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Sano, Naruto; Yamashita, Naoki; Watanabe, Masaya; Tsukada, Manabu*; Hoshino, Kazutoyo*; Hirai, Koki; Ikegami, Yuta*; Tashiro, Shinsuke; Yoshida, Ryoichiro; Hatakeyama, Yuichi; et al.
JAEA-Technology 2023-029, 36 Pages, 2024/03
JAEA-Technology-2023-029.pdf:2.47MB
At the Waste Safety Testing Facility (WASTEF), the gamma ray irradiation device "Gamma Cell 220" was relocated from the 4th research building of the Nuclear Science Research Institute in FY2019, and the use of gamma ray irradiation has begun. Initially, Fuel Cycle Safety Research Group, Fuel Cycle Safety Research Division, Nuclear Safety Research Center, Sector of Nuclear Safety Research and Emergency Preparedness, the owner of this device, conducted the tests as the main user, but since 2022, other users, including those outside the organization, have started using it. The gamma ray irradiation device "Gamma Cell 220" is manufactured by Nordion International Inc. in Canada. Since it was purchased in 1989, the built-in 60Co radiation source has been updated once, and safety research related to nuclear fuel cycles, etc. It is still used for this purpose to this day. This report summarizes the equipment overview of the gamma ray irradiation device "Gamma Cell 220", its permits and licenses at WASTEF, usage status, maintenance and inspection, and future prospects.
Yamashita, Naoki; Aoyama, Takahito; Kato, Chiaki; Sano, Naruto; Tagami, Susumu
JAEA-Technology 2023-028, 22 Pages, 2024/03
JAEA-Technology-2023-028.pdf:1.9MB
At the Fukushima Daiichi Nuclear Power Station (1F), which is currently undergoing decommissioning, there is growing interest in the effects of radiation-emitting radionuclides such as 
Sr and 
Cs on the structural integrity. In particular, the corrosion behavior of carbon steel, which is used in many parts of 1F, is known to change depending on metal cations in solution, but the effects of Sr and Cs on corrosion are not yet understood. In addition, it is important to investigate the distribution of Sr and Cs in the rust layer in order to understand the corrosion behavior, but the method has not yet been established. In this study, a glove box was prepared to conduct corrosion tests of carbon steel in NaCl containing Sr and Cs in the glove box. In addition, in order to clarify the influence of Sr and Cs, which exist as metal cations in the solution, on the corrosion behavior of carbon steel, we attempted to establish a detection method for radioactive materials in the rust layer using an imaging plate.
Yamashita, Naoki; Irisawa, Eriko; Kato, Chiaki; Sano, Naruto; Tagami, Susumu
JAEA-Technology 2022-035, 29 Pages, 2023/03
JAEA-Technology-2022-035.pdf:2.54MB
In the treatment process of the current commercial reprocessing plant (Rokkasho Reprocessing Plant), the high-level liquid waste concentrator is the equipment that treats the most corrosive solution. In the high-level liquid waste concentrator, the extracted liquid waste after separation of uranium and plutonium is heated, concentrated, and reduced in volume. Therefore, the amount of gamma- rays emitted from fission products and the concentration of corrosive metal ion species such as neptunium-237 (
Np) are the highest in the reprocessing process, and the amount of corrosion in the high-level liquid waste concentrate canner is expected to be large. In this study, in order to clarify the effect of gamma-rays on the corrosion reaction of stainless steel in nitric acid solutions containing Np from the electrochemical viewpoint, the corrosion test apparatus for heat transfer surfaces in an airtight concrete cell at the Waste Safety TEsting Facility (WASTEF) of Nuclear Science Research Institute was modified to enable electrochemical measurements under gamma-ray irradiation. The effect of gamma-rays on the corrosion reaction taking place on the stainless steel surface was discussed from the electrochemical test results obtained. As a result, changes in the immersion potentials of stainless steel and the polarization curves due to chemical species caused by radiolysis of gamma-ray irradiation were confirmed.
