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Journal Articles

Development of the residual sodium quantification method for a fuel pin bundle of SFRs before and after dry cleaning

Kudo, Hideyuki*; Otani, Yuichi*; Hara, Masahide*; Kato, Atsushi; Otaka, Masahiko; Ide, Akihiro*

Journal of Nuclear Science and Technology, 57(4), p.408 - 420, 2020/04

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In a fuel handling system of sodium-cooled fast reactors (SFRs), it is necessary to remove the sodium remaining on spent fuel assemblies (FAs) before storing them in a spent fuel water pool (SFP) in order to minimize plant operating loads. A next-generation SFR in Japan has adopted an advanced dry cleaning process which consists of the following steps, argon gas blowing to remove the metallic residual sodium on the FA, moist argon gas blowing to deactivate the residual sodium, and direct storage in the SFP. This three-step process increases economic competitiveness and reduces waste products thanks to a waterless process. In this R&D work, performance of the dry cleaning process has been investigated.

Journal Articles

Development of the residual sodium quantification method for a fuel assembly of SFRs

Kudo, Hideyuki*; Inuzuka, Taisuke*; Hara, Masahide*; Kato, Atsushi; Nagai, Keiichi; Ide, Akihiro*

Journal of Nuclear Science and Technology, 57(1), p.9 - 23, 2020/01

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In sodium-cooled fast reactors (SFRs), it is necessary to remove the sodium remaining on spent fuel assemblies (FAs) before storing them in a spent fuel water pool (SFP) in order to minimize plant operating loads. A next-generation SFR in Japan has adopted an