Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
O-induced oxidative degradation of simulated fuel debrisKumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Watanabe, Masayuki; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Sasaki, Takayuki*
Hoshasen Kagaku (Internet), (113), p.61 - 64, 2022/04
The severe accident at TEPCO's Fukushima Daiichi Nuclear Power Station resulted in generation of fuel debris. The fuel debris is in contact with water and the radiolysis of water can accelerate degradation of the debris. The analysis of particles sampled from inside or near the damaged reactors indicates the complicated compositions of the fuel debris. It is challenging to estimate the effect of water radiolysis on such a complicated material. Therefore, in this study, we investigated the potential degradation process by leaching experiments of simulated fuel debris in aqueous HO solution. The results show that the reaction of HO induced uranium dissolution from most of the samples and then formation of uranyl peroxides. In contrast, a sample that had U-Zr oxide solid solution as the major phase exhibited remarkable resistance to HO. These findings revealed that the degradation of the simulated debris reflects the reactivity and stability of the uranium phase in the matrices.
Ono, Ayato; Takayanagi, Tomohiro; Sugita, Moe; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu
JAEA-Technology 2021-044, 53 Pages, 2022/03
JAEA-Technology-2021-044.pdf:43.7MB
The 3-GeV rapid cycling synchrotron of Japan Proton Accelerator Research Complex (J-PARC) uses a large number of electromagnet power supplies in order to manipulate a high-intensity beam of 1 MW. These devices have been specially developed to meet the requirement to achieve acceleration of the 1-MW proton beams. Because J-PARC has been in operation for 10 years, we have to replace many parts and equipments due to failures caused by age-related deterioration. J-PARC accelerator system supplies the beams for many users, and we have to recover it as soon as possible when a trouble occurs. Therefore, if the trouble can be prevented before it happens, reduction of the user beam time can be minimized. Furthermore, it enables us to reduce additional work for operators. Maintenance is important to keep the equipments in a normal state, and makes it possible to extend the life of the equipments by detecting and maintaining the faulty parts and the aged deterioration parts at an early stage. Since all the devices requires the maintenance, there are a wide variety of maintenance methods. Some works are carried out by the J-PARC members, and some are performed by outsourcing. Ensuring safety and protecting workers are the most important issues in maintenance work. Therefore, J-PARC has rules for safety work. All workers in J-PARC have to learn and follow the rules. In addition, various ideas are being considered to enable safe and efficient work by devising ingenuity in each work. We also elaborate various ideas and processes for safe and efficient work according to the individual work conditions. In this report, we summarize the guideline and cautionary points during maintenance based on the actual case of maintenance and inspection work of the horizontal shift bump electromagnet power supply.
Miyazaki, Yasunori; Sano, Yuichi
Hoshasen Kagaku (Internet), (112), p.27 - 32, 2021/11
no abstracts in English
Yamaguchi, Yoshihito; Li, Y.
Haikan Gijutsu, 63(12), p.22 - 27, 2021/10
no abstracts in English
Yamaguchi, Yoshihito; Katsuyama, Jinya; Masaki, Koichi*; Li, Y.
Proceedings of ASME 2021 Pressure Vessels and Piping Conference (PVP 2021) (Internet), 9 Pages, 2021/07
The seismic probabilistic risk assessment is an important methodology to evaluate the seismic safety of nuclear power plants. In this assessment, the core damage frequency is evaluated from the seismic hazard, seismic fragilities, and accident sequence. Regarding the seismic fragility evaluation, the probabilistic fracture mechanics can be applied as a useful evaluation technique for aged piping systems with crack or wall thinning due to the age-related degradation mechanisms. In this study, to advance seismic probabilistic risk assessment methodology of nuclear power plants that have been in operation for a long time, a guideline on the seismic fragility evaluation of the typical aged piping systems of nuclear power plants has been developed considering the age-related degradation mechanisms. This paper provides an outline of the guideline and several examples of seismic fragility evaluation based on the guideline and utilizing the probabilistic fracture mechanics analysis code.
Miyazaki, Yasunori; Sano, Yuichi; Okamura, Nobuo; Watanabe, Masayuki; Koka, Masashi*
QST-M-29; QST Takasaki Annual Report 2019, P. 72, 2021/03
no abstracts in English
Yamaguchi, Yoshihito; Katsuyama, Jinya; Masaki, Koichi*; Li, Y.
JAEA-Research 2020-017, 80 Pages, 2021/02
JAEA-Research-2020-017.pdf:3.5MB
The seismic probabilistic risk assessment (seismic PRA) is an important methodology to evaluate the seismic safety of nuclear power plants. Regarding seismic fragility evaluations performed in the seismic PRA, the Probabilistic Fracture Mechanics (PFM) can be applied as a useful evaluation technique for aged piping with crack or wall thinning due to the age-related degradation. Here, to advance seismic PRA methodology for the long-term operated nuclear power plants, a guideline for the fragility evaluation on the typical aged piping of nuclear power plants has been developed taking the aged-related degradation into account.
