Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2021

Nakada, Akira; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Futagawa, Kazuo; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; et al.

JAEA-Review 2022-078, 164 Pages, 2023/03

JAEA-Review-2022-078.pdf:2.64MB

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 2021 to March 2022. 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 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.

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2015

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Hosomi, Kenji; Nagaoka, Mika; Hokama, Tomonori; Yokoyama, Hiroya; Nishimura, Tomohiro; Matsubara, Natsumi; Maehara, Yushi; et al.

JAEA-Review 2016-035, 179 Pages, 2017/03

JAEA-Review-2016-035.pdf:4.2MB

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 2015 to March 2016. 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.

-edge jump and shift on white-line of Pd interlayer for trilaminar neutron production target under H irradiation

Ishiyama, Shintaro; Fujii, Ryo*; Nakamura, Masaru*; Imahori, Yoshio*

Journal of Chemistry and Chemical Engineering, 8(9), p.870 - 875, 2014/09

https://doi.org/10.17265/1934-7375/2014.09.005

Interlayer Pd for the Li/Pd/Cu neutron target for BNCT (Boron Neutron Capture Therapy) was characterized after 0.1-5 keV H irradiation by XAFS technique, and following conclusions were derived; (1) From the XAFS observation of white line of Pd, remarkable Pd Edge jump was found in 1.1-3 times higher than before irradiation in low irradiation fluence. (2) This fact indicates increase of hole density in Pd 4d-band, whereas no change was observed for XASF spectra of Ag sample under the same irradiation conditions. (3) Remarkable Pd Edge shift of 0.12-0.66 eV was also found with increase of H irradiation energy in low fluence, and drastically decreased after peak in high irradiation energy and fluence.(4)Implanted protons deposited in Pd as negative under the balance of electron population enhanced by proton irradiation and charge transfer.

Surficial chemical states of LiN synthesized on lithium target for boron neutron capture therapy

Ishiyama, Shintaro; Baba, Yuji; Fujii, Ryo*; Nakamura, Masaru*; Imahori, Yoshio*

Nihon Kinzoku Gakkai-Shi, 78(8), p.322 - 325, 2014/08

https://doi.org/10.2320/jinstmet.J2014022

To remove high level of contaminants by O and C from LiN surface for boron neutron capture therapy target, high temperature thermal desorption was conducted up to 1123 K in ultra high vacuum and the following results were derived; (1) During thermal desorption up to 1023 K, typical three peaks of vacuum pressure disturbance due to vaporization of contaminants were observed in vacuum pressure-temperature curve. (2) Over-layered contaminants with high melting temperature below 1023 K on LiN surface is completely removed by high temperature thermal desorption up to 1123 K in ultra high vacuum. (3) From these desorption results, it is suggested that these contaminants corresponding to these vaporization peaks are HO and Li compounds with high melting temperature below 1023 K, of which LiOH and LiCO were synthesized by decomposition process of LiN with residual HO and CO in low temperature.

3KeV H irradiation to Li/Pd/Cu trilaminar neutron production target for BNCT

Ishiyama, Shintaro; Fujii, Ryo*; Nakamura, Masaru*; Imahori, Yoshio*

Materials Transactions, 55(4), p.658 - 663, 2014/03

https://doi.org/10.2320/matertrans.M2013403

The Li/Pd/Cu trilaminar structures of the synthesized target for BNCT were characterized under 3keV H irradiation by XPS and XAFS technique, which provides structural/electronic properties of solids, and information about the local structure, such as the nature and number of surrounding atoms and inter-atomic distances. Following conclusions were derived; (1) Pd-Cu physical bonding was produced between the Pd and Cu interface by electro-less plating Pd deposition on a high purity Cu plate (2) From the XAFS observation of white line of Pd, the Pd 3 Edge jump was found after H irradiation, this fact indicates increase of hole density in Pd 4-band. (3) 0.9 eV chemical shift was also observed in Pd 3 white line for Pd/Cu samples, which will affect the quality of the Li/Pd/Cu target due to the formation of PdH in palladium insert layer.

Low temperature and pressure synthesis of lithium-nitride compound with HO addition on lithium target for BNCT

Ishiyama, Shintaro; Baba, Yuji; Fujii, Ryo*; Nakamura, Masaru*; Imahori, Yoshio*

Materials Transactions, 54(12), p.2233 - 2237, 2013/12

https://doi.org/10.2320/matertrans.M2013242

Low temperature synthesis of lithium-nitride compound was conducted on the lithium target for BNCT by N/HO mixing gas squirt in ultra high vacuum chamber, and the following results were derived; (1) Lithium-nitride compound was synthesized on lithium target under 101.3 PaN gas squirt at room temperature and 1 10 Pa in ultra high vacuum chamber. (2) Remarkable contamination by O and C was observed on the lithium-nitride compound synthesized by 13.3 80 Pa/1.33 4.7 Pa N/HO mixing gas squirt. (3) No contamination and synthesis of Li-N compound was observed at 0.013 0.027 Pa/0 0.005 Pa N/HO squirt. (4) Contamination by O and C is enhanced with excessive addition of over 1.33 Pa HO addition.

Thermal stability of BNCT neutron production target synthesized by lithium deposition and ion implantation

Ishiyama, Shintaro; Baba, Yuji; Fujii, Ryo*; Nakamura, Masaru*; Imahori, Yoshio*

Materials Transactions, 54(9), p.1760 - 1764, 2013/09

https://doi.org/10.2320/matertrans.M2013062

LiN synthesis on Li deposition layer was conducted without HO and O by lithium deposition in high vacuum chamber of 10 Pa and ion implantation techniques and the thermo-chemical stability of the LiN/Li/Cu tri-layered target under laser heating and air exposure was characterized by X-ray photoelectron spectroscopy. Following conclusions were derived; (1) LiN/Li/Cu tri- layered target with very low oxide and carbon contamination was synthesized by lithium deposition and ion implantation techniques without HO and O additions and frequent synthesis of the target is possible. (2) The evaporating temperature of Li deposited layer increased by 120 K after forming the LiN layer on the surface of Li. (3) Remarkable oxidation and carbon contamination were observed on the surfaces of Li/Cu and LiN/Li/Cu after air exposure and these contaminated compositions formed on the surface of LiN/Li/Cu was not removed by Ar heavy sputtering.

Synthesis of lithium nitride for neutron production target of BNCT by lithium deposition and ion implantation

Ishiyama, Shintaro; Baba, Yuji; Fujii, Ryo*; Nakamura, Masaru*; Imahori, Yoshio*

Nuclear Instruments and Methods in Physics Research B, 293, p.42 - 47, 2012/12

https://doi.org/10.1016/j.nimb.2012.09.016

To achieve high performance of BNCT (Boron Neutron Capture Therapy) device, lithium nitride target for neutron production was synthesized by in-situ vacuum deposition and nitridation techniques. Following conclusions were derived; (1) Uniform lithium layer of a few hundreds nanometer was formed on Pd/Cu multilayer surface by vacuum deposition technique using metallic lithium as a source material. (2) Lithium nitrides were formed by nitridation by the implantation of low-energy nitrogen ions on the deposited lithium layer surface. The chemical states of the nitridated zone were close to the stoichiometric lithium nitride, LiN. (3) This nitridated zone formed on surface of four layered lithium target is stable for three months in air condition. The nitridation is effective to protect lithium target from degradation by unfavourable reactions.