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JAEA Reports

Summary of instructor training program in FY2014 aiming at Asian countries introducing nuclear technologies for peaceful use (Contract program)

Hidaka, Akihide; Nakano, Yoshihiro; Watanabe, Yoko; Arai, Nobuyoshi; Sawada, Makoto; Kanaizuka, Seiichi*; Katogi, Aki; Shimada, Mayuka*; Ishikawa, Tomomi*; Ebine, Masako*; et al.

JAEA-Review 2016-011, 208 Pages, 2016/07

JAEA-Review-2016-011-01.pdf:33.85MB
JAEA-Review-2016-011-02.pdf:27.68MB

JAEA has been conducting the Instructor Training Program (ITP) since 1996 under the auspices of MEXT to contribute to human resource development in currently 11 Asian countries in the field of radiation utilization for seeking peaceful use of nuclear energy. ITP consists of Instructor Training Course (ITC), Follow-up Training Course (FTC) and Nuclear Technology Seminars. In the ITP, trainings or seminars relating to technology for nuclear utilization are held in Japan by inviting nuclear related people from Asian countries to Japan and after that, the past trainees are supported during FTC by dispatching Japanese specialists to Asian countries. News Letter is also prepared to provide the broad range of information obtained through the trainings for local people near NPPs in Japan. The present report describes the activities of FY2014 ITP and future challenges for improving ITP more effectively.

JAEA Reports

On-site training using JMTR and related facilities in FY2015

Eguchi, Shohei; Takemoto, Noriyuki; Shibata, Hiroshi; Naka, Michihiro; Nakamura, Jinichi; Tanimoto, Masataka; Ito, Haruhiko*

JAEA-Review 2016-001, 31 Pages, 2016/05

JAEA-Review-2016-001.pdf:9.05MB

Since fiscal 2011, a practical training course using the JMTR and other research infrastructures has been provided by Neutron Irradiation Testing Reactor Center for foreign young researchers and engineers in Asian and other countries which are planning to introduce power reactors. The aim of this course is to contribute to the human resource development in nuclear research field and to increase the future use the JMTR. On the other hand, a training course for Japanese young researchers and engineers has been conducted since fiscal 2010. These two separate courses were integrated. In fiscal 2015, this training course was conducted for 2 weeks and 17 young researchers and engineers from 7 countries were participated. They studied about the general outline of nuclear research, current status and R&D about nuclear energy, safety management of nuclear reactor, irradiation behavior of materials and fuels, facilities and technologies for irradiation and post irradiation, and nuclear characteristics of the reactor through lectures and practical trainings. At the end of the course, we had a discussion about the current status and future of energy mix and renewable energies of each country was discussed. The content of this training course in fiscal 2015 is reported in this paper.

JAEA Reports

Performance test of ex-core high temperature and high pressure water loop test equipment (Contract research)

Nakano, Hiroko; Uehara, Toshiaki; Takeuchi, Tomoaki; Shibata, Hiroshi; Nakamura, Jinichi; Matsui, Yoshinori; Tsuchiya, Kunihiko

JAEA-Technology 2015-049, 61 Pages, 2016/03

JAEA-Technology-2015-049.pdf:14.7MB

In Japan Atomic Energy Agency, we started a research and development so as to monitor the Nuclear Plant Facilities situations during a severe accident, such as a radiation-resistant monitoring camera under a severe accident, a radiation resistant in-water transmission system for conveying the information in-core and a heat-resistant signal cable. As part of advance in a heat-resistant signal cable, we maintained to ex-core high-temperature and pressure water loop test equipment which can be simulated conditions of BWRs and PWRs for evaluation reliability and property of construction sheath materials. This equipment consists of Autoclave, water conditioning tank, water pump, high-pressure metering pump, preheater, heat exchanger and pure water purification equipment. This report describes the basic design and the results of performance tests of construction machinery and tools of ex-core high-temperature and pressure water loop test equipment.

