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Journal Articles

Harmless treatment of radioactive liquid wastes for safe storage in systematic treatment of radioactive liquid waste for decommissioning project

Nakahara, Masaumi; Watanabe, So; Aihara, Haruka; Takahatake, Yoko; Arai, Yoichi; Ogi, Hiromichi*; Nakamura, Masahiro; Shibata, Atsuhiro; Nomura, Kazunori

Proceedings of International Conference on Nuclear Fuel Cycle; Sustainable Energy Beyond the Pandemic (GLOBAL 2022) (Internet), 4 Pages, 2022/07

Various radioactive wastes have been generated from Chemical Processing Facility for basic research on advanced reactor fuel reprocessing, radioactive waste disposal, and nuclear fuel cycle technology. Many types of reagents have been used for the experiments, and some troublesome materials were produced in the course of experiments. The radioactive liquid wastes were treated for stable and safe storage using decomposition, solvent extraction, precipitation, and solidification methods. In this study, current status of harmless treatment for the radioactive liquid wastes would be reported.

Journal Articles

Effect of water radiolysis on surface oxide film formed on SUS316L in $$gamma$$-ray irradiated high temperature water

Yamamoto, Masahiro; Kato, Chiaki; Sato, Tomonori; Nakahara, Yukio; Tsukada, Takashi; Watanabe, Atsushi*; Fuse, Motomasa*

Proceedings of Annual Congress of the European Federation of Corrosion (EUROCORR 2013) (CD-ROM), 5 Pages, 2013/09

Major corrosion problems of light water reactor (LWR) which are represented by stress corrosion cracking are affected by dissolved oxygen (DO) concentration in feed water. Many corrosion tests were conducted with the parameter of DO values. Oxygen source of an actual LWR is radiolysis of cooling water and also H$$_{2}$$O$$_{2}$$ is generated. The effect of these species created by water radiolysis to corrosion of structural material was not sufficiently examined. $$gamma$$-ray irradiated experiments were conducted in high temperature water condition using type 316L stainless steels with crevice. The calculation of radiolysis products was not estimated by the effect of radiolysis products. From these results, much complicated reaction seemed to occur at the $$gamma$$-ray irradiated crevice portion.

Journal Articles

Effects of $$gamma$$-ray irradiation and crevice-like shape on the corrosion of type 316L stainless steel in high-temperature water

Nakahara, Yukio; Kato, Chiaki; Yamamoto, Masahiro; Watanabe, Atsushi*; Fuse, Motomasa*

Proceedings of Symposium on Water Chemistry and Corrosion in Nuclear Power Plants in Asia 2009 (CD-ROM), p.226 - 231, 2009/10

The irradiation effect to high-temperature water in nuclear power plant has been regarded as one of important issues for preventing corrosion and stress corrosion cracking of plant materials. However, the effects of surface reaction and configurations of material on irradiated high-temperature water chemistry have been studied little because of the difficulty of measuring the environment. In this work, we have done a series of corrosion tests of Type 316L stainless steel in high-temperature water in order to estimate the effects of $$gamma$$-ray irradiation and crevice-like shape on the water chemistry. Test specimens immersed in high-temperature water of 288 $$^{circ}$$C were $$gamma$$-ray irradiated for 500 hours. The absorbed dose rate of $$gamma$$-ray irradiation was estimated to be 30 kGy h$$^{-1}$$. The dimensions of the disk-like specimens were 16 mm in diameter by 0.5 mm in thickness. The surfaces of the specimens were mechanically finished with #800 emery paper. Sets of two specimens attached closely in order to simulate a crevice-like environment were also immersed. The surfaces of the specimens were analyzed using SEM, TEM, and laser Raman spectrometer. The results of surface analyses indicated that $$gamma$$-ray irradiation enhanced the precipitation of iron oxide on the surface and the thickness of inner oxide layer became thicker by $$gamma$$-ray irradiation. $$gamma$$-ray irradiation also changed the morphology of oxide on the surface faced to the crevice-like environment.

Journal Articles

Research and development of crystal purification for product of uranium crystallization process

Yano, Kimihiko; Nakahara, Masaumi; Nakamura, Masahiro; Shibata, Atsuhiro; Nomura, Kazunori; Nakamura, Kazuhito*; Tayama, Toshimitsu; Washiya, Tadahiro; Chikazawa, Takahiro*; Kikuchi, Toshiaki*; et al.

Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.143 - 150, 2009/09

Journal Articles

Effects of $$gamma$$-ray irradiation on the high temperature oxidation of austenitic stainless steel in supercritical water

Nakahara, Yukio; Yamamoto, Masahiro; Karasawa, Hidetoshi*; Kiuchi, Kiyoshi; Katsumura, Yosuke*

Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10

Three types of commercial-grade austenitic stainless steel, Type 304L, Type 316L, and Type 310S, were immersed in deaerated supercritical water (SCW) of 25 MPa, 550 $$^{circ}$$C with $$gamma$$-ray irradiation for 1000 hours in total. Absorbed dose rates in SCW are estimated at 5-15 kGy h$$^{-1}$$. High temperature oxidation experiments resulted in the formation of two-layer oxide film in which the outer layer is porous iron oxide and the inner layer is dense iron-chromium-nickel oxide. Rate constants of parabolic rate law in net weight gains of Type 304L SS and Type 310S SS are decreased as the $$gamma$$-ray exposure rate is increased. The net weight gain of $$gamma$$-ray irradiated Type 316L SS is sharply fluctuating and decreasing, because the flaking of the outer layer occurred. Hematite is formed in the outer layer on all irradiated samples of examined alloys. The concentration of chromium on the surface is increased by $$gamma$$-ray irradiation. A chromium-rich part in the inner layer accompanying a nickel-rich part in the metal is formed along to the oxide/metal interface of $$gamma$$-ray irradiated Type 304L SS, non-irradiated and $$gamma$$-ray irradiated Type 316L SS.

Journal Articles

Research activities for development of CTBT-related technologies in JAERI

Shinohara, Nobuo; Asano, Yoshie; Hirota, Naoki*; Hokida, Takanori; Inoue, Yoji; Kumata, Masahiro; Nakahara, Yoshinori*; Oda, Tetsuzo*; Uchikoshi, Takako*; Yamamoto, Yoichi

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 3 Pages, 2005/10

Research activities of JAERI related to the CTBT verification regime are presented in the International Conference. The subjects of this presentation are (1) an overview of the CTBT verification regime, (2) construction and operation of the radionuclide monitoring stations of Okinawa (RN37) and Takasaki (RN38) and the certified radionuclide laboratory (RL11), and (3) preparation of the National Data Center at Tokai (JAERI NDC) for radionuclide data. The RN38 station has been certified by the CTBTO/PrepCom and sending the measured data every day. The infrastructures and operational manuals for RN37 and RL11 are now preparing for their operations. The JAERI NDC has experimentally analyzed and evaluated the radionuclide data from all over the world through International Data Center (IDC). As an example of the JAERI NDC works, atmospheric dispersion backtracking system has been developing by using WSPEEDI (Worldwide Version of System for Prediction of Environmental Emergency Dose Information) code to estimate a source location of radionuclide release by nuclear explosion/accident.

Journal Articles

Status of research activities for development of CTBT-related technologies in JAERI

Shinohara, Nobuo; Inoue, Yoji; Uchikoshi, Takako*; Oda, Tetsuzo*; Kumata, Masahiro; Kurosawa, Yoshiaki; Hirota, Naoki*; Hokida, Takanori; Nakahara, Yoshinori*; Yamamoto, Yoichi

Dai-25-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.51 - 58, 2005/00

The Japan Atomic Energy Research Institute (JAERI) conducts researches and developments related to Comprehensive Nuclear-Test-Ban Treaty (CTBT) on the basis of Japan's pragmatic and progressive efforts toward peaceful use of atomic energy and non-proliferation with the goal of realizing a peaceful and safe world free from nuclear weapons. The Treaty aims for the establishment of a global verification regime comprising an International Monitoring System (IMS) and the JAERI has engaged in the following activities: construction and operation of the radionuclide monitoring stations at Okinawa (RN37) and Takasaki (RN38) and the certified radionuclide laboratory at Tokai (RL11) as specified in Annex 1 of CTBT Protocol, and preparation of the National Data Center at Tokai (JAERI NDC). Research activities of JAERI related to the CTBT verification regime are presented in the paper. The subjects of this presentation are (1) an overview of the CTBT verification regime, (2) construction and operation of RN37, RN38 and RL11, and (3) preparation of the JAERI NDC for radionuclide data.