Sano, Naruto; Yamashita, Naoki; Hoshino, Kazutoyo*; Tsukada, Manabu*; Sawauchi, Fumiya*; Otake, Yoshinori; Ichise, Kenichi; Tagami, Susumu
JAEA-Technology 2022-034, 47 Pages, 2023/03
JAEA-Technology-2022-034.pdf:2.81MB
The Waste Safety Testing Facility (WASTEF) was established in 1982 as an experimental facility for long-term storage of solidified high-level radioactive waste generated in the reprocessing of spent light water reactor fuel and the subsequent safety assessment of geological disposal. It is a historic facility that started operation in 1982. This facility consists of 5 concrete cells, 1 lead cell, 6 glove boxes, and 7 hoods, and is a large-scale facility that can use nuclear fuel materials including uranium and plutonium and radioactive isotopes including TRU. In this facility, research and development requested by the research department is carried out in the Hot Material Examination Section. In addition, patrol inspections, self-inspections, etc. are also carried out as maintenance management based on safety regulations. This report summarizes the overview of WASTEF facilities, the results of operation, maintenance and management work in FY2021, and the future outlook.
Sr dissolved solution on corrosion potential of type 316L stainless steelAoyama, Takahito; Kato, Chiaki; Sato, Tomonori; Sano, Naruto; Yamashita, Naoki; Ueno, Fumiyoshi
Zairyo To Kankyo, 71(4), p.110 - 115, 2022/04
no abstracts in English
NpIrisawa, Eriko; Kato, Chiaki; Yamashita, Naoki; Sano, Naruto
Zairyo To Kankyo, 71(3), p.70 - 74, 2022/03
In order to evaluate the corrosion of stainless steels used in spent nuclear fuel reprocessing facilities, the immersion corrosion tests and polarization measurements were performed using R-SUS304ULC stainless steel in nitric acid solution containing a kind of radionuclides, Np. At temperatures above 328 K, the corrosion potential was higher than that in nitric acid solution and was near the transpassive region. From the comparison between the corrosion amount calculated by the immersion corrosion tests and the polarization resistance, the values of 
=0.018-0.025 V were obtained as a conversion factor, and the possibility of calculating the corrosion amount from the electrochemical measurement was examined.
Tagami, Susumu; Shimizu, Osamu; Sano, Naruto; Imaizumi, Akiko; Tobita, Hiroshi; Nagasaki, Yosuke; Kurobane, Shiro
JAEA-Review 2010-079, 90 Pages, 2011/03
JAEA-Review-2010-079.pdf:3.02MB
The Back-end Cycle Key Elements Research Facility (BECKY) was installed in the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) in 1994 for the safety and basic studies of the nuclear fuel cycle and radioactive waste. BECKY consists of three alpha/
concrete cells, three alpha/ steel cells, thirty glove boxes and twenty hoods. Operation, maintenance and management are in execution based on the operational safety programs. And we also execute application about amendment of the permission and approval for the purpose of support R&D. This report describes the operation, maintenance and management from April 1, 2005 to March 31, 2010 for the purpose of keeping the performance of BECKY.
Tagami, Susumu; Sano, Naruto; Otobe, Haruyoshi; Akabori, Mitsuo; Kurobane, Shiro
JAEA-Technology 2010-034, 65 Pages, 2010/10
JAEA-Technology-2010-034.pdf:3.56MB
An experimental facility called the Module for TRU High Temperature Chemistry (TRU-HITEC) was installed in the Back-end Cycle Key Elements Research Facility (BECKY) of the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) in February, 2003. The main purpose of this facility is to perform the basic studies of the behavior the transuranium elements (TRU) in pyrochemical reprocessing and oxide fuels. Hot-experiment started in December, 2004. TRU-HITEC consists of three 
/ cells and a glove box. This is the only facility in the country as large-scale facilities maintained a high purity argon gas atmosphere. The experience gained through the maintenance and improvement is useful also for the maintenance of similar designed facility. This report describes the maintenance method and improvement for the purpose of keeping the performance of TRU-HITEC.
