed by using an isotropic probe. Five types of electronic pocket dosimeters (EPDs) were exposed to the fields for 50sec under four kinds of configurations relative to the cell phone. The field distribution expanded around the antenna and had a maximum strength level of 36.5±0.3V/m.The cell phone caused abnormally high values (wrong dosages) to four EPDs out of five due to electromagnetic interference.Three out of the four EPDs exceeded the upper limits of dose range depending on the configurations, and the maximum value of wrong dosage among the EPDs was 1, 283μSv. The minimum distance preventing electromagnetic interference (protection distance) differed with each EPD and ranged from 2.0cm to 21.0cm. The electromagnetic immunity levels of EPD-1, 2, 3, 4 and 5 were 13.3, ≤35, ≤32, 9.2 and≤35 V/m, respectively. Although the immunity levels were either equal to or greater than the IEC-standard level, those of the EPDs should be enhanced greater than the IEC-standard from the standpoint of radiation protection.