共查询到4条相似文献,搜索用时 15 毫秒
1.
Shigekazu Hirao Hiromi Yamazawa Takuya Nagae 《Journal of Nuclear Science and Technology》2013,50(2):139-147
The atmospheric release rates of I-131 and Cs-137 from the Fukushima Daiichi nuclear power plant in March 2011 were estimated by comparing environmental monitoring data of air concentration and deposition rate on a regional scale with calculated values from an atmospheric dispersion model. Although the release rates were not estimated for all days after 11 March, because of lack of monitoring data, temporal changes in the release rates were reasonably estimated with estimated uncertainties in a factor of 3.3 and 2.9 for I-131 and Cs-137, respectively. A large release was estimated from the night of 14 March to at least the afternoon of 15 March, with maximum values of 7.2 × 1015 Bq h?1 for I-131 and 1.5 × 1014 Bq h?1 for Cs-137. The release rates during other periods were estimated at one- to two-orders of magnitude smaller than the largest release rate on 15 March. Uncertainty in the estimated release rate for 15 and 20 March was larger than for other periods. The significant release during 14 and 15 March and the trend of the release rate by the end of March were consistent with previous reports. This agreement, despite using different datasets, shows robustness of the temporal changes estimated in the studies. 相似文献
2.
Jun Ishikawa Kenji Kawaguchi Yu Maruyama 《Journal of Nuclear Science and Technology》2013,50(3):308-314
The accident at unit 3 of the Fukushima Dai-ichi nuclear power plant was analyzed with THALES2 for the progression of severe accident coupled with Kiche for the iodine chemistry in aqueous phase. The analysis indicated that, compared with the analysis without the aqueous phase iodine chemistry, a significantly larger amount of iodine was released from the water pool of the suppression chamber (S/C) with forms of molecular iodine and organic iodine due to the repeated operation of the containment venting system. It was also implied in the sensitivity analysis that the late phase release of the volatile iodine species was largely influenced by the pH of the S/C water and gas–liquid mass transfer coefficient under a gas–liquid two-phase flow condition. 相似文献
3.
Osamu Kurihara Katsuta Kanai Takahiro Nakagawa Chie Takada Norio Tsujimura Takumaro Momose 《Journal of Nuclear Science and Technology》2013,50(2):122-129
The Great East Japan Earthquake Disaster on 11 March 2011 caused an unprecedented accident at the Fukushima Daiichi nuclear power station operated by Tokyo Electric Power Company (TEPCO). Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency performed internal dose measurements of 560 employees involved in the accident during the period from 20 April to 5 August in 2011 at the request of TEPCO. The present paper describes our measurements of 131I in the thyroid that is the predominant contributor to the internal dose. These measurements were carried out using an HPGe detector installed in a low-background shielded chamber made of 20-cm-thick steel and the detector was placed adjacent to the subject's neck. The typical minimum detectable activity of this technique was 10 Bq for a counting time of 10 min; however, this sensitivity made it difficult to identify a residual thyroid content of 131I corresponding to a committed effective dose of 20 mSv for late subjects. This paper discussed technical issues experienced through the measurements such as the influence of 131I in the rest of the body, the calibration phantom of use, and so on. 相似文献
4.
To investigate what happened in reality during the Fukushima Daiichi Nuclear Power Plant accident, the phenomena within reactor pressure vessel and the discussion of ties with the environmental monitoring measurement are very important. However, the previous study that treats phenomena of the both has not necessarily advanced up to the present time. The source terms predicted by simulation codes such as MELCOR has not yet been consistent with the reverse estimation by WSPEEDI code using environmental measurement data. This study investigated 131I and 137Cs release behaviors during the late phase of the accident to contribute to such examination using the 131I/137Cs ratio of the new source terms predicted by Katata. The 131I release by the gas–liquid partition from the contaminated water in the 1F2 and 1F3 reactor buildings which was pointed out in the previous study was reevaluated using the new source terms. In addition, paying attention to the similarity of the core conditions between the Fukushima accident and the Phébus FPT3 experiment using the B4C control rods, the release of organic iodine (CH3I) during the 1F3 suppression pool venting, formation of CsBO2 and its release behavior were examined which have not yet been sufficiently studied so far. 相似文献