JAEA Reports

Recent status of research activities for development of CTBT-related technologies in JAERI

Hirota, Naoki*; Hokida, Takanori; Inoue, Yoji; Kumata, Masahiro; Kurosawa, Yoshiaki; Miyamoto, Yutaka; Nakahara, Yoshinori; Oda, Tetsuzo; Shinohara, Nobuo; Uchikoshi, Takako*; et al.

JAERI-Review 2003-021, 68 Pages, 2003/08

JAERI-Review-2003-021.pdf:9.73MB

This report describes research activities of the R & D Group for Non-Proliferation Technology related to the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification regime. The main subjects of this report are (1) an overview of the CTBT verification regime, (2) preparation of the National Data Center for radionuclide data, (3) construction and operation of the radionuclide monitoring stations at Takasaki and Okinawa and the certified rarionuclide laboratory at Tokai in Japan. We have participated in an intercomparison test internationally organized for the certified laboratories and the test results are given here. Scientific application of the CTBT-related technologies to environmental researches is also depicted.

Journal Articles

Present state of JAERI National Data Center (NDC) for CTBT verification

Yamamoto, Yoichi; Hokida, Takanori; Hirota, Naoki*; Oda, Tetsuzo; Nakahara, Yoshinori; Kumata, Masahiro; Inoue, Yoji; Uchikoshi, Takako*; Shinohara, Nobuo; Usuda, Shigekazu

Dai-23-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.53 - 60, 2002/12

The Japan Atomic Energy Research Institute (JAERI) has developed the National Data Center (NDC) for radionuclide as part of the international monitoring regime related to the Comprehensive Nuclear-Test-Ban Treaty (CTBT). JAERI NDC already started to input gamma-ray spectrum data obtained from several International Monitoring System (IMS) stations into a database. Data analysis reports made by the International Data Center (IDC) are also stored in the database. Some software tools are under development for the NDC's independent analysis such as investigation of existence of the radionuclides derived from nuclear explosion and presumptive analysis of source location of radionuclide release. The NDC system will also be able to post IMS data and analysis results to the authorized users on the Internet. This paper presents the role, current state of system development and future plan of JAERI NDC.

Journal Articles

The Present status and issues on establishment of the CTBT verification regime

Oda, Tetsuzo; Kumata, Masahiro; Nakahara, Yoshinori; Yamamoto, Yoichi; Hokida, Takanori; Hirota, Naoki*; Uchikoshi, Takako*; Inoue, Yoji; Shinohara, Nobuo

Dai-23-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.29 - 37, 2002/12

The Comprehensive nuclear Test-Ban Treaty(CTBT) bans all nuclear explosions and also calls for a verification regime, which consists of the International Monitoring System(IMS) and On-site Inspection. The primary objectives of the IMS are to deter nuclear explosions in all environments and, if such an explosion does occur, to detect, locate, and identify its source. The CTBT was opened for signature on September 24, 1996 and the Preparatory Commission(PrepCom) for the CTBT Organization was established to prepare for the verification regime in order to monitor compliance with the Treaty. The Preparatory Commission comprises two main organs: a plenary body of all the States Signatories as the highest policy-making organ, and the Provisional Technical Secretariat(PTS). The plenary body has three subsidiary bodies: Working Group A(administrative matters and legal issues), Working Group B(verification issues), and an Advisory Group. This paper presents an overview and mandate of the PrepCom, and status of verification regime, and discusses future activities.

Journal Articles

Radionuclide monitoring stations in CTBT verification regime

Kumata, Masahiro; Oda, Tetsuzo; Miyamoto, Yutaka; Uchikoshi, Takako*; Nakahara, Yoshinori; Yamamoto, Yoichi; Hokida, Takanori; Hirota, Naoki*; Inoue, Yoji; Shinohara, Nobuo

Dai-23-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.39 - 44, 2002/12

The International Monitoring System (IMS) will be established across the world to verify compliance with the Comprehensive Test Ban Treaty (CTBT). The IMS will be capable of detecting and identifying nuclear explosions of detonated within the atmosphere, underwater and underground. 321 monitoring stations will be set around the world as a monitoring network of the IMS. The four technologies of seismology, hydroacoustic, infrasound, and radionuclide will be used for monitoring purposes. In order to build the radionuclide monitoring network, 80 radionuclide stations were chosen. Particles in the atmosphere are collected on a filter at each station to measure radioactivity by a HP-Ge detector. Further, 40 out of these 80 stations will be equipped with an automatic radioactive noble gas sampler/analyzer. The JAERI is establishing infrastructure to host radionuclide air monitoring equipment for two raionuclide stations in Japan. This paper presents the current status of the establishment and promising performance of the stations in Japan.

