The tritium concentration in initial groundwater(i.e., freshly infiltrating rainwater) is necessary for groundwater dating. We collected simulated infiltrating water as the initial groundwater and examined its characteristics for tritium concentration. First, in Tokyo, the tritium concentration of simulated infiltrating water was compared with that of rainwater, atmospheric moisture, groundwater, spring water, and sap water. While rainwater, atmospheric moisture, and simulated infiltrating water remarkably changed month-to-month or with every rainfall event, groundwater and spring water were nearly constant throughout the year. Second, we collected the simulated infiltrating water monthly at four sampling sites widely dispersed across Japan(i.e., Sapporo, Niigata, Tokyo, and Matsuyama) from 2004 to 2010. Sapporo and Niigata showed high tritium concentrations as compared with the relatively low concentrations in Tokyo and Matsuyama. These results indicate that we can obtain annual maximum and minimum concentrations at each site, and that we can estimate the tritium concentration in initial groundwater at each site by using a mixing model composed of these maximum and minimum concentrations.
To make dried-fruits of persimmon(Diospyros kaki), its fresh fruits were generally processed to decrease their water-contents to about 30 - 50%. During this food process, their radiocaesium concentrations increased without any loss, and, occasionally, the dried-fruits may exceed the food standard level of 100Bq/kg(edible form). Thus, it is necessary to estimate the radiocaesium concentrations in the products before the fresh fruit harvesting and processing. For this purpose, radiocaesium concentrations in leaves of persimmon trees were monitored with time. The 137Cs concentrations in the fruits were usually lower than those in the leaves and the concentration ratio was less than 0.4 on a fresh weight basis. The ratio became smaller when closer the harvest season. Thus the concentration of leaves could be a good indicator to estimate the processed persimmon fruits.
This is a report of the project of MEXT(The Ministry of Education, Culture, Sports, Science and Technology)to support high school students researching radiation etc. This subject research consists of an exchange meeting, independence research, and a presentation meeting of the results. Media introduced the project and this was a very reputable project. However, regrettably this support project was broken off in the business year of 2012. In this document, the outline of the support project for seven years is introduced and the possibility of future deployment is discussed.
In-beam Mössbauer spectroscopy(IBMS) involves online measurement of Mössbauer γ-radiation emitted from excited atoms produced by radioisotope(RI) implantation and nuclear reactions. It provides us useful information on local atomic and electronic configurations, site distributions, dynamic diffusion processes, and unusual chemical states of isolated Fe atoms during the lifetime of the excited Mössbauer state. In this paper, the features and several application studies of the in-beam Mössbauer spectroscopy using a short-lived 57Mn(T1/2＝85s) are mainly mentioned.
We examined the protective efficacy of Japanese sake against ionizing X-irradiation and biologically analysed sake for radioprotective compounds. The sake used in this experiment is Junmai-shu (ethanol content, 10.5%) that made only from rice and malted rice. Male C57BL/6JJms mice aged 9 weeks were orally administered 0.6mL sake/mouse within 30min of 7.8Gy whole body irradiation or 0.2mL sake daily for one week prior to and after irradiation control mice received either Futsu‐shu(ethanol content, 15%), pure ethanol(10.5%) or saline. Futsu-shu is made from rice and malted rice with alcohol added. To test the effect of X-ray-induced lethality in mice, we observed short-term survival(30days) rates in the mice after exposure. Mice administered Junmai-shu demonstrated significantly increased survival rate compared with saline(p‹0.01). The survival rates were greatest for the Junmai-shu group followed by the Futsu-shu, ethanol and saline groups. Radioprotection was not solely a result of hydroxyl radical scavenging by ethanol because pure ethanol demonstrated lower protective effect than sake. Sake contains a greater variety and quantity of amino acids than most other alcoholic drinks. Junmai-shu had a much higher amino acid content than Futsu-shu(1771mg/L vs. 932mg/L), suggesting one possible source of radioprotection. Our results reveal that pure ethanol was slightly protective against lethality but to a lesser degree than sake. A high content of amino acids in sake is one of the unique features of sake that provides a radioprotective effect.
Vanadate glass is semiconductive with the electrical conductivity(σ) of 10−7 - 10−5 S cm−1, which is caused by 3d electron(polaron) hopping from VVI(or VIII) to VV. Interestingly, a drastic increase of σ from 10−5 to 100 S cm−1 was observed when 20BaO·70V2O5·10Fe2O3 glass was isothermally annealed at around crystallization peak temperature(Tc) of 500°C, a quadrupole splitting(Δ) decreasing from 0.70 to 0.54mm s−1. These results indicate that the increase in was in proportion to the decrease in the local distortion of FeO4 tetrahedra as reflected in of the Mössbauer spectra. Based on the newly obtained results, the vanadate glass is expected to be a promising candidate as a cathode material of secondary battery. It is concluded that Mössbauer spectrometry is one of the essential techniques for the characterization of functional glasses and ceramics.