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JAEA Reports

Improvement of intragranular fission gas behavior model for fuel performance code FEMAXI-8

Udagawa, Yutaka; Tasaki, Yudai

JAEA-Data/Code 2021-007, 56 Pages, 2021/07

JAEA-Data-Code-2021-007.pdf:5.05MB

Japan Atomic Energy Agency (JAEA) has released FEMAXI-8 in 2019 as the latest version of the fuel performance code FEMAXI, which has been developed to analyze thermal and mechanical behaviors of a single fuel rod in mainly normal operation conditions and anticipated transient conditions. This report summarizes a newly developed model to analyze intragranular fission gas behaviors considering size distribution of gas bubbles and their dynamics. While the intragranular fission gas behavior models implemented in the previous FEMAXI versions have supported only treating single bubble size for a given fuel element, the new model supports multiple gas groups according to their size and treats their dynamic behaviors, making the code more versatile. The model was first implemented as a general module that takes arbitrary number of bubble groups and spatial mesh division for a given fuel grain system. An interface module to connect the model to FEMAXI-8 was then developed so that it works as a 2 bubble groups model, which is the minimum configuration of the multi-grouped model to be operated with FEMAXI-8 at the minimum calculation cost. FEMAXI-8 with the new intragranular model was subjected to a systematic validation calculation against 144 irradiation test cases and recommended values for model parameters were determined so that the code makes reasonable predictions in terms of fuel center temperature, fission gas release, etc. under steady-state and power ramp conditions.

Journal Articles

Development of a chemical transport model coupled with a mesoscale meteorological model and application to atmospheric diffusion of volcanic gases from the Miyake Island

Nishizawa, Masato*; Chino, Masamichi

Taiki Kankyo Gakkai-Shi, 39(1), p.31 - 42, 2004/01

http://ci.nii.ac.jp/naid/110003841053

no abstracts in English

Journal Articles

Real time observation of initial thermal oxidation using O $_{2}$ gas on Si(0 0 1) surface by means of synchrotron radiation Si-2p photoemission spectroscopy

Yoshigoe, Akitaka; Moritani, Kosuke; Teraoka, Yuden

Applied Surface Science, 216(1-4), p.388 - 394, 2003/06

https://doi.org/10.1016/S0169-4332(03)00451-3

Times Cited Count：9 Percentile：45.93(Chemistry, Physical)

It is well known that the initial Si(0 0 1) oxidation by O $_{2}$ gas is an important reaction system because it is usually used to form gate-oxide films on MOSFET. With decreasing the size of ULSI, it is necessary to control the surface reaction with atomic scales. In this study, we report observation of thermal oxidation using O $_{2}$ gas on Si(0 0 1) surface by means of synchrotron radiation photoemission spectroscopy at the soft x-ray beamline, BL23SU, in the SPring-8. We clarified the chemisorption processes of O $_{2}$ on Si(0 0 1) surface over 773K regions at the initial oxidation stages from the results of Si2p core-level shifts. The fundamental understanding of surface reaction is expected to contribute the development of the future nanotechnology.

Journal Articles

Real-time simulation and analysis on long-range atmospheric dispersions of volcanic gases discharged from the Miyake Island

Furuno, Akiko; Nagai, Haruyasu; Umeyama, Nobuaki; Chino, Masamichi

Taiki Kankyo Gakkai-Shi, 37(1), p.23 - 34, 2002/01

http://ci.nii.ac.jp/naid/110003840994

The active volcano Oyama in the Miyake Island has been emitting a huge amount of volcanic gases since the first eruption in July 2000. High concentrations of SO2 gas originated in Oyama frequently appear in the wide area from the northeast to the west part of Honshu, Japan. This paper describes real-time prediction of SO2 dispersion covering the Tokai and Kanto District and its verification by comparing with SO2 observation data from October to November 2000. Atmospheric dispersions of SO2 are calculated by using our software system that combines a regional atmospheric dynamic model and a particle random walk model. It was proved that the real-time prediction of our system has adequate precision. The importance of including the effect of wet deposition was also shown. The release amounts estimated from the comparison between the calculation result and the monitoring data are 20,000 - 50,000 ton/day, which is consistent to measured ones at the Miyake Island.

JAEA Reports

Atmospheric dispersion simulations of volcanic gas from Miyake Island by SPEEDI

Nagai, Haruyasu; Furuno, Akiko; Terada, Hiroaki; Umeyama, Nobuaki; Yamazawa, Hiromi; Chino, Masamichi

JAERI-Research 2001-012, 28 Pages, 2001/03

JAERI-Research-2001-012.pdf:1.77MB

Japan Atomic Energy Research Institute is advancing the study for prediction of material circulation in the environment to cope with environmental pollution, based on SPEEDI (System for Prediction of Environmental Emergency Dose Information) and WSPEEDI (Worldwide version of SPEEDI), which are originally developed aiming at real-time prediction of atmospheric dispersion of radioactive substances accidentally released from nuclear facility. As a part of this study, dispersion simulation of volcanic gas erupted from Miyake Island is put into practice. After the stench incident at the west Kanto District on 28 August 2000 caused by volcanic gas from Miyake Island, simulations dealing with atmospheric dispersion of volcanic gas from Miyake Island have been carried out. This report describes the details of these studies.

Journal Articles