For decontamination in Fukushima evacuated areas, a considerable number of low-cost, efficient radiation detectors such as survey meters will be needed in the coming years. We developed a polyethylene naphthalate based scintillator (®SCINTIREX) recently. It is a plastic scintillator that emits sufficient fluorescent light upon exposure to radiation without the need for wavelength shifting, thus reducing costs of the survey meters. We tested the performance using the OKEN survey meter with a 1mm thick polyethylene naphthalate sheet, and found that the count rate for a 36Cl source and a 60Co source can be more than doubled when the plastic surface is modified to allow more light to reach the photo detector.
Removal/adsorption of 32PO43− from the water by the naturally occurring ancient shellfish fossil(ASF) was examined. As a result, selective adsorption ability of ASF for 32PO43− was revealed. Then, the ASF containing soap was prepared, and its usefulness as decontamination agent was investigated, using various 32PO43− contaminated plates consisting of different materials. The ASF containing soap had a remarkable decontamination effect on lead plate, aluminum plates, and the floor material in radioisotope facility, which were generally hard to be decontaminated. Besides, though 20 - 40% of pollution remained in latex gloves, human hand skin, and stainless steel(SUS) plate by the twice washing with the water, the contaminations were decontaminated with the ASF containing soap by more than 90%, suggesting the usefulness of ASF as the decontamination agent for the contamination with radioactive phosphate ion.
Individual external exposure doses of 8 persons living at the south area in Saitama Prefecture were measured by electronic pocket dosimeter. The values of 8persons' doses ranged from 1.43 to 1.88 μSv/day. There was about 30% difference in 8 persons' doses. Converting into annual external exposure dose, they were in the renge of 0.52-0.69 mSv/year, which were similar to or slightly lower than the external exposure dose by natural radiation in Japan(0.63mSv/year). After the accident at Fukushima Daiichi Nuclear Power Plant, annual external exposure dose increased 0.069mSv/year at most. It was about 7% of the annual effective dose limit for member of the public(1mSv/year).
Recent developments in methods of testing for biobased carbon content as related to biomass-based chemicals and plastics are reviewed. Examples of biomass-based products are introduced, together with the details of certification systems for biomass-based products that are in place worldwide. 14C concentration measurements have been used to calculate biobased carbon content in products. In this paper, we introduce a number of techniques such as accelerator mass spectrometry(AMS), liquid scintillation counting(LSC), and β-ionization(BI) that are used to calculate the 14C concentration to determine biobased carbon content. The regulations governing these methods, and the sample pretreatment processes, are based on the international standards ASTM D6866-12, CEN/TS 16137, and ISO/CD 16620. It was found that AMS could measure many liquid and solid chemicals, and plastic and polymer composites, and that it is sufficiently accurate to conform for the determination of biobased content using some pretreatment methods. Furthermore, some measurement methods of the biobased carbon content and the biobased synthetic polymer(plastic) content of a number of samples are shown.
Among various radiation exposure sources, natural radiation and medical exposure are two main radiation sources to Japanese population. Interesting difference between western countries and Japan are smaller radiation dose by 222Rn inhalation and greater radiation dose by 210Po intake in Japanese population. Large amount of intake of 210Po is due to intake of marine foods by Japanese population.
The recent developments of “nanotechnologies” and “spintronics” are boosting up the demands to experimentally elucidate the local electronic structures, including magnetism, of thin films and nanostructures. Mössbauer spectrometry is a powerful experimental tool for the investigations on local electronic and vibrational properties of solids. In this article, Mössbauer spectroscopic studies using 119Sn nuclei on nanoscale thin films, especially on Heusler alloy films, are outlined topically as an example of applications of Mössbauer spectrometry to the studies on magnetism of thin films.