JAEA Reports

On-site training using JMTR and related facilities in FY2014

Eguchi, Shohei; Takemoto, Noriyuki; Tanimoto, Masataka; Kubo, Ayako; Ishitsuka, Etsuo; Nakamura, Jinichi; Ito, Haruhiko

JAEA-Review 2015-005, 38 Pages, 2015/06

JAEA-Review-2015-005.pdf:15.06MB

Since fiscal 2011, a practical training course using the JMTR and other research infrastructures has been provided by Neutron Irradiation Testing Reactor Center for foreign young researchers and engineers in Asian and other countries which are planning to introduce power reactors. The aim of this course is to contribute to the human resource development in nuclear research field and to increase the future use the JMTR. On the other hand, a training course for Japanese young researchers and engineers has been conducted since fiscal 2010. In fiscal 2014, these two separate courses were integrated into one and it was conducted for 3 weeks for young researchers and engineers at home as well as abroad. Nineteen persons from seven countries participated and they studied about the general outline of nuclear research, current status and R&D of nuclear energy, irradiation test facilities and technologies, nuclear characteristics of the reactor and safety and operation management of nuclear reactors. At the end of the course, we had an active discussion about the current status and future of energy mix. The content of this training course in fiscal 2014 are reported in this paper.

JAEA Reports

2013 training using JMTR and related facilities as advanced research infrastructures

Takemoto, Noriyuki; Kimura, Nobuaki; Hanakawa, Hiroki; Shibata, Akira; Matsui, Yoshinori; Nakamura, Jinichi; Ishitsuka, Etsuo; Nakatsuka, Toru; Ito, Haruhiko

JAEA-Review 2013-058, 42 Pages, 2014/02

JAEA-Review-2013-058.pdf:4.95MB

Practical training courses using the JMTR and related facilities as an advanced research infrastructures have been carried out in Japan Atomic Energy Agency since FY2010 from a viewpoint of the nuclear human resource development and the securing. In FY2013, "Training course for foreign young researchers and engineers" was carried out from July 8th to July 26th, and "Training course using JMTR and related facilities as advanced research infrastructures" for domestic young researchers and engineers was carried out from July 29th to August 9th. 18 young researchers and engineers were joined in each training course, and 36 trainees in total studied about basic nuclear research and technology through the lecture and training about the reactor operation management, safety management, irradiation test, etc. in the JMTR. The results of these courses are reported in this paper.

Journal Articles

Development of instrumentation systems for safety measure at LWR's severe accident

Takeuchi, Tomoaki; Shibata, Akira; Nagata, Hiroshi; Kimura, Nobuaki; Otsuka, Noriaki; Saito, Takashi; Nakamura, Jinichi; Matsui, Yoshinori; Tsuchiya, Kunihiko

Proceedings of 3rd Asian Symposium on Material Testing Reactors (ASMTR 2013), p.52 - 58, 2013/11

In-pile instrumentation systems in present LWR's are indispensable to monitor all situations during reactor operation and reactor shut down. However, those systems did not work sufficiently under the conditions like as the severe accident at the Fukushima Dai-Ichi Nuclear Power Station. Therefore, based on the irradiation measurement technique of experiences accumulated in JMTR, the developments of reactor instrumentation systems to prevent severe core damage accident in advance have been started. The development objects are four instrumentation systems, which are a solid electrolysis type hydrogen concentration sensor, a water gauge of thermocouple type equipped with the heater, a $$gamma$$-ray detector of self-powered type SPGD, and an image analysis system of Cherenkov light for quantification of in-reactor information by CCD cameras. After the developments, the in-pile verification tests of four instrumentation systems are planned at the JMTR.

JAEA Reports

Development of heater-and-thermocouple-type water level sensor

Shibata, Akira; Miura, Kuniaki*; Takeuchi, Tomoaki; Otsuka, Noriaki; Nakamura, Jinichi; Tsuchiya, Kunihiko

JAEA-Technology 2013-024, 21 Pages, 2013/10

JAEA-Technology-2013-024.pdf:12.62MB

In the Fukushima-Daiichi Nuclear Power Plant Accident, the measurements of water level in pressure vessel and spent fuel pool were impossible due to station blackout, and it resulted in difficulty for countermeasures against the accidents and for understanding of the situations of reactor core after accidents. Therefore, we started to develop a new water level sensor for l with high reliability, which works with small electric power. This report describes reviews of conventional water level sensor and design and production of new water level sensor. After production of the sensor, performance tests were performed between room temperature and about 95 $$^{circ}$$C, and the it was confirmed that the sensor is able to measure water level with the accuracy of $$pm$$ 20 mm. As the results, a perspective to use the new water level sensor as water level indicator for spent fuel pools and reactor vessels after severe accident.

