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Nagayasu, Takaaki; Taki, Tomihiro; Fukushima, Shigeru
JAEA-Technology 2016-031, 53 Pages, 2017/02
JAEA-Technology-2016-031.pdf:4.42MB
The forerunner of JAEA, found a smelter in 1964 to do industrialization tests of hydrometallurgical extraction process from domestic uranium ore to uranium tetrafluoride, extracted at Ningyo-toge. Yotsugi Mill Tailings Pond was constructed for the purpose of depositing slag and other things generated due to the operation of the smelter. Furthermore supernatant water from the deposition field had been treated appropriately at wastewater treatment facilities, which has been provided in the downstream site of the pond. We have been utilizing the Yotsugi Mill Tailings Pond as a temporary storage field of mine water generated from the old mining gallery, mainly. After filing an abolition report of facilities of the smelter, with the completion of industrial trials of refinery in 1982. Ningyo-toge environmental engineering center has studied for processing uranium and radium, in wastewater, which must be reduced more safely by advancing these processing technical development. Supernatant water of The Pond is treated at the wastewater treatment facilities before discharging to Ikegogawa-river. And those collateralize the emission standards to discharge to the river set at the Center with continuing stable processing. This document summarized the history of the wastewater treatment, technical development for the water treatment, and the current situation of the water treatment.
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.
Sakao, Ryota; Saito, Hiroshi; Torikai, Kazuyoshi; Taki, Tomihiro
Journal of MMIJ, 130(6), p.275 - 278, 2014/06
Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency has been managing the Ningyo-toge Uranium Mine and Togo Uranium Mine in accordance with the Mine Safety laws. This paper shows a summary of the remediation activities of Mill Tailings Pond including the strategy and monitoring.
Takayama, Yusuke*; Ikuta, Yuki*; Iizuka, Atsushi*; Kawai, Katsuyuki*; Taki, Tomihiro; Sakao, Ryota; Ichikawa, Yasuaki*
Unsaturated Soils; Research & Applications, p.659 - 665, 2014/06
In this paper, a multiple unsaturated soil barrier consisting of gravel, sand and bentonite-mixed soil layers is considered as a hardly permeable covering to prevent rainwater from infiltrating into waste deposits. Not only the quite low permeability of bentonite-mixed soil layer but also a function of capillary barrier between granular layers having different water-retention capabilities is expected to prevent water infiltration. A series of numerical simulation is carried out to evaluate performance of the multiple soil barrier using saturated/unsaturated soil/water coupled FE computation technique. The multiple unsaturated soil barrier system considered here is 10m long and 1.5 m thick consisting of sandy soil surface, sand filter, gravel layer, sand filter and bentonite-mixed clayey layer. And the soil barrier system is assumed to be placed as a covering with a 5% inclination on the waste deposit. The performance of the multiple soil barrier system is shown as a management chart to maintain impermeable ability associated with possible rainfall intensity. Particularly, in this paper, actual rainfall record in Okayama area is employed to determine the rainfall intensity which is imposed as a boundary condition in the computation. According to the simulation results, it is found that the capillary barrier is a key issue in evaluating the long term performance of the barrier system. And, it is confirmed that the barrier system considered in this paper can work well against the maximum intensity of the rainfall in the past record.
Fukushima, Shigeru; Taki, Tomihiro; Saito, Hiroshi; Torikai, Kazuyoshi; Sato, Yasushi*
Nihon Chikasui Gakkai 2013-Nen Shuki Koenkai Koen Yoshi, p.258 - 263, 2013/10
no abstracts in English
Saito, Hiroshi; Taki, Tomihiro
Proceedings of 15th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2013) (CD-ROM), 4 Pages, 2013/09
Ningyo-toge Environmental Engineering Center has been managing the Ningyo-toge Uranium Mine. The Mine is subject to environmental remediation to ensure the radiation protection from the exposure pathways to humans in future, and to prevent occurrence of mining pollution. The Yotsugi Mill Tailings Pond is considered as the highest prioritized facility. So far, capping is put on the stable upstream part of the Pond to reduce dose rate, radon exhalation and rainwater precipitation. Prior to its construction, it was decided that the capping are to be multi-layered and natural materials are to be used, and the capping specifications were decided. Also, drainage channels and gabion work are constructed around the capping and at the foot of capping slope, respectively. Monitoring, which will continue for years, has started to confirm the effectiveness of the capping and the data will be utilized for the future remediation of the downstream of the Pond.
