— This project concerns with the detection efficiency of the portable Triple-to-Double Coincidence Ratio (TDCR) at the National Institute of Metrology of Ionizing Radiation (INMRI-ENEA) which allows direct activity measurement and radionuclide standardization for pure-beta emitter or pure electron capture radionuclides. The dependency of the simulated detection efficiency of the TDCR, by using Monte Carlo simulation Geant4 code, on the Birks factor (kB) and defocusing parameter has been examined especially for low energy beta-emitter radionuclides such as 3 H and 14 C, for which this dependency is relevant. The results achieved in this analysis can be used for selecting the best kB factor and the defocusing parameter for computing theoretical TDCR parameter value. The theoretical results were compared with the available ones, measured by the ENEA TDCR portable detector, for some pure-beta emitter radionuclides. This analysis allowed to improve the knowledge of the characteristics of the ENEA TDCR detector that can be used as a traveling instrument for in-situ measurements with particular benefits in many applications in the field of nuclear medicine and in the nuclear energy industry.
Abstract—To understand the risk for dry storage concrete casks in the cask loading, transfer, and storage phase, the purpose of this research is to establish the probabilistic risk assessment (PRA) analysis methodology for dry storage concrete casks by using SAPHIRE 8 code. This analysis methodology is used to perform the study of Taiwan nuclear power plants (NPPs) dry storage system. The process of research has three steps. First, the data of the concrete casks and Taiwan NPPs are collected. Second, the PRA analysis methodology is developed by using SAPHIRE 8. Third, the PRA analysis is performed by using this methodology. According to the analysis results, the maximum risk is the multipurpose canister (MPC) drop case.
This paper describes evaluation results of thermophysical properties of stainless steel (SS) containing 5 mass % boron carbide (B4C) in its solid phase. First, the authors synthesized SS-B4C samples with emphasis on 5 mass % B4C and SS using a hot press method and then evaluated its homogeneity in several ways, such as chemical composition analysis, metallographic structure observation, and micro X-ray diffraction. This study also evaluated the density and the specific heat and thermal conductivity of the SS-B4C sample and found that the density becomes lower and the temperature dependence of the density decreased as the temperature rose compared to that of stainless steel Type 316L (SS316L) used as a reactor material. The specific heat became slightly higher than that of SS316L and showed similar temperature dependence up to 1073 K. Unexpectedly, the thermal conductivity became lower than that of SS316L and showed similar temperature dependence up to 1273 K.
One of the leading obstacles in scaling down semiconductor lasers in all three dimensions is the diffraction limit. Experimental results show that plasmonic cavities can overcome this great challenge. However, one of the main problems is how to utilize these structures more efficiently as integrated devices in optoelectronic and plasmonic circuits since they have low coupling efficiency. One solution is to benefit metal-insulator-semiconductor (MIS) nanostructures with inline or waveguide-integrated nanocavities to achieve higher coupling efficiency. In this paper, a plasmonic nanolaser based on semiconductor-insulator-metalinsulator-semiconductor (SIMIS) nanostructure is proposed and investigated. This structure is suitable for utilizing as a waveguideintegrated nanocavity in a hybrid plasmonic waveguide based on coupled nanorods. Simulation results based on the finite element method (FEM) show that the presented structure with a radius of 40 nm and insulator layer thickness of more than 8.7 nm has lower threshold and simultaneously lower normalized mode area at the lasing wavelength of 490 nm compared to the previously reported MIS nanostructure with the same parameters. So, the SIMIS based spaser may result in a proper performance as a waveguideintegrated plasmon source.