Journal Articles

Development of new in-pile instrumentation at JMTR

Shibata, Akira; Kimura, Nobuaki; Tanimoto, Masataka; Nakamura, Jinichi; Saito, Takashi; Tsuchiya, Kunihiko

JAEA-Conf 2012-002, p.56 - 60, 2012/12

To improve the quality of irradiation tests data and to increase the reliability of safety management system of reactors including both MTR and LWR, development of new instrumentation is key issue. JAEA is developing several in-pile instrumentations to conduct irradiation tests at JMTR. Here we introduce three new instrumentations. These are ECP sensor, new water level indicator and in-reactor observation system using Cherenkov light.

Journal Articles

Development of instruments for improved safety measure for LWRs

Takeuchi, Tomoaki; Shibata, Akira; Nagata, Hiroshi; Miura, Kuniaki*; Sano, Tadafumi*; Kimura, Nobuaki; Otsuka, Noriaki; Saito, Takashi; Nakamura, Jinichi; Tsuchiya, Kunihiko

Proceedings of 5th International Symposium on Material Testing Reactors (ISMTR-5) (Internet), 8 Pages, 2012/10

In-pile instrumentation systems in present LWR's are indispensable to monitor all situations during reactor operation and reactor shut down. However, those systems did not work sufficiently under the conditions of the severe accident at the Fukushima Dai-ichi (F1) Nuclear Power Plant. Based on instrumentation and irradiation experiences accumulated in JMTR, the developments of reactor instrumentation systems to prevent severe core damage accident in advance have been started. The development objects are water level gauge utilizing $$gamma$$ heating, self-powered $$gamma$$-ray detector, hydrogen concentration gauge, and analysis system for imaging and quantification of in-reactor information using Cherenkov light.

Journal Articles

Development of in-pile instruments for fuel and material irradiation tests

Shibata, Akira; Kitagishi, Shigeru; Kimura, Nobuaki; Saito, Takashi; Nakamura, Jinichi; Omi, Masao; Izumo, Hironobu; Tsuchiya, Kunihiko

JAEA-Conf 2011-003, p.185 - 188, 2012/03

To get measurement data with high accuracy for fuel and material behavior studies in irradiation tests, two kinds of measuring equipments have been developed; these are the Electrochemical Corrosion Potential (ECP) sensor, the Linear Voltage Differential Transformer (LVDT) type gas pressure gauge. The ECP sensor has been developed to determine the corrosive potential under high temperature and high pressure water condition. The structure of the joining parts was optimized to avoid stress concentration. The LVDT type gas pressure gauge has been developed to measure gas pressure in a fuel element during neutron irradiation. To perform stable measurements with high accuracy under high temperature, high pressure and high dosed environment, the coil material of LVDT was changed to MI cable. As a result of this development, the LVDT type gas pressure gauge showed high accuracy at 1.8% of a full scale, and good stability.

Journal Articles

Development of reactor water level sensor for extreme conditions

Miura, Kuniaki*; Shibata, Akira; Nakamura, Jinichi; Ogasawara, Toshihiko*; Saito, Takashi; Tsuchiya, Kunihiko

JAEA-Conf 2011-003, p.193 - 195, 2012/03

In the Fukushima accident, measurement failure of water level was one of the most important factors which caused this serious situation. The differential pressure type water level indicators are widely used in various place of nuclear plant but after the accident of TMI-2, the need of other reliable method has been demanded. And the BICOTH type and the TRICOTH type water level indicator for light water power reactors had been developed for in-pile water level indicator but currently those are not adopted to a nuclear power plant. In this study, the development of new type water level indicator which composed of thermocouple and heater, and the demonstration test and characteristic evaluation of the water level indicator were described.

Journal Articles

Fission gas release from high burnup mixed oxide (MOX) fuel pellets

Amaya, Masaki; Nakamura, Jinichi; Nagase, Fumihisa

Proceedings of Enlarged Halden Programme Group Meeting 2011 (CD-ROM), 12 Pages, 2011/10

Fission gas release (FGR) from the high burnup MOX fuel pellets was investigated by monitoring rod-internal pressure change during re-irradiation in the Halden reactor. At the first power ramp in the re-irradiation test, the internal pressures of the test rods abruptly increased when the fuel centre temperatures exceeded $$sim$$800$$^{circ}$$C, which was $$sim$$200$$^{circ}$$C lower than the 1% FGR threshold temperature expected from its burnup dependence in the low burnup region. The size of the pellet fragment which controls FGR in the test rod was evaluated based on the measured fractional FGR, and the results indicated that grain boundary tunnels and/or micro-cracks did not significantly form even after the increase of rod inner pressure was detected. This suggests that the abrupt FGR observed in the test rods was not due to the formation of grain boundary tunnels and/or micro-cracks, and the mechanism of FGR in the test rods differed from that in the low and middle burnup region.