Journal Articles

JAERI-Tokai radionuclide laboratory in CTBT verfication regime

Shinohara, Nobuo; Yamamoto, Yoichi; Inoue, Yoji; Kumata, Masahiro; Oda, Tetsuzo; Uchikoshi, Takako*; Hokida, Takanori; Hirota, Naoki*; Nakahara, Yoshinori; Usuda, Shigekazu

Dai-23-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.45 - 52, 2002/12

no abstracts in English

JAEA Reports

Integration study (IV) for performance assessment system of geological disposal

Yanagisawa, Ichiro*; Ezaki, Masahiro*; Ishihara, Yoshinao*; Fusaeda, Shigeki*; Mukai, Satoru*; Doi, Hideo*; Maeda, Kazuto*; Nakahara, Yutaka*

PNC TJ1214 93-001, 544 Pages, 1993/03

PNC-TJ1214-93-001.pdf:16.47MB

None

Oral presentation

Effect of $$gamma$$ ray irradiation on the corrosion of stainless steel in supercritical water

Nakahara, Yukio; Karasawa, Hidetoshi*; Yamamoto, Masahiro; Kiuchi, Kiyoshi; Katsumura, Yosuke*

no journal, , 

A supercritical water-cooled nuclear reactor (SCWR) has been under review as one of advanced reactors. Corrosion tests of several types of stainless steel in supercritical water (25MPa, 400$$sim$$500$$^{circ}$$C) were executed under $$gamma$$ ray irradiation in order to clarify the effect of $$gamma$$ ray on the corrosion. The results of the tests shows that the corrosion of stainless steel was progressed by the growth and degradation of surface oxide film, the dependence of the parabolic rate law constant on temperature can be fit with Arrhenius' equation, $$gamma$$ ray irradiation changed the property of surface oxide film.

Oral presentation

Influence of $$gamma$$ ray irradiation on surface film structures of stainless steels created in super critical water environment

Yamamoto, Masahiro; Nakahara, Yukio; Karasawa, Hidetoshi*; Katsumura, Yosuke*

no journal, , 

Super critical water cooling reactor (SCWR), which has higher energy efficiency than existent reactor, has been planned and examined. To realize the SCWR system, it is important to ensure the reliabilities of the materials used in the super critical condition. Some types of stainless steels were immersed in super critical water with $$gamma$$-ray irradiated condition. After the test, the surface films of stainless steels were analyzed. It was found that hematite (Fe$$_{2}$$O$$_{3}$$) was formed on the surface of oxide film with $$gamma$$-ray irradiation. Contrastingly, complex oxide including Cr and Ni was formed on the surface without $$gamma$$-ray irradiation.

Oral presentation

Investigation of aging phenomena caused by corrosion of stainless steels, commercial pure titanium and titanium alloys in chemical plants using nitric acid

Hirose, Fumimasa*; Nakahara, Masahiro*; Ueno, Fumiyoshi; Uchiyama, Gunzo; Nojima, Yasuo*

no journal, , 

To study aging phenomena caused by corrosion of stainless steels, commercial pure titanium and titanium alloys in chemical plants using nitric acid, corrosion incidents, experiences of materials installation, corrosion tests results under actual and simulated environments were investigated in this report. The results were compared with literatures. As the results, it was clarified that corrosion of SUS304L and SUS310ELC were accelerated at heat affected zone and weld metal, respectively. In the cases of commercial pure titanium and titanium alloys, corrosion were accelerated at the portion in the environments without Ti ion. Finally, corrosion lives and application conditions of these materials in nitric acid environment were considered.

