Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2019

Nakano, Masanao; Fujii, Tomoko; Nemoto, Masashi; Tobita, Keiji; Seya, Natsumi; Nishimura, Shusaku; Hosomi, Kenji; Nagaoka, Mika; Yokoyama, Hiroya; Matsubara, Natsumi; et al.

JAEA-Review 2020-069, 163 Pages, 2021/02

JAEA-Review-2020-069.pdf:4.78MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2019 to March 2020. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2017

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Nemoto, Masashi; Tobita, Keiji; Kono, Takahiko; Hosomi, Kenji; Hokama, Tomonori; Nishimura, Tomohiro; Matsubara, Natsumi; et al.

JAEA-Review 2018-025, 171 Pages, 2019/02

JAEA-Review-2018-025.pdf:3.81MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2016 to March 2017. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.

Real-time observation of irradiated HeLa-cell modified by fluorescent ubiquitination-based cell-cycle indicator using synchrotron X-ray microbeam

Narita, Ayumi; Kaminaga, Kiichi; Yokoya, Akinari; Noguchi, Miho; Kobayashi, Katsumi*; Usami, Noriko*; Fujii, Kentaro

Radiation Protection Dosimetry, 166(1-4), p.192 - 196, 2015/09

https://doi.org/10.1093/rpd/ncv156

For the knowledge about irradiation effects of mammalian cells depending on the cell cycle, most of them had been analyzed by statistical approches. Our purpose is to establish the method for real-time observation of irradiated cells under a microscope. Fluorescent ubiquitination-based cell cycle indicator (FUCCI) human cancer (HeLa) cells (red indicates G1; green, S/G2) were exposed to a synchrotron X-ray microbeam. Cells in either G1 or S/G2 were selectively irradiated according to cell color observed in the same microscopic field in a culture dish. Time-lapse micrographs of the irradiated cells were acquired for 24 h after irradiation. The cell cycle was strongly arrested by irradiation at S/G2 and never progressed to G1. In contrast, cells irradiated at G1 progress to S/G2 with a similar time course as non-irradiated control cells. These results show single FUCCI cell exposure and live cell imaging are powerful methods for studying radiation effects on the cell cycle.

DNA damage by soft X-ray exposure at oxygen K-edge

Sugaya, Yuki; Narita, Ayumi; Fujii, Kentaro; Yokoya, Akinari

Journal of Physics; Conference Series, 502(1), p.012040_1 - 012040_4, 2014/04

https://doi.org/10.1088/1742-6596/502/1/012040

Water corrosion resistance of ODS ferritic-martensitic steel tubes

Narita, Takeshi; Ukai, Shigeharu; Kaito, Takeji; Otsuka, Satoshi; Matsuda, Yasushi*

Journal of Nuclear Science and Technology, 45(2), p.99 - 102, 2008/02

https://doi.org/10.3327/jnst.45.99

The oxide dispersion strengthened (ODS) ferritic-martensitic steels are being developing for application as advanced fast reactor cladding and fusion blanket materials, in order to allow increased operation temperature. Water corrosion test of ODS ferritic-martensitic steels was conducted under a controlled alkali water environment to evaluate the water corrosion behavior, comparing to conventional 17 mass% Cr austenitic stainless steel (PNC316) and 11 mass% Cr ferritic-martensitic stainless steel (PNC-FMS). It was showed that 9Cr-ODS martensitic steel and 12Cr-ODS ferritic steel have superior water corrosion resistance, and comparable to that of PNC316 and PNC-FMS at 333K for 1,000h under varying pH of 8.4, 10, 12.

Effects of tungsten on microstructure and high-temperature strength of oxide dispersion strengthened (ODS) martensitic steel

Narita, Takeshi*; Ukai, Shigeharu; Kaito, Takeji; Otsuka, Satoshi; Fujiwara, Masayuki