Saito, Hiroshi; Taki, Tomihiro
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.533 - 537, 2010/10
Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency (JAEA) has maintained and preserved the Ningyo-toge and Togo Mines under the related laws, including the Mine Safety Law. JAEA has been planning to close these mines to prevent mine-pollution and reduce radiological impact to as low as achievably possible, for lasting protection of individuals and the environment. Among the mine-related facilities that are subject to environmental remediation, the Mill Tilings Pond is given the top priority. So far, basic concept has been discussed in parallel with data acquisition and designing for some of remediation activities.
Saito, Hiroshi; Taki, Tomihiro
Journal of MMIJ, 126(6), p.239 - 242, 2010/05
Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency (JAEA) has maintained and preserved the Ningyo-toge and Togo Mines under the related laws, including the Mine Safety Law. JAEA has been planning to close these Mines to prevent mine-pollution and reduce radiological impact to as low as achievably possible, for lasting protection of individuals and the environment. Among the mine-related facilities that are subject to environmental remediation, the Mill Tilings Pond is given the top priority. So far, basic concept has been discussed in parallel with data acquisition and designing for some of remediation activities.
Mitamura, Hisayoshi; Naganawa, Hirochika; Nagano, Tetsushi; Yanase, Nobuyuki; Hanzawa, Yukiko; Shimojo, Kojiro; Matsubara, Tatsuo; Mita, Yutaka; Taki, Tomihiro; Murata, Masato
JAEA-Research 2008-113, 27 Pages, 2009/03
JAEA-Research-2008-113.pdf:31.84MB
An effective mass processing equipment using solvent extraction method, named "emulsion flow extractor," is the most promising apparatus for removal and recovery of uranium from liquid waste originated from decontamination of uranium-contaminated fluoride waste in the uranium conversion test facility and of used gas centrifuges in the uranium enrichment facility at Ningyo-toge environmental engineering center. Prior to application of the emulsion flow extractor for actual uranium-containing liquid waste, properties of some phosphorous extractants for extraction and separation of uranium and constituents from simulated liquid wastes were examined through batch tests. These preliminary tests revealed that D2EHPA would be a promising candidate for extractant used for treatment of the actual uranium-containing liquid wastes, and that the extractants with a surfactant like AOT would not be useful.
Naganuma, Masaki; Taki, Tomihiro
JAEA-Conf 2006-007, p.55 - 58, 2006/06
no abstracts in English
Taki, Tomihiro; Komoto, Shigetoshi; Otomura, Keiichiro; Takenaka, Toshihide*; Sato, Nobuaki*; Fujino, Takeo*
Journal of Nuclear Science and Technology, 32(9), p.880 - 888, 1995/00
None
Sato, Yasushi; Taki, Tomihiro; Saito, Hiroshi; Onishi, Toshimitsu*; Sakamoto, Atsushi*
no journal, ,
no abstracts in English
Ikuta, Yuki*; Takayama, Yusuke*; Tsurumi, Shuhei*; Ichikawa, Yasuaki*; Iizuka, Atsushi*; Kawai, Katsuyuki*; Taki, Tomihiro; Sakao, Ryota
no journal, ,
As a part of remediation of closed uranium mine, "Yotsugi Mill Tailings Pond" has been remediated in Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency. The aim of remediation is to take measures to reduce the load of water treatment and the radon exposure to humans in future, and to prevent the occurrence of relevant environmental contamination. So far, the upstream of the Pond has been covered by the multi-layered capping in which layers are set to use gravel, sand and decomposed granite soil to drain penetrated rainwater to the neighboring river. This capping system needs to be monitored on a long-term basis and to be evaluated to work as expected in advance, therefore seepage analysis and settlement analysis has carried out. As a result, Settlement of analysis was well accorded with measured value and marked change of saturation accompanied by rain was not observed in the seepage analysis.
Sasaki, Yosuke*; Takayama, Yusuke*; Ikuta, Yuki*; Iizuka, Atsushi*; Kawai, Katsuyuki*; Sakao, Ryota; Taki, Tomihiro
no journal, ,
As part of environmental remediation of Ningyo-toge Uranium Mine, multi-layered capping is constructed to reduce rainwater infiltration at the upstream of the Mill Tailings Pond. Settlement is expected due to consolidation characteristics of mill tailings and clayish sediments which exist below capping. Numerical simulation is carried out to expect the settlement amount during and after the capping construction. Settlement amount has been measured periodically, and the simulation result and measurement data are compared to evaluate the simulation method.
Iwasaki, Keisuke*; Kimoto, Kazushi*; Okubo, Kenji*; Awai, Sohei*; Sakao, Ryota; Taki, Tomihiro
no journal, ,
no abstracts in English
