The purpose of this study is to develop a quick method for estimation of 131I concentrations in the air using data measured by monitoring posts. In this method, 131I concentrations were estimated by multiplying 131I count rates at the full-energy peak measured with NaI (Tl) detector by concentration conversion factor. The concentration conversion factor for monitoring posts in JAEA oarai center was calculated with EGS5 monte carlo code. As a result, concentration conversion factor for infinite-air-source was 25.7 Bq/m3/cps.
In 2011, the released radioactive materials including tritium (T) from damaged reactors at Fukushima Dai-ichi nuclear power plant has caused much environmental problems. After the Fukushima Dai-ichi Nuclear Power Plant Accident, the specific activity of T in precipitation was increased in Niigata city. In this study, each monthly precipitation (imitative ground infiltrated precipitation) was collected at the rooftop of Niigata University. Such a sample was subsequently enriched by electrolytic enrichment method (SPE method), and the specific activity of T of each enriched sample was measured by low-background liquid scintillation counter. In addition, the relation between specific activity of T and nssCa2+ (i.e., non-sea-salt Ca2+) concentration in monthly precipitation was also discussed. Moreover, the concentrations of cations, i.e., Na+, K+, Ca2+, and Mg2+, in monthly precipitation and the specific activity of T in spring water at top of Mt. Zao (and other mountains in Fukushima prefecture) were also measured. Based on the above-mentioned matters, it was found that the influence of the Fukushima Dai-ichi Nuclear Power Plant Accident on environment in Niigata city almost disappeared after four months from the accident.
Brown rice of non-glutinous paddy rice (Oriza sativa) was used to investigate radiocaesium translocation to grains by selecting hulled rice and unsuitable rice grains for food. It was assumed that hulled rice was not mature enough to remove hulls compared to mature rice so that hulled rice was classified as immature rice. The unsuitable rice grains were such as colored or not proper shape ones, thus it was though that they were disturbed their filling process and thus their nutritional condition was not in the same level as the normally grown mature grains. The weight of immature rice grains had about 95％ of normal-weight grains and thus it was indeed slightly immature but the 137Cs concentration was almost the same as that of the normal mature grains. On the other hand, unsuitable grains were low in 137Cs concentration by 14％, suggesting that translocation of radiocesium was affected from early stage of filling process. Probably the decrease would occur especially if germs and/or aleurone layer were damaged.
Complicated magnetic structure like the helical one, which is realized in systems with competing spin interaction, often induces ferroelectric order. This phenomenon is called multiferroic, and has changed a concept that magnetic and ferroelectric orders rarely coexist. Moreover, the discovery of multiferroic systems has presented a possibility of controlling electric polarization by magnetic field and magnetization by electric field. In this article, after a description of characteristics and origins of the multiferroic phenomenon, dynamics of the spin system are introduced.