In its latest basic recommendations issued in 2007, the International Commission on Radiological Protection (ICRP) recommends that the working conditions of a pregnant worker, after declaration of pregnancy, be such as to ensure that the additional dose to the embryo and fetus would not exceed about 1 mSv during the remainder of the pregnancy, where exposures of the embryo and fetus of pregnant workers are considered and regulated as public exposures. However, it remains unclear, e.g.,  whether such recommended additional dose of about 1 mSv to the embryo and fetus is the whole body equivalent dose or the effective dose,  if the latter, how to compute the effective dose while the currently recommended tissue weighting factors (wT) do not include the stochastic risks of in utero exposures and while the unavailability of the current epidemiological data sets does not allow computation of detriment for in utero exposures, and  whether the embryo and fetus are the public. This paper briefly reviews historical changes in ICRP recommendations on protection of pregnant workers, embryo and fetus, and then discusses pertinent issues behind the 2007 recommendations.
At the JAEA MOX fuel facilities, workers engaged in glove box operations uses two personal dosemeters, one worn on the trunk under a protective apron and the other at the collar over the apron. The recorded lens of the eye dose is based on the photon dose measured by the collar dosemeter plus the neutron dose measured by the under-apron dosemeter. To estimate preliminarily the potential impact of the ICRP-proposed eye dose limit which reduced down to 20 mSv per year on the current plant operation, we carried out an investigation of the dose records for the workers over last 11 years. Of a total of 2,843 workers' records analyzed, no worker's annual eye dose exceeded the proposed limit of 20 mSv; about 0.9 % was greater than 15 mSv, with a maximum of 18.9 mSv. This result suggests that keeping the eye dose under 20 mSv per year would be achievable without an extremely major impact on plant operation; but the fact that the effective dose is certain to be limited by the eye dose likely to be closer to the relevant dose limit will result in more stringent administrative control on the eye dose and might require, if necessary, additional shield and a protective eyewear for some workers.
This study investigated the interaction with water masses from the distribution of Iodine-129, Cesium-134, and Cesium-137 in the eastern area off Cape Shiriya, Aomori prefecture. Iodine-129, Cesium-134, and Cesium-137 concentrations in water samples collected in July 2012 were 13.7-30.2 nBq/L, N.D.-5.45 mBq/L, and 0.79-9.44 mBq/L, respectively. Concentrations of these radionuclides at the 25.5-26.7 isopycnal (σt) increased above the environmental levels before the Fukushima Daiichi nuclear accident, and their increase depended on a formation process of water masses. It is considered that concentrations at the 25.9-26.0 σt were increased by mixing the Tsugaru Warm Current Water System with near-surface water in the Oyashio region, but concentrations at the 26.4 σt were increased by mixing the Tsugaru Warm Current Water System with the Kuroshio-Oyashio mixed water.
The purpose of this study is to identify the significance of the change in the intestinal absorption rate values the (ƒ1 value) to the change of ingestion dose coefficient following an acute intake of 134Cs and 137Cs. This study also attempted to provide a simple calculation method of ingestion dose coefficients given a specific value of ƒ1 and age groups by using linear regression models. In the range of 0-1, 10 different values of ƒ1 for 1-year, 5-year-old, and the adult group were chosen and used in a separate calculation by using, a biokinetic compartment model, DCAL. It was found that the lower values of ƒ1 lead to a significant decrease of the committed effective dose coefficient for an adult. Oppositely for children, the decrease of the coefficient was not as significant. This study also suggests that the significance of dose coefficient change due to the variation of ƒ1 substantially depends on the biological half-life of the radionuclide, the fraction of absorbed energy and the mass of organs and tissues in human body.
The problem of uncertainty as a general consequence of incomplete information and the approach to quantify uncertainty in metrology is addressed. Then, the statistical foundation of the concepts of uncertainty in measurements is discussed. The basics of the ISO Guide to the Expression of Uncertainty in Measurement as well as of characteristic limits according to ISO 11929 are described and, finally, the role of measurement uncertainties in the assessment of conformity to requirements is dealt with in detail.
Tellurium (Te) isotopes were released into the environment with radioactive cesium (Cs) and radioactive iodine as a result of the accident at the Fukushima Daiichi Nuclear Power Plant. Te-127m and Te-129m, with half-lives of 109 and 33.6 days, may have moved from soil to foodstuffs and been ingested by local residents. Data on the transfer of Te to plants through roots are essential to estimate the contribution of radioactive Te to the internal radiation dose to the public in the early stages of the accident. However, little is known about soil retention and transfer from soil to plant of Te in the environment. In the present study, the transfer factors from soils to radish and komatsuna were determined for stable Te and Cs. These two kinds of plants were cultured in four kinds of soils adjusted to 1 mg Te or Cs /dry-soil-kg. After 2 weeks-2 months of cultivation, Te and Cs in plants were measured by ICP-MS. The experimental data showed that exchangeable cation retarded the transfer of Cs, and anionic adsorbent of the soils decreased the transfer of Te. The transfer factors of Te were 8.6 × 10-3-3.2 × 10-2 from soil to leaves of radish, 1.2 × 10-2-3.0 × 10-2 to roots of radish, and 1.4 × 10-2-5.1 × 10-2 to leaves of komatsuna. Those of Cs are 2.3 × 10-2-7.6 × 10-1, 1.1 × 10-2-2.7 × 10-1 and 6.7 × 10-3-3.9 × 10-1, respectively.