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Hirata, Sakiko*; Kusaka, Ryoji; Meiji, Shogo*; Tamekuni, Seita*; Okudera, Kosuke*; Hamada, Shoken*; Sakamoto, Chihiro*; Honda, Takumi*; Matsushita, Kosuke*; Muramatsu, Satoru*; et al.
Inorganic Chemistry, 62(1), p.474 - 486, 2023/01
Times Cited Count：0 Percentile：0.01(Chemistry, Inorganic & Nuclear)Takahashi, Yutaka*; Mikoshiba, Masumi*; Shimura, Toshiaki*; Nagata, Mitsuhiro; Iwano, Hideki*; Danhara, Toru*; Hirata, Takafumi*
Island Arc, 30(1), p.e12393_1 - e12393_15, 2021/01
Times Cited Count：2 Percentile：16.39(Geosciences, Multidisciplinary)The Hidaka metamorphic belt is an excellent example of island-arc-type crust, and in this belt the metamorphic grade increases westwards from unmetamorphosed sediment up to the granulite facies. The metamorphic age of the belt had previously been considered to be ca. 55 Ma. However, zircons from the granulites in the lower sequence have given U-Pb ages of ca. 21-19 Ma and a preliminary report on zircons from pelitic gneiss in the upper sequence gave a U-Pb age of ca. 40 Ma. In this paper we provide new U-Pb ages for zircons from the pelitic gneisses in the upper sequence in order to assess the metamorphic age and also the maximum depositional age of the sedimentary protolith. The weighted mean 
Pb/
U ages and 2 sigma errors for zircons from biotite gneiss in the central area of the belt are 39.6 
0.9 Ma for metamorphic overgrowth rims and 53.1 0.9 Ma for the youngest inherited detrital cores. The ages of zircons from cordierite-biotite gneiss in the southern area are 35.9 0.7 Ma for overgrowth rims and 46.5 2.8 Ma for the youngest detrital cores. These results indicate that the metamorphism of the upper sequence took place at ca. 40-36 Ma, and that the sedimentary protolith was deposited after ca. 53-47 Ma. These metamorphic ages are consistent with the reported ages of ca. 37-36 Ma plutonic rocks in the upper sequence, but contrast with the ca. 21-19 Ma ages of metamorphic and plutonic rocks in the lower sequence. Therefore, we conclude, that the upper and lower metamorphic sequences developed independently but became coupled before ca. 19 Ma as a result of dextral reverse tectonic movements, as indicated by the intrusion of ca. 19-18 Ma magmas, possibly generated in the lower sequence, into the upper sequence.
Horiguchi, Kenichi; Sugaya, Atsushi; Saito, Yasuo; Tanaka, Kenji; Akutsu, Shigeru; Hirata, Toshiaki
Proceedings of 2009 International Congress on Advances in Nuclear Power Plants (ICAPP '09) (CD-ROM), p.9411_1 - 9411_9, 2009/05
The low-level radioactive Waste treatment Facility (LWTF) was constructed at the Tokai Reprocessing Plant (TRP) and cold test has been carried out since 2006. The waste which is treated in the LWTF is combustible/incombustible solid waste and liquid waste. In the LWTF, The combustible/incombustible solid waste will be incinerated. The liquid waste will be treated by the radio-nuclides removal process subsequently solidified by cement materials. This report describes the essential technologies of the LWTF and results of R&D work for the nitrate-ion decomposition technology for the liquid waste.
Narumi, Kazumasa; Saito, Yuichi; Chiba, Atsuya; Adachi, Masahiro; Naramoto, Hiroshi*; Seki, Shu*; Hirata, Koichi*; Iwase, Akihiro*; Kaneko, Toshiaki*; Shibata, Hiromi*
no journal, ,
no abstracts in English
Sugaya, Atsushi; Horiguchi, Kenichi; Saito, Yasuo; Tanaka, Kenji; Akutsu, Shigeru; Hirata, Toshiaki
no journal, ,
The Low-level radioactive Waste Treatment Facility (LWTF) was constructed at the Tokai Reprocessing Plant and cold testing has been performed since 2006. The aims of this facility are to provide safe, effective and economic treatment of the Waste. The wastes treated in the LWTF are combustible and incombustible solid waste and liquid waste. The problem of burning up incombustible waste is to generate chlorine gas which causes corrosion. The incinerator is made of corrosion resistant metal and uses cooling water to prevent corrosion. The radio-nuclides separation process is newly-introduced for low-level radioactive liquid waste to reduce the deep geological disposal cost. A large amount of nitrate in the liquid waste might cause the environmental pollution. Nitrate ion decomposition technology is under development. A cement based encapsulation method to immobilize those liquid wastes has been developed. The results of these R&D work will be adopted in the LWTF in the near future.