JAEA-Research 2006-050, 85 Pages, 2006/10

JAEA-Research-2006-050.pdf:133.32MB

In 9Cr ODS martensitic steel, tungsten(W) is a solid solution strengthening element, whose addition increases high-temperature strength by the combined effect with oxide dispersion strengthening. However, its excessive addition results in the increase of ferrite phase causing precipitation of intermetallic compound (Laves phase) under high temperature irradiation condition and thus ductility degradation. The amount of W addition therefore should be as low as possible. In this report, the effects of W on microstructure and high temperature mechanical properties of 9Cr ODS martensitic steels were examined for obtaining insights into optimum W concentration in terms of high-temperature strength and ductility. The results obtained are as follows: (1)In the 9CrODS martensitic steel, addition of W exceeding 2mass% is shown to cause precipitation of Laves phase which degrades the ductility and fracture toughness. It can be said that the current specification of W concentration, i.e. 2mass%W, is appropriate. (2)Hardness and tensile strength is shown to increase with W concentration. This increase is caused by the increase of solid solution strengthening and residual-alpha ferrite. The retainment of residual-alpha ferrite is enhanced by the addition of W (ferrite former element). The improvement of tensile strength at 973K provided by the solid solution strengthening is shown to be equivalent to that provided by the retainment of residual-alpha ferrite. (3)It would be open task to explorer an improved alloy design concept, i.e. decrease of W as low as possible and increase of residual-alpha ferrite. The degradation of high-temperature strength by decreasing W addition can be made up by the increasing fraction of residual-alpha phase that is provided by reduction of austenite former elements and increasing addition of ferrite former elements.

High temperature oxidation test of oxide dispersion strengthened (ODS) steel claddings

Narita, Takeshi; Ukai, Shigeharu; Kaito, Takeji; Otsuka, Satoshi; Matsuda, Yasushi*

JAEA-Research 2006-047, 100 Pages, 2006/07

JAEA-Research-2006-047.pdf:53.38MB

In a feasibility study of ODS steel cladding, its high temperature oxidation resistance was evaluated. Although addition of Cr is effective for preventing high temperature oxidation, excessively higher amount of Cr leads to embrittlement due to the Cr-rich ' precipitate formation. In the ODS steel developed by the Japan Atomic Energy Agency (JAEA), the Cr content is controlled in 9Cr-ODS martensite and 12Cr-ODS ferrite. In this study, high temperature oxidation test was conducted for ODS steels, and their results were compared with that of conventional austenitic stainless steel and ferritic-martensitic stainless steel. Following results were obtained in this study. (1)9Cr-ODS martensitic and 12Cr-ODS ferritic steel have superior high temperature oxidation resistance compared to 11mass%Cr PNC-FMS and even 17mass% SUS430 and equivalent to austenitic PNC316. (2)The superior oxidation resistance of ODS steel was attributed to earlier formation of the protective alpha-CrO layer at the matrix and inner oxide scale interface. The grain size of ODS steel is finer than that of PNC-FMS, so the superior oxidation resistance of ODS steel can be attributed to the enhanced Cr-supplying rate throughout the accelerated grain boundary diffusion. Finely dispersed Y2O3 oxide particles in the ODS steel matrix may also stabilized the adherence between the protective alpha-CrO layer and the matrix.

Effect of excess oxygen concentration on high-temperature strength of ODS martensitic steel

Otsuka, Satoshi; Ukai, Shigeharu; Fujiwara, Masayuki; Kaito, Takeji; Narita, Takeshi

JNC TN9400 2005-034, 197 Pages, 2005/08

JNC-TN9400-2005-034.pdf:28.06MB

Oxide dispersion strengthened(ODS) martensitic steel (9CrODS steel) has been identified as an attractive candidate for advanced fast reactor (FR) fuel cladding tube because of its superior high-temperature strength and radiation resistance. Our recent activities revealed that high-temperature strength of different lots of the cladding tubes is inconsistent each other, even though the same manufacturing process was applied to these tubes. This inconsistency means a critical problem that high-strength 9CrODS steel cladding tubes can not be manufactured reliably and consistently. In this report, a microstructure control technique for consistently and reliably manufacturing high-strength 9CrODS steel cladding tubes are examined based on a series of data concerning effect of excess oxygen concentration on high temperature strength and microstructure of 9CrODS steel.

Improvement of creep strength of 9CrODS martensitic steel by controlling excess oxygen and titanium concentrations

Otsuka, Satoshi; Ukai, Shigeharu; Kaito, Takeji; Narita, Takeshi; Fujiwara, Masayuki

Materials Transactions, 46(3), 487 Pages, 2005/00

https://doi.org/10.2320/matertrans.46.487

None

Manufacturing test of large scale hollow capsule and long length cladding in the large scale oxide dispersion strengthened (ODS) martensitic steel.

Narita, Takeshi; Ukai, Shigeharu; Kaito, Takeji; Otsuka, Satoshi; Fujiwara, Masayuki

JNC TN9400 2004-011, 141 Pages, 2004/04

JNC-TN9400-2004-011.pdf:12.79MB

Mass production capability of ODS martensitic steel claddinghas been evaluated in the feasibility studies on commercialized fast reactor cycle system. In this study, Manufacturing the large scale mother tube which has a high degree of accuracy in size, has been successfully carried out using large scale hollow capsule. For reducing the manufacturing cost of the ODS steel claddings, manufacturing process of the mother tubes using a large scale hollow capsules is promising.