Yamaguchi, Yoshihito; Mano, Akihiro; Katsuyama, Jinya; Masaki, Koichi*; Miyamoto, Yuhei*; Li, Y.
JAEA-Data/Code 2020-021, 176 Pages, 2021/02
JAEA-Data-Code-2020-021.pdf:5.26MB
In Japan Atomic Energy Agency, as a part of researches on the structural integrity assessment and seismic safety assessment of aged components in nuclear power plants, a probabilistic fracture mechanics (PFM) analysis code PASCAL-SP (PFM Analysis of Structural Components in Aging LWR - Stress Corrosion Cracking at Welded Joints of Piping) has been developed to evaluate failure probability of piping. The initial version was released in 2010, and after that, the evaluation targets have been expanded and analysis functions have been improved based on the state-of-the art technology. Now, it is released as Ver. 2.0. In the latest version, primary water stress corrosion cracking in the environment of Pressurized Water Reactor, nickel based alloy stress corrosion cracking in the environment of Boiling Water Reactor, and thermal embrittlement can be taken into account as target age-related degradation. Also, many analysis functions have been improved such as incorporations of the latest stress intensity factor solutions and uncertainty evaluation model of weld residual stress. Moreover, seismic fragility evaluation function has been developed by introducing evaluation methods including crack growth analysis model considering excessive cyclic loading due to large earthquake. Furthermore, confidence level evaluation function has been incorporated by considering the epistemic and aleatory uncertainties related to influence parameters in the probabilistic evaluation. This report provides the user's manual and analysis methodology of PASCAL-SP Ver. 2.0.
irradiationTakeuchi, Tomoaki; Otsuka, Noriaki; Uehara, Toshiaki; Kumahara, Hajime*; Tsuchiya, Kunihiko
QST-M-2; QST Takasaki Annual Report 2015, P. 80, 2017/03
no abstracts in English
Seguchi, Tadao*; Tamura, Kiyotoshi*; Kudo, Hisaaki*; Shimada, Akihiko; Sugimoto, Masaki
IEEE Transactions on Dielectrics and Electrical Insulation, 22(6), p.3197 - 3206, 2015/12
Times Cited Count：28 Percentile：76.71(Engineering, Electrical & Electronic)The degradation of ethylene propylene rubber (EPR) sheets as a cable insulation material for nuclear power plants (NPP) was studied by accelerated thermal ageing, radiation ageing and thermal - radiation combined ageing. The oxidation of EPR proceeded with ageing and the decay of mechanical property was closely related to the content of oxidation products. The antioxidant as a stabilizer in EPR was effective for the thermal oxidation, but not for the radiation oxidation. For the thermal and radiation combined oxidation, the mechanical property and the content of oxidation products were different among the treatment sequences due to the decay of antioxidant. The lifetime of EPR cable is closely related to the remaining content of antioxidant, and the lifetime evaluation would be recommended by the reverse sequential combination (thermal ageing after radiation ageing).
Futakawa, Masatoshi
IOP Conference Series; Materials Science and Engineering, 74(1), p.012001_1 - 012001_7, 2015/02
Times Cited Count：2 Percentile：65.6(Materials Science, Multidisciplinary)Innovative researches using neutrons are being performed at the Materials and Life Science Experimental Facility, MLF, at the Japan Proton Accelerator Research Complex, J-PARC, in which a mercury target system is installed for MW-class pulse spallation neutron sources. The structural materials of the mercury target are subjected to irradiation damage due to protons and neutrons, very high cycle fatigue damages due to repeated pressure waves caused by the proton beam bombardment in mercury and so-called liquid metal embrittlement. That is, the structural materials must be said to be exposed to the extremely severe environments. In the paper, research and development relating to the material issues in the high power spallation neutron sources that has been performed so far at J-PARC is summarized.
/p-AlInGaP solar cellsLee, H. S.*; Yamaguchi, Masafumi*; Ekins-Daukes, N. J.*; Khan, A.*; Takamoto, Tatsuya*; Imaizumi, Mitsuru*; Oshima, Takeshi; Ito, Hisayoshi
Physica B; Condensed Matter, 376-377, p.564 - 567, 2006/04
Times Cited Count：2 Percentile：12.58(Physics, Condensed Matter)no abstracts in English
Ueno, Fumiyoshi; Nagae, Yuji*; Nemoto, Yoshiyuki; Miwa, Yukio; Takaya, Shigeru*; Hoshiya, Taiji*; Tsukada, Takashi; Aoto, Kazumi*; Ishii, Toshimitsu; Omi, Masao; et al.
