Ultra Low-Dose Radiation: Stress Responses and Impacts Using Rice as a Grass Model

We report molecular changes in leaves of rice plants (Oryza sativa L. - reference crop plant and grass model) exposed to ultra low-dose ionizing radiation, first using contaminated soil from the exclusion zone around Chernobyl reactor site. Results revealed induction of stress-related marker genes (Northern blot) and secondary metabolites (LC-MS/MS) in irradiated leaf segments over appropriate control. Second, employing the same in vitro model system, we replicated results of the first experiment using in-house fabricated sources of ultra low-dose gamma (γ) rays and selected marker genes by RT-PCR. Results suggest the usefulness of the rice model in studying ultra low-dose radiation response/s

High precision analysis of isotopic composition for samples used for nuclear cross-section measurements

For the accuracy improvement of nuclear data of minor actinides and long-lived fission products in the project of “Research and development for Accuracy Improvement of neutron nuclear data on Minor Actinides”, the isotopic compositions of two Am samples (241Am sample and 243Am sample) were analyzed by thermal ionization mass spectrometry. Only the peak of 241Am was observed in the analysis of 241Am sample, and level of isotopic impurities were improved from 0.1% to 0.0004%. In the analysis of 243Am sample, the peak of unreported isotope of 242mAm was observed in addition to the peaks of 243Am and 241Am. The mass spectrometry also showed that 243Am sample has other unreported impurities such as 239Pu and 240Pu

Research and development for accuracy improvement of neutron nuclear data on minor actinides

To improve accuracy of neutron nuclear data on minor actinides, a Japanese nuclear data project entitled “Research and development for Accuracy Improvement of neutron nuclear data on Minor ACtinides (AIMAC)” has been implemented. Several independent measurement techniques were developed for improving measurement precision at J-PARC/MLF/ANNRI and KURRI/LINAC facilities. Effectiveness of combining the independent techniques has been demonstrated for identifying bias effects and improving accuracy, especially in characterization of samples used for nuclear data measurements. Capture cross sections and/or total cross sections have been measured for Am-241, Am-243, Np-237, Tc-99, Gd-155, and Gd-157. Systematic nuclear data evaluation has also been performed by taking into account the identified bias effect. Highlights of the AIMAC project are outlined

Cherenkov counting of 90Sr and 90Y in bark and leaf samples collected around Fukushima Daiichi Nuclear Power Plant

The radioactivity of 90Sr and 137Cs in environmental samples, bark and leaf, collected around the Fukushima Daiichi Nuclear Power Plant in May 2013 was determined with the aim of investigating the migration of both nuclides using their radioactivity ratio. The radioactivity of 90Sr was determined by using Cherenkov counting of 90Y after purification using Sr resin and that of 137Cs was determined by -spectrometry. Quench correction in Cherenkov counting was investigated by measurements of samples spiked with purified 90Y revealed that the radioactivity could be evaluated without quench correction. The radioactivity ratio of 90Sr to 137Cs in bark samples of 4.2×10-3 and 1.2×10-2 was compared with the results from soil samples collected in July 2011 to show that the migration of 90Sr was slower than 137Cs in bark and tree