Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ogawa, Rina; Nakata, Hisakazu; Sugaya, Toshikatsu; Sakai, Akihiro
JAEA-Technology 2022-010, 54 Pages, 2022/07
JAEA-Technology-2022-010.pdf:11.07MB
Japan Atomic Energy Agency has considered trench disposal as one of the disposal methods for radioactive wastes generated from research facilities and other facilities. The trench disposal facility is regulated by "Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors". In particular, the design of the trench facility is regulated by a rule under the law. When the rule was amended in 2019, the design of the trench disposal facility required equipment to reduce ingress of rain water and groundwater. In the report, studies on the design of a trench disposal facility to adapt to the amended rule were performed. The trench disposal facility has considered being established in a place lower than groundwater level. Therefore, it was decided to study covering soil at the upper part of the trench facility, because the ingress water in the facility is mainly derived from rain water. In this study, it was decided to evaluate the design of covering soil of the radioactive waste categorized into chemically stable materials. Therefore, as the examination method, a parameter study on varying the permeability coefficient and thickness of the layers composing cover soil. In the parameter study, the velocity of the water infiltrating into the trench facility was evaluated. Based on the results, more efficient design of the layers composing the covering soil was considered. The result showed that the impermeable efficiency of the covering soil was different depending on the thickness and the permeability conductivity of each layer. As a result, it was possible to understand the impermeable performance of covering soil by the permeability coefficient and thickness of each layer. We will plan to decide the specification of the cover soil while examination of future tasks and cost in the basic design.
Nishida, Nobuho; Ohara, Yoshiyuki; Kawamoto, Tsutomu
Heisei-28-Nendo Zenkoku Kozan, Seirenjo Gemba Tantosha Kaigi Shigen/Shinzozai Koenshu, p.69 - 74, 2016/06
Japan Atomic Energy Agency Ningyo-toge Environmental Engineering Center, has been conducting environmental remediation of the Ningyo-toge mine and Togo mine, after decades of mine-related activities including uranium exploration, mining and test milling were terminated, with doing safety measure, under Mining Safety law. As the one, culvert installation and multi-layered capping were performed at Upstream of Yotsugi Mill Tailings Pond to inspect about stability of multi-layered capping with checking rainwater infiltration restraint and radon dissipation inhibiting effect, from FY 2011 to FY 2012. And it was presumed possibility of amount of underground water is increased, as result of fluctuation numerical analysis for Upstream of Yotsugi Mill Tailings Pond before and after the multi-layered capping, and the water level of bowling holes around the Pond and spring water which flows from lower place of the Pond. But a culvert possesses enough drainage function and groundwater does not rise to the multi-layered capping part. Therefore, it is considered that there isn't problem to the stability of the current state of the multi-layered capping, but we will continue the monitoring of the water level of the bowling hole around the Pond, and the spring water which flows from lower place of the Pond.
Saito, Hiroshi; Sato, Yasushi*; Sakamoto, Atsushi*; Torikai, Kazuyoshi; Fukushima, Shigeru; Sakao, Ryota; Taki, Tomihiro
JAEA-Technology 2015-063, 119 Pages, 2016/03
JAEA-Technology-2015-063.pdf:86.2MB
Ningyo-toge Environmental Engineering Center has been conducting environmental remediation of the Ningyo-toge Uranium Mine, after decades of mine-related activities were terminated. Its purposes are to take measures to ensure safety and radiation protection from the exposure pathways to humans in future, and to prevent the occurrence of mining pollution. As part of the remediation, upstream part of the Yotsugi Mill Tailings Pond, the highest prioritized facility, has been remediated to fiscal year 2012. Multi-layered capping has been constructed using natural material, after specifications and whole procedure being examined in terms of long-term stability, radiation protection, economics, etc. Monitoring has been carried out to confirm the effectiveness of the capping, in terms of settlement, dose and radon exhalation rates, etc. Monitoring of drainage volume of penetrated rainwater is planned. Accumulated data will be examined and used for remediation of downstream part of the Pond.