Data of long term hydro-pressure monitoring on Mizunami Underground Research Laboratory Project for fiscal year 2017-2019

Onoe, Hironori; Takeuchi, Ryuji

JAEA-Data/Code 2020-010, 112 Pages, 2020/10

JAEA-Data-Code-2020-010.pdf:6.22MB
JAEA-Data-Code-2020-010-appendix1(DVD-ROM).zip:169.12MB
JAEA-Data-Code-2020-010-appendix2(DVD-ROM).zip:338.45MB
JAEA-Data-Code-2020-010-appendix3(DVD-ROM).zip:448.05MB

The Mizunami Underground Research Laboratory (MIU) Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III), the project is being carried out under the Phase III. The main goals of the MIU Project from Phase I to Phase III are: to establish techniques for investigation, analysis and assessment of the deep geological environment, and to develop a base of engineering for deep underground application. One of the Phase III goals is to construct geological environment models and grasp deep geological changes when expanding the research gallery by research and investigations using research galleries. The long term hydro-pressure monitoring has been continued to achieve the Phase III goals. Furthermore, these monitoring were ceased at the end of FY2019 due to the completion of the MIU project. This report describes the results of the long term hydro-pressure monitoring from April 2017 to March 2020.

Method for groundwater monitoring on the disposal of radioactive waste

Murakami, Hiroaki; Iwatsuki, Teruki; Takeuchi, Ryuji; Nishiyama, Nariaki*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(1), p.22 - 33, 2020/06

https://doi.org/10.3327/jnuce.27.1_22

Geological disposal of radioactive waste requires the large amounts of fundamental technical knowledge throughout the project. Monitoring is carried out to collect site-relevant information for the creation of an environmental database, to assist in the decision-making process, etc. We summarized the current technical level and problems of the groundwater monitoring in the world. Through the research and technology development so far, the technologies have been developed for drilling borehole in the geological environment survey prior to monitoring and the selection of the monitoring site. However, the following technical developments are remaining issues: long-term operation method of monitoring equipment, retrieving method of monitoring equipment after long-term operation, transport method of backfill material for borehole sealing, technical basis for the sealing performance when the borehole-protective casing and strainer tube are left.

Study of groundwater sampling casing for monitoring device

Okihara, Mistunobu*; Yahagi, Ryoji*; Iwatsuki, Teruki; Takeuchi, Ryuji; Murakami, Hiroaki

JAEA-Technology 2019-021, 77 Pages, 2020/03

JAEA-Technology-2019-021.pdf:5.33MB

One of the major subjects of the ongoing geoscientific research program, the Mizunami Underground Research Laboratory (MIU) Project in the Tono area, central Japan, is accumulation of knowledge on monitoring techniques of the geological environment. In this report, the conceptual design of the monitoring system for groundwater pressure and water chemistry was carried out. The currently installed and used system in research galleries at various depths was re-designed to make it possible to collect groundwater and observe the water pressure on the ground.

Background radiation monitoring using manned helicopter for application of technique of nuclear emergency response in the fiscal year 2018 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Komiya, Tomokazu; Iwai, Takeyuki*; Seguchi, Eisaku*; Matsunaga, Yuki*; Kawabata, Tomoki*; Haginoya, Masashi*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.

JAEA-Technology 2019-017, 95 Pages, 2019/11

JAEA-Technology-2019-017.pdf:12.09MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the FDNPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We have carried out the background radiation monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in the aerial monitoring around FDNPS against nuclear emergency response. The results of monitoring around Shimane and Hamaoka Nuclear Power Stations in the fiscal 2018 were summarized in this report. In addition, technical issues were described.

Rapid determination of Sr-90 in environmental matrices by SPE-ICP-MS for emergency monitoring

Fujiwara, Kenso; Yanagisawa, Kayo*; Iijima, Kazuki

Environmental Radiochemical Analysis VI, p.89 - 96, 2019/09

Since Strontium-90 (Sr-90) is one of the high yield and hazardous fission products, accurate and low-level detection of Sr-90 is essential for environmental samples. Especially, in case of nuclear power plant accidents, rapid and precise assessment of Sr-90 for environmental monitoring and health physics is required. In order to evaluate the migration of radionuclides in the environment, not only Sr-90 in water but also those in soil and biological samples should be measured. A new method for rapid quantification of Sr-90 by online solid phase extraction coupled with inductively coupled plasma mass spectrometry (SPE-ICP-MS) has been developed. In this method, it is unavoidable to eliminate the interference by polyatomic ion (e.g., ArCa, Ca) induced by isotopes and matrices in fishes and soil. In this study, SPE-ICP-MS method was applied to the measurement of Sr-90 in fishes, and the influence of the Sr isotopes and coexisting ions such as Ca was evaluated.

