We have proposed a new theory on gamma assay for 238U determination of uranium-contaminated waste drums. According to this theory, regardless of the inhomogeneity of waste matrix density or uranium source distribution, we can accurately determine the amount of 238U contained in drums nondestructively using count rates of gamma rays of two energies(1001keV and 766keV) emitted from 238U progeny nuclide 234mPa. In this paper, we have verified the theory by tests under various waste conditions made by simulated waste drums. We have estimated the relative error to be less than 20%, and the detection limit to be 1.2Bq/g when the specific activity of uranium is 25000Bq/g, in these cases. We have confirmed that this new assay system is efficient for the rational classification of uranium wastes to be disposed of.
In the case of the metropolitan area, radioactive substances came flying from March 15 to 16 and from March 20 to 23. We measured the radioactive substance contained in leaves using a HPGermanium semiconductor detector. As a result of the measurement, we confirmed the following. (a)The main radioactive substance are 132Te, 131I, 134Cs, and 137Cs. (b)The 134Cs and the 137Cs were almost same quantity. (c)Radioactive concentration such as tea leaf etc. has decreased by the physical half life and the weather condition etc.
To clarify the mechanism of radiocaesium contamination of rice, we performed an imaging analysis to find the radiocaesium distribution pattern throughout the rice plant. The result demonstrated that the rice plant which was grown on the particular paddy field, where a highly contaminated brown rice was produced in 2011, contained larger amount of radiocaesium in the newer leaves than in the older leaves. In contrast, rice plant grown in an another area, where the contamination level in grain was low, contained larger amount of radiocaesium in the older leaves. It was suggested that the uptake of radiocaesium was promoted and/or radiocaesium in plant was redistributed to the newer organs during summer season when the rice was heading.
Radioactivities of several tissues of Pacific cod, nibe croaker, and white croaker captured around Fukushima were estimated with an imaging plate system. There were relatively high radioactivities in muscle. Effects of washing on residual Cs radioactivities in fish meat were estimated. Three-times washing with 0.1% NaCl solution was effective for the removal of radiocaesium from contaminated fish meat. Homogenization of meat was also effective for the removal of radiocaesium.
Neutrinos stand out among elementary particles with their unique nature, yet had been left in obscurity for a long time. Now, researchers are spending enormous efforts to uncover the secret of neutrinos. In this review, attributes of neutrinos and weak interaction are explained. The significance of neutrino study, detectors and historical perspectives are also mentioned.
The basics of the Mössbauer Effect and the latest application research fields were introduced. The principle and measuring system of Mössbauer Effect, and the parameters from Mössbauer spectra were summarized. The feature of monochromatic beam of synchrotron orbital radiation for nuclear forward scattering and nuclear inelastic scattering was compared with that of γ ray from Mössbauer radioisotopes. Furthermore, the in-beam Mössbauer spectrometry with accelerator also was introduced, and the recent research area were touched through international conferences of Mössbauer Effect.