Terunuma, Hirotaka; Tanaka, Kiwamu; Kabumoto, Hiroshi; Haginoya, Masashi; Sano, Naruto; Takahashi, Masatomi; Hoshino, Masato; Aoki, Isao; Asazuma, Shinichiro
no journal, ,
no abstracts in English
Irisawa, Eriko; Yamashita, Naoki; Kato, Chiaki; Sano, Naruto
no journal, ,
In spent nuclear fuel reprocessing facilities, nitric acid solutions containing metal components derived from spent fuel are heated and concentrated. This process solution is highly corrosive to stainless steel. According to previous studies, it was shown that the dissolution of oxidizing metal ions causes the cathodic reaction to occur in a higher potential range than in pure nitric acid solutions. And, it has been suggested that the anodic reaction is not sensitive to dissolved metal ion species, but is determined by the concentration of acid nitrate chemical species such as HNO
and HNO
. On the other hand, the radiation released from the fuel-derived radionuclides can cause radiolysis of the reprocessing process solution. It is known that nitrous acid is produced by radiolysis of nitric acid media and reaction of nitric acid with radiolysis products. The formation of nitrite is thought to affect the anodic reaction among the corrosion reactions on the surface of stainless steels. In order to understand the corrosion reaction of stainless steel in reprocessing process solutions, it is necessary to evaluate the effect of gamma-rays on the anodic reaction of stainless steels in nitric acid media. In this study, the effect of gamma-rays on the corrosion potential and polarization curve of stainless steel in the nitric acid media was investigated. As a result, the increase in corrosion potential and the change in polarization curves were observed. And the causes of the obtained change of anodic polarization curves were verified from the results of nitrous acid addition and immersion time under non-irradiation.
Irisawa, Eriko; Yamashita, Naoki; Kato, Chiaki; Sano, Naruto
no journal, ,
In spent fuel reprocessing plants after nuclear power generation, intergranular corrosion of stainless steel components due to nitric acid solution containing metal ions derived from fuel is a problem. Although neptunium, a radioactive element, is considered to have a high contribution to corrosion, there have been few cases of systematic corrosion evaluations due to the difficulty of handling it. Therefore, the effects of solution temperature and neptunium ion concentration on the corrosion rate of stainless steel in nitric acid solution containing neptunium-237 were evaluated by immersion test and polarization measurement.
Irisawa, Eriko; Kato, Chiaki; Yamashita, Naoki; Sano, Naruto; Tagami, Susumu
no journal, ,
no abstracts in English
Saito, Shigeru; Wakui, Takashi; Tsukada, Manabu*; Yamashita, Naoki; Sano, Naruto; Dai, Y.*; Futakawa, Masatoshi
no journal, ,
Post irradiation examination (PIE) of the MEGAPIE (MEGAwatt Pilot Experiment) project has been performed on the samples allotted to JAEA. In the experiments, specimens for tensile test are prepared by taking from the component of the MEGAPIE target such as the beam window (BW) of T91. The irradiation temperatures were about 250 
C and the displacement-damage levels ranged between 0.75 and 1.74 dpa. After the tensile tests, SP specimens are prepared from the grip part of the tested tensile specimens. Testing temperatures for SP tests ranged from -150C to 250C. From the area of the load-displacement curves (LDC) of the SP tests, ductile-brittle transition temperature (DBTT) was evaluated. Comparison of these data with previous STIP data showed similar values. In addition, the yield stress and ultimate tensile strength were calculated from the SP tests results by applying the conversion equation. These were compared with the results of the tensile tests and found to be in good agreement.
Aoyama, Takahito; Sato, Tomonori; Ueno, Fumiyoshi; Kato, Chiaki; Sano, Naruto; Yamashita, Naoki; Igarashi, Takahiro
no journal, ,
no abstracts in English
Irisawa, Eriko; Kato, Chiaki; Yamashita, Naoki; Sano, Naruto; Tagami, Susumu
no journal, ,
Aoyama, Takahito; Sato, Tomonori; Ueno, Fumiyoshi; Kato, Chiaki; Sano, Naruto; Yamashita, Naoki; Igarashi, Takahiro
no journal, ,
no abstracts in English