Oral presentation

Effects of $$gamma$$-ray irradiation on the high temperature oxidation of stainless steel in supercritical water

Nakahara, Yukio; Yamamoto, Masahiro; Kato, Chiaki; Kiuchi, Kiyoshi; Karasawa, Hidetoshi*; Katsumura, Yosuke*

no journal, , 

Corrosion experiments of stainless steel (SS) in supercritical water (SCW) have done with a flowing SCW loop including a $$gamma$$-ray irradiated autoclave. Three types of commercial-grade austenitic SS, Type 304L, Type 316L, and Type 310S, were examined. The condition of SCW was adjusted to the core environment of a SCW reactor system. Test samples of the SS were immersed in deaerated pure SCW (25 MPa, 550 $$^{circ}$$C). Feed water was circulated at a flow rate of 4 L h$$^{-1}$$. Absorbed dose rates near the surface of the test samples in SCW were estimated at 5-15 kGy h$$^{-1}$$. The time dependence of net weight gains followed parabolic rate law except $$gamma$$-ray irradiated Type 316L SS. The net weight gains of $$gamma$$-ray irradiated Type 304L SS and Type 310S SS were larger than those of the non-irradiated. Rate constants of parabolic rate law in net weight gains of Type 304L SS and Type 310S SS were decreased as the $$gamma$$-ray exposure rate was increased. The net weight gain of $$gamma$$-ray irradiated Type 316L SS was fluctuating and decreasing widely, because the exfoliation of the surface oxide occurred. On the surface of all the samples, the formation of two-layer oxide film in which the outer layer was porous iron oxide and the inner layer was dense iron-chromium-nickel oxide occurred. Iron oxide in the outer layer was magnetite (Fe$$_{3}$$O$$_{4}$$) with non-irradiated samples. Hematite ($$alpha$$-Fe$$_{2}$$O$$_{3}$$) was additionally formed in the outer layer with $$gamma$$-ray irradiated samples. A chromium-rich part in the inner layer was formed along to the oxide/metal interface of $$gamma$$-ray irradiated Type 304L SS.

Oral presentation

Research on improvements of the assessment technique of stress corrosion cracking

Tsukada, Takashi; Yamamoto, Masahiro; Miwa, Yukio; Kato, Chiaki; Nakano, Junichi; Nakahara, Yukio; Sato, Tomonori; Uchida, Shunsuke

no journal, , 

In order to develop a technical basis necessary to improve the assessment technique of SCC, in this research, the influence of water radiolysis and irradiation dose rate on SCC behavior were studied which was indispensable to understand SCC behavior in actual power plants. In addition, the present status of SCC assessment techniques were summarized and analyzed systematically, and the present issue to improve the techniques was extracted.

Oral presentation

Changes of the surface of SUS316L immersed in high-temperature water caused by $$gamma$$-ray irradiation

Nakahara, Yukio; Yamamoto, Masahiro; Ishijima, Yasuhiro; Kato, Chiaki

no journal, , 

500-hour experiments have been done in order to study the effects of $$gamma$$-ray irradiation (the absorption rate $$sim$$ 30 kGy/h) on the corrosion of 316L stainless steel immersed in high-temperature (288 $$^{circ}$$C) water. Difference between $$gamma$$-ray irradiated and non-irradiated specimen surfaces were discussed with the results of surface analyses after the experiments. TEM cross sections of the surfaces of specimens solely immersed in the water show that $$gamma$$-ray irradiation made surface oxide film thicker and the formation of oxide grains on the surface more apparent. The change of corrosive environment caused by the irradiation enhanced the precipitation of oxide on the surface. Surface analysis of crevice-simulating specimens was also done by laser Raman spectroscopy. No definite peak was seen in the spectrum of non-irradiated condition. The peaks of compound oxide of Fe, Ni, and Cr were seen in the spectrum of $$gamma$$-ray irradiated condition. These results should indicate that the change of corrosive environment inside the crevice caused by the irradiation promoted the corrosion.

Oral presentation

$$gamma$$-ray irradiation effects on the corrosion of type 316L stainless steel in a gap filled with high-tempertaure water

Nakahara, Yukio; Kato, Chiaki; Yamamoto, Masahiro; Tsukada, Takashi; Watanabe, Atsushi*; Fuse, Motomasa*

no journal, , 

no abstracts in English

25 (Records 1-20 displayed on this page)