²²²Rn concentration in groundwater was investigated around the southwestern foot of Mt. Fuji. The results showed that ²²²Rn concentrations in water samples of the coastal area were higher than those of the inland area and its distribution seemed not to be correlated with the distribution of fault in the study area. In addition, most of the water samples with high ²²²Rn concentration showed relatively high strontium isotope ratio (⁸⁷Sr/⁸⁶Sr) indicating the influence of sand and gravel layer in alluvial fan. Consequently, the main factor for the increase of ²²²Rn concentration in groundwater at the coastal area was estimated the radioactive decay from ²²⁶Ra which is concentrated in the alluvial fan deposit.

It is important for the processing manufacturers of the uranium fuels to determine the quantity of U-235 and the enrichment. This study shows that the U-235 content evaluated from measurement of 186 keV γ rays emitted from U-235 can be corrected by a shielding factor, X_geometry which quantified uneven distribution of U-238. The X_geometry is evaluated from the direct and the scattered γ rays from the 1001 keV emitted from the Pa-234 m. The X_geometry was originally introduced for U-238 measurements. Because U-235 coexists with U-238, the X_geometry is also possible to apply to the U-235 measurements. The experimental study with simulated waste drums demonstrated that the quantification errors of the U-235 content and the enrichment are reduced considering the factor.

Large amounts of high-activity-level contaminated water were generated from the nuclear accident of Fukushima Dai-ichi Nuclear Power Plant caused by the Great East Japan Earthquake. At present, the cold shutdown is completed by cooling system, while large amounts of contaminated (>500,000 m³) are still stored. This paper deals with the selective decontamination properties of Cs⁺ and Sr²⁺ by using inorganic adsorbents: zeolites, insoluble ferrocyanides, crystalline silicotitanates, and potassium titanates. Zeolites have three important abilities; (1) high selectivity for Cs⁺ and Sr²⁺, (2) Cs gas trapping ability, and (3) self-sintering ability. As for multi-nuclides adsorbability, mordenite, chabazite, ferrierite and clinoptilolite group have strong adsorbability for Cs⁺, and A-type and X-type zeolites for Sr²⁺ in seawater. Other zeolites, such as L-type zeolite and Ag⁺ adsorbed zeolites (A-type and X-type zeolites), have high decontamination abilities for actinoids and radioactive I⁻ions, respectively. Stable ceramic solidification of secondary solid wastes can be accomplished by using the above trapping and sintering abilities; mixing and sintering with zeolites are effective for the stable Cs immobilization and lowering of Cs leachability.

High-transition-temperature superconductivity in cuprate oxide emerges by carrier-doping into Mott insulator, which has the spins with the quantum spin number of 1/2 and the strong superexchange interaction with the coupling constant of ～1500 K. Therefore, the study of spin dynamics in the cuprate superconductor by the neutron scattering technique is one of the most difficult and challenging research issues. However, an operation of new intense neutron sources and a recent development of instrumental techniques enable us to study the excitation spectrum in a wide energy-momentum space. As the results, we revealed the existence of hierarchical structure in the magnetic excitation of superconducting compounds. In this paper, we overview the features of the hierarchical magnetic excitation in cuprate superconductor and discuss the possible origin of the hierarchy on the basis of the results of the precise measurements carried out at the J-PARC/MLF.

J-PARC Materials & Life Science Facility (MLF) has state-of-the-art neutron instruments. In this report, we explain the character of the neutron source of MLF, which is a short pulsed neutron source, and the time-of-flight method, which can most effectively extract the performance of the source. Also we show the cutting edge technique for the inelastic neutron scattering by implementing “multi incidence energy method” and “pulse shaping chopper method,” including some examples of measurements. Those techniques were realized for the first time at MLF, and the instruments are now achieving the world leading performance.