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2024.05.07
Dr. Tatsuhiko Sato, Dr. Yosuke Iwamoto, Dr. Shintaro Hashimoto, Dr. Takuya Furuta, and Dr. Tatsuhiko Ogawa were awarded the Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology (MEXT) in the field of science and technology for their “Development of a general-purpose radiation transport simulation code PHITS”. PHITS is currently used by approximately 10,000 researchers and engineers in 76 countries, contributing to the radiation-related research and industry all over the world. Please visit PHITS website (https://phits.jaea.go.jp) in more detail about the code.
2024.05.07
Drs. Yosuke Iwamoto et al. of Research Group for Radiation Transport Analysis received the Prize of “JNST Most Cited Article Award 2023” for the paper entitled, “Benchmark study of the recent version of the PHITS code” (J. Nucl. Sci. Technol., Vol. 54, 617-635 (2017)) on the 27th of March 2024.
A general-purpose radiation transport simulation code PHITS is a Monte Carlo simulation code developed under collaboration between JAEA, Research Organization for Information Science and Technology (RIST), High Energy Accelerator Research Organization (KEK) and other institutes. The code can transport nearly all types of radiation in any material using the implemented nuclear reaction models and the nuclear data libraries. Then, it can be applied to various fields such as design of radiation facilities, medical physics calculations, radiation protection studies, space radiation research, and other studies involving radiation transport simulations.
To validate the accuracy of the PHITS code for various applications, we carried out comprehensive benchmarks including particle production cross sections in the nuclear reactions, neutron transport calculations, as well as photon and electron scattering reactions. Agreements were found to be sufficiently satisfactory for most experimental data. However, some discrepancies were also observed between the simulations and the experimental data; particularly in particle production with incident particle energies below 100 MeV, and in neutron production from lithium targets bombarded by protons. This study has provided us important information that can guide further improvements for PHITS.
All of the benchmark results are available online for the public, and have been widely used by PHITS users all over the world as a reference of PHITS reliability in their applications.
To Download: https://www.tandfonline.com/doi/full/10.1080/00223131.2017.1297742
2024.05.07
Dr. Hiroaki Terada, Dr. Katsunori Tsuduki, and Dr. Masanao Kadowaki of Research Group for Environmental Science and Dr. Haruyasu Nagai of Nuclear Science and Engineering Center received the prize of “56th Atomic Energy Society of Japan Award: Distinguished Technical Award” for Atmospheric-dispersion database system WSPEEDI-DB on March 27, 2024.
In response to the Fukushima Daiichi Nuclear Power Plant accident, JAEA has been working on the estimation of the source term and clarification of the atmospheric dispersion processes of the radioactive materials discharged into the atmosphere due to the accident using the Worldwide version of System for Prediction of Environmental Emergency Dose Information version 2 (WSPEEDI-II). However, it was difficult to compare calculation results for various conditions because the detailed and complex WSPEEDI-II calculation model required considerable calculation time. To address this issue, we have developed a new atmospheric dispersion database system (WSPEEDI-DB) by making calculations quicker and renovating the interface for easy implementation of calculations and analysis.
The newly developed calculation method enables the automatic execution of dispersion calculations for a specific release point and the creation of a database of calculation outputs (dispersion-calculation DB) in advance, making it possible to immediately obtain prediction results for specified release conditions. In addition, we have extended the functions based on this calculation method: a method for estimating source term that is difficult to obtain in an emergency by statistical analysis comparing the dispersion-calculation DB and various environmental monitoring data, and a method for evaluating the uncertainty of future prediction results that is difficult with previous methods by applicating machine learning using the past long-term dispersion-calculation DB as training data.
The previous applications of this system are as follows. We applied it to the assessment of the monitoring posts deployment around the Shimane nuclear power station and demonstrated that this system can contribute to improving the effectiveness of disaster prevention planning. For the Fukushima Daiichi nuclear power station accident, we optimized the source term using various environmental measurements and reconstructed the spatiotemporal distribution of radionuclides in the environment, thereby contributing to the refinement of the dose assessment by the Ministry of the Environment, Japan and United Nation’s Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). In addition, as a response to overseas events, a dedicated automatic calculation system for underground nuclear tests by North Korea is in operation as a system of the Nuclear Regulation Agency.
Please see the website for more details about WSPEEDI-DB.
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