JAERI-Research 2005-023, 132 Pages, 2005/09
JAERI-Research-2005-023.pdf:33.03MB
JAERI and JNC have started a JAERI-JNC joint research program in fiscal year 2003, which has been aimed for efficient progress and synergistic effect on the research activities in both Institutes. This study has been chosen one of the joint research themes because it has been our common objective in the field of structural materials of FBR and LWR components. The purpose of the study is to clarify damage mechanism of structural materials used under irradiation, and then to develop the methods for damage evaluation and detection in earlier stage of progressing process of damage. In fiscal year 2004 and 2005, micro-corrosion measurement, electrochemical corrosion test and leakage magnetic flux density measurement apparatuses were developed and equipped in two hot facilities and irradiated and unirradiated crept specimens, irradiated high purity model austenitic stainless alloys were also prepared and applied to this study. These apparatuses and specimens were used for damage evaluation, and these feasibilities for nuclear power plant materials were studied.
Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka; Yagi, Toshiaki; Tamada, Masao
Journal of Nuclear Science and Technology, 42(7), p.636 - 642, 2005/07
Times Cited Count：20 Percentile：77.57(Nuclear Science & Technology)Radioactive durability of organic polymers in solid-polymer-electrolyte water electrolyzer was investigated by -ray irradiation. Serious deteriorations for tensile strength and ion exchange capacity of ion exchange membrane (Nafion) were not observed up to 850 kGy. No serious damage was also observed for the gasket materials (Aflas) up to 500 kGy. PFA and FEP, insulator materials, lost their tensile strength at 300 kGy or less. As the result, it is concluded that the electrolyzer could be used up to around 500 kGy in the case where PFA and FEP are replaced by the polyimide resin whose durability is well demonstrated. Two degrading mechanisms were supposed. One is direct degradation by energy of radial rays. The other is that by the attack of radicals. It was demonstrated that the effect of radicals on the membrane was not dominant. The quantity of dissolved fluorine in water was found to correlate with the tensile strength and ion exchange capacity. Hence, it is possible to evaluate the degradation of the membrane by monitoring the quantity of dissolved fluorine.
Sekimoto, Hiroshi*
JAERI-Tech 2005-008, 111 Pages, 2005/03
JAERI-Tech-2005-008.pdf:15.9MB
The CANDLE burnup strategy is a new reactor burnup concept, where the distributions of fuel nuclide densities, neutron flux, and power density move with the same constant speed from bottom to top (or from top to bottom) of the core and without any change in their shapes. Therefore, any burnup control mechanisms are not required, and reactor characteristics do not change along burnup. The reactor is simple and safe. When this burnup scheme is applied to some neutron rich fast reactors, either natural or depleted uranium can be utilized as fresh fuel after second core and the bunrup of discharged fuel is about 40%. It means that the nuclear energy can be utilized for many hundreds years without new mining, enrichment and reprocessing, and the amount of spent fuel can be reduced considerably. Compared to fast reactors, application of CANDLE burnup to prismatic fuel high-temperature gas cooled reactors is very easy. In this report, the applications of CANDLE burnup to both these types of reactors are studied.
Omori, Shunzo
Sangyo To Denki, (629), p.1 - 2, 2005/02
no abstracts in English
Oshima, Takeshi; Sumita, Taishi*; Imaizumi, Mitsuru*; Kawakita, Shiro*; Shimazaki, Kazunori*; Kuwajima, Saburo*; Oi, Akihiko*; Ito, Hisayoshi
Proceedings of 31st IEEE Photovoltaic Specialists Conference and Exhibition (PVSC-31), p.806 - 809, 2005/00
no abstracts in English
Sumita, Taishi*; Imaizumi, Mitsuru*; Oshima, Takeshi; Ito, Hisayoshi; Kuwajima, Saburo*
Proceedings of 31st IEEE Photovoltaic Specialists Conference and Exhibition (PVSC-31), p.667 - 670, 2005/00
no abstracts in English
Hoshiya, Taiji*; Ueno, Fumiyoshi; Takaya, Shigeru*; Nagae, Yuji*; Nemoto, Yoshiyuki; Miwa, Yukio; Aoto, Kazumi*; Tsukada, Takashi; Abe, Yasuhiro*; Nakamura, Yasuo*; et al.
JAERI-Research 2004-016, 53 Pages, 2004/10
JAERI-Research-2004-016.pdf:22.07MB
Japan Nuclear Cycle Development Institute (JNC) and Japan Atomic Energy Research Institute (JAERI) have started a JNC-JAERI united research program cooperatively in 2003, which has been aimed for efficient progress and synergistic effect on the research activities of both Institutes in order to lead the facing task of unification between JNC and JAERI. This study has been chosen one of the united research themes, and the purpose of it is to clarify damage mechanism of structural materials under irradiation, and then to develop the methods for damage evaluation and detection in earlier stage of progressing process of damage. In fiscal year 2003, magnetic flux density distribution (JNC) and micro-corrosion (JAERI) measurement apparatus were newly developed and equipped in Hot Facilities in two Institutes, respectively. These apparatus were designed and produced in consideration of radiation resistance and remote-controlled operation to equip in hot cells. We will start the study on neutron irradiation damage by employing the two apparatus as the next step.
Nakabayashi, Masakazu*; Oyama, Hidenori*; Hanano, N.*; Hirao, Toshio; Simoen, E.*; Claeys, C.*
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.183 - 186, 2004/10
no abstracts in English