Journal Articles

Thermal conductivity evaluation of high burnup mixed-oxide (MOX) fuel pellet

Amaya, Masaki; Nakamura, Jinichi; Nagase, Fumihisa; Fuketa, Toyoshi

Journal of Nuclear Materials, 414(2), p.303 - 308, 2011/07

 Times Cited Count:10 Percentile:31.54(Materials Science, Multidisciplinary)

In order to estimate the behavior of high burnup mixed-oxide (MOX) fuel, it is important to evaluate fuel temperature accurately. The thermal conductivity formula of MOX fuel pellet which is needed to evaluate the fuel temperature was proposed. By using Klemens's theory and reported thermal conductivities of unirradiated (U, Pu)O$$_{2}$$ and irradiated UO$$_{2}$$ pellets, the thermal conductivity formula which contains the effects of burnup and plutonium (Pu) addition was obtained. Temperature of high burnup MOX fuel was evaluated based on the above-mentioned formula and the thermal conductivity integral method, and was compared with the fuel temperatures measured in a test reactor. Since both values agreed well, it is considered that the proposed thermal conductivity formula of MOX pellets is adequate.

JAEA Reports

Establishment of experimental equipments in irradiation technology development building

Ishida, Takuya; Tanimoto, Masataka; Shibata, Akira; Kitagishi, Shigeru; Saito, Takashi; Omi, Masao; Nakamura, Jinichi; Tsuchiya, Kunihiko

JAEA-Testing 2011-001, 44 Pages, 2011/06

JAEA-Testing-2011-001.pdf:4.52MB

The Neutron Irradiation and Testing Reactor Center has developed new irradiation technologies to provide irradiation data with high technical value for the refurbishment and resume of the Japan Materials Testing Reactor (JMTR). For the purpose to perform assembling of capsules, materials tests, materials inspection and analysis of irradiation specimens for the development of irradiation capsules, improvement and maintenance of facilities were performed. The RI application development building was refurbished and maintained for above-mentioned purpose. After refurbishment, the building was named Irradiation Technology Development Building. It contains eight laboratories based on the purpose of use, and experimental apparatuses were installed. This report describes the refurbishment work of the RI application development building, the installation work and operation method of the experimental apparatuses and the basic management procedure of the Irradiation Technology Development Building.

Journal Articles

Development of instrumentation for international standard

Tanimoto, Masataka; Aoyama, Masashi; Kitagishi, Shigeru; Shibata, Akira; Saito, Takashi; Nakamura, Jinichi; Tsuchiya, Kunihiko

Proceedings of 1st Asian Symposium on Material Testing Reactors (ASMTR 2011), p.62 - 70, 2011/02

The new JMTR is expected to contribute to many fields: the lifetime extension of LWRs (aging management of LWRs, development of next generation LWRs, etc.), the expansion of industry use (production of the medical radioisotope $$^{rm 99m}$$Tc, etc.) and the progress of science and technology (namely, basic research on nuclear energy). To meet a wide range of users needs, new irradiation technologies with advanced techniques have been developed. In this paper, status of the development of new measuring instruments are introduced which for neutron and $$gamma$$ irradiation tests in JMTR such as multi-paired thermocouple, rod inner pressure gauge, Self-Powered Neutron Detector (SPND) and Self-Powered Gamma Detector (SPGD).

Journal Articles

Fuels and materials irradiation test plan at JMTR

Ise, Hideo; Ogiyanagi, Jin; Nakamura, Jinichi; Sasajima, Hideo; Takasa, Akira; Hanawa, Satoshi; Kawaguchi, Yoshihiko; Chimi, Yasuhiro; Nishiyama, Yutaka; Nakamura, Takehiko

FAPIG, (180), p.22 - 25, 2010/02

Refurbishment of Japan Materials Testing Reactor (JMTR) is conducted in Japan Atomic Energy Agency (JAEA) in order to solve irradiation related issues for safe long-term operation of current light water reactors (LWRs) and development of advanced LWRs. JMTR will restart its operation in FY 2011. Manufacturing and installation of the irradiation test facilities on safety research of fuels and materials are also in progress. The outline of the fuels and materials irradiation test plan is described in this report.

Journal Articles

Relationship between changes in the crystal lattice strain and thermal conductivity of high burnup UO$$_2$$ pellets

Amaya, Masaki; Nakamura, Jinichi; Fuketa, Toyoshi; Kosaka, Yuji*

Journal of Nuclear Materials, 396(1), p.32 - 42, 2010/01

 Times Cited Count:3 Percentile:72.46(Materials Science, Multidisciplinary)

Two kinds of disk-shaped UO$$_2$$ samples were irradiated in a test reactor up to about 60 and 130 GWd/t, respectively. The microstructures of the samples were investigated by means of optical microscopy, SEM/EPMA and micro-X-ray diffractometry. Thermal diffusivities of the irradiated samples were also measured and their thermal conductivities were evaluated. The thermal conductivity measurement results suggest that the amount of accumulated irradiation-induced defects depends on the irradiation condition of each sample. From the comparison of the changes in the lattice parameter and strain energy density before and after the thermal diffusivity measurements, it is likely that the thermal conductivity recovery in the temperature region from 1200 to 1500 K is related to the migration of dislocation.

Journal Articles

Thermal conductivity change in high burnup MOX fuel pellet

Nakamura, Jinichi; Amaya, Masaki; Nagase, Fumihisa; Fuketa, Toyoshi

Journal of Nuclear Science and Technology, 46(9), p.944 - 952, 2009/09

High burnup MOX and UO$$_{2}$$ test rods were prepared from the fuel rods irradiated in commercial BWRs. Each test rod was equipped with a fuel center thermocouple, and was re-irradiated in the Halden boiling water reactor (HBWR) in Norway. The burnups of MOX and UO$$_{2}$$ test rods reached about 84 GWd/tHM and 72 GWd/t, respectively. Thermal conductivity change in high burnup fuel was evaluated from the comparison between the measured fuel temperature and the data calculated by using the fuel analysis code, FEMAXI-6. The comparison results suggested that the thermal conductivity of MOX fuel pellet is comparable to that of UO$$_{2}$$ fuel pellet in the high burnup region around 80 GWd/t. It is probable that the impurity effect of Pu atom gradually diminishes with increasing burnup because other factors which affect pellet thermal conductivity, such as the accumulation effect of soluble fission products and irradiation-induced defects in crystal lattice, become dominant in high burnup region.

Journal Articles

Newly-designed capsules for fuel ramp tests in the JMTR

Hanawa, Satoshi; Ogiyanagi, Jin; Inaba, Yoshitomo; Sasajima, Hideo; Nakamura, Jinichi; Nakamura, Takehiko

Proceedings of Top Fuel 2009 (DVD-ROM), p.350 - 356, 2009/09

In order to perform power transient tests of new design LWR's fuels, new power transient test capsules, the natural convection capsule and the forced convection capsule, are being developed. The natural convection capsule has relatively simple structure, and the test fuel rod is cooled by the natural convection of the coolant. The basic technologies for the natural convection capsule have already been established and the power transient tests will be started by using this capsule. The forced convection capsule has relatively complicated structure for circulating the cooling water and controlling the cooling water temperature. By performing several mock-up test, we confirmed that the target linear heat rate is achievable by the capsules, and elemental technologies to realize the forced convection capsule is feasible.

Journal Articles

The Effects of irradiation condition and microstructural change on lattice parameter, crystal lattice strain and crystallite size in high burnup UO$$_{2}$$ pellet

Amaya, Masaki; Nakamura, Jinichi; Fuketa, Toyoshi

Journal of Nuclear Materials, 392(3), p.439 - 446, 2009/08

 Times Cited Count:5 Percentile:59.72(Materials Science, Multidisciplinary)

Pellet samples (average burnup: 37-62 GWd/t) were prepared from three kinds of fuel rods which were irradiated in the Halden Heavy Water Reactor in Norway, and microstructural changes in the pellet samples were investigated by means of optical microscopy, SEM/EPMA and micro-X-ray diffractometry. The measured lattice parameters tended to be smaller than the values reported previously, and it is likely that the measured lattice parameters were affected by the temperature conditions during the irradiation tests and the microstructural changes which occurred in the samples. Considering the burnup dependence of uniform and non-uniform strains, the following things are suggested: the interstitial atoms which cause uniform strain begin firstly to form dislocations as a recovery process of irradiation defect and the dislocation density increases. With increasing burnup, the accumulation of dislocations in the crystallite saturates and the migration of dislocations becomes dominant as a recovery process of irradiation defects in the crystallite.

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