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

Hiraoka, Hirokazu; Hokama, Tomonori; Munakata, Masahiro

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 5 Pages, 2019/05

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 42%. It suggested that the radionuclide could increase the measured value. However, because simulated system was simple, it is considered that the ratio was overestimated.

Data of long term hydro-pressure monitoring on Tono Regional Hydrogeological Study Project for fiscal year 2015-2016

Keya, Hiromichi; Takeuchi, Ryuji; Iwatsuki, Teruki

JAEA-Data/Code 2018-020, 58 Pages, 2019/03

JAEA-Data-Code-2018-020.pdf:3.19MB
JAEA-Data-Code-2018-020-appendix1(CD-ROM).zip:203.36MB
JAEA-Data-Code-2018-020-appendix2(CD-ROM).zip:168.01MB

A wide range of geoscientific research aims to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock. The Regional Hydrogeological Study (RHS) project is a one of the geoscientific research program at Tono Geoscience Center. This project started since April 1992 and main investigations were finished to March 2004. Since 2005, hydrogeological and hydrochemical monitoring have been continued using the existing monitoring system. This report describes the results of the long term hydro-pressure monitoring from April 2015 to March 2017.

Evaluation of a surface collection efficiency and a stability of flow rate for the commercially available filters used for ambient radioactive aerosols

Tamakuma, Yuki*; Yamada, Ryohei; Iwaoka, Kazuki*; Hosoda, Masahiro*; Tokonami, Shinji*

Hoken Butsuri (Internet), 54(1), p.5 - 12, 2019/03

https://doi.org/10.5453/jhps.54.5

Airborne radioactivity measurements are necessary to know the contamination level and internal doses for residents after a nuclear accident. In addition, measurements of radon progenies in air, which are the risk factor of lung cancer, are also important to evaluate lung dose. In these measurements, a filter sampling is used to collect radioactive aerosols. However, it is well known that results of the measurement using a filter are strongly dependent on characteristics of the used filter. Selection of a suitable filter is important to achieve the high-resolution and long-term measurement. "Surface collection efficiency (SCE)" and "stability of air flow rate" were examined for six types of filter that are commercially available in Japan. In Japan, cellulose-glass fiber filter paper (HE-40T) is used for an environmental monitoring in Japan. In this study, it was found that the SCE of HE-40T was lower than that of mixed cellulose ester type membrane filter by Merck Millipore (DAWP02500). Attenuation ratio of flow rate for DAWP02500 was evaluated to be 2.9% which was lowest in six filters. The results suggest that the DAWP02500 is the most suitable for collecting radioactive aerosols for a long term.

Background radiation monitoring using manned helicopter for establishment of technique of nuclear emergency response in the fiscal year 2017 (Contract research)

Futemma, Akira; Sanada, Yukihisa; Iwai, Takeyuki*; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.

JAEA-Technology 2018-016, 98 Pages, 2019/02

JAEA-Technology-2018-016.pdf:18.64MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We have carried out the background monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in Fukushima against nuclear emergency response. The results of monitoring around Tomari, Kashiwazaki-Kariwa and Genkai Nuclear Power Station in the fiscal 2017 were summarized in this report. In addition, technical issues were described.

Estimation on the change of the condition of the impervious plug during groundwater recovery experiment

Matsui, Hiroya; Mikake, Shinichiro; Ikeda, Koki; Tsutsue, Jiyun

Dai-46-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.286 - 291, 2019/01

Japan Nuclear Energy Agency (JAEA) has been conducting the groundwater recovery experiment to develop a methodology to estimate the geological environment recovery after closure of the drift at GL-500m in Mizunami Underground Research Laboratory, Japan. For the experiment, an impervious concrete plug was constructed to maintain a recovered water pressure and its functions were assessed based on the monitoring results and interpretation of several kinds of measurements performed inside and outside of the plug during groundwater recovery test. This report summarized the change of the condition of the plug due to groundwater recovery estimated based on the different kinds of monitoring data.