Historical changes and Correspondence to Research and Test Reactors New Regulatory Standards for Monitoring Post in Oarai Research and Development Institute, JAEA

Hamaguchi, Takumi; Yamada, Junya; Komatsuzaki, Naoya*; Hatakeyama, Takumi; Seya, Natsumi; Muto, Yasunobu; Miyauchi, Hideaki; Hashimoto, Makoto

JAEA-Technology 2022-038, 65 Pages, 2023/03

JAEA-Technology-2022-038.pdf:4.3MB

New regulatory requirements were developed taking into account the lessons-learnt from the accident at Fukushima Daiichi Nuclear Power Station on March 2011. The new regulatory standards required that monitoring posts should be diversified in transmission systems and equipped with backup power supply equipment for design basis accidents. In this report, we look back on the history of monitoring posts in Oarai Research and Development Institute, explained the application for the permission of reactor installment license, application for approval of the design and construction method, pre-use operator's inspection and improvement design of monitoring posts. This report also includes about inspection based on act on special measures concerning nuclear emergency preparedness and the installation of KURAMA-II, which was carried out in conjunction with the improvement of monitoring post for new regulatory standards. As an appendix, application document for approval of the design and construction method are included.

Improvement of estimation of I concentrations in the air using data measured by monitoring posts applied by determination of passing-through time of plume using noble gas counts

Yamada, Junya; Hashimoto, Makoto; Seya, Natsumi; Haba, Risa; Muto, Yasunobu; Shimizu, Takehiko; Takasaki, Koji; Yokoyama, Sumi*; Shimo, Michikuni*

Hoken Butsuri, 52(1), p.5 - 12, 2017/03

https://doi.org/10.5453/jhps.52.5

The purpose of this study is to improve a quick method for estimation of I concentrations in the air using data measured by monitoring posts in case that a nuclear disaster occurs. In this method, I concentrations were estimated by multiplying I count rates of cloud-shine measured with NaI (Tl) detector by concentration conversion factor. A previous study suggested that it was difficult to determine passing-through time of plume from temporal change of I count rates or dose rate. Our study applies the method for estimating passing-through time of plume from temporal change of noble gas counts. The I concentrations in the air at Oarai center, Japan Atomic Energy Agency resulting from the accident at the Fukushima Daiichi Nuclear Power Plant were estimated by proposal technique. The result of comparison of this method with sampling method for I concentrations in the air were within factor 3.

None

PNC TJ1545 93-002, 89 Pages, 1993/03

PNC-TJ1545-93-002.pdf:3.03MB

None

Studies on the Field Monitoring Network with -ray Detectors for the Reactor Accident

JAERI 1193, 32 Pages, 1971/03

JAERI-1193.pdf:2.09MB

no abstracts in English

Comparison of I-131 concentrations in atmosphere estimated from pulse-height distribution observed by NaI(Tl) detector at monitoring posts and evaluated from air sampling

Yamada, Junya; Seya, Natsumi; Haba, Risa; Muto, Yasunobu; Hashimoto, Makoto; Shimizu, Takehiko; Takasaki, Koji; Yokoyama, Sumi*; Shimo, Michikuni*

no journal, , 

no abstracts in English

Influence of artificial radionuclide deposited on a monitoring post on measured value of ambient dose rate

Hiraoka, Hirokazu; Hokama, Tomonori; Munakata, Masahiro

no journal, , 

Neighboring inhabitants of nuclear facilities must evacuate according to an ambient dose rate at a nuclear accident. The evacuation is judged by the measured value by monitoring posts (MPs). However, if the measured value increase by artificial radionuclide deposited to MP, it is considered that the dose rate of the surrounding environment is overestimated. The purpose of this research is to evaluate exactly the dose rate even if the radionuclide deposit to the MP, in order to adequately evacuate inhabitants. Just a MP and horizontal ground was simulated. To calculate ambient dose rates from the roof surface of MP and ground surface, Monte Carlo calculation was done. And, it was obtained that the ratio which the dose rate from the roof account for sum of two these dose rates. According to the result, the ratio was 44%. It suggested that the radionuclide could increase the measured value. However, because simulated system was simple, it is considered that the ratio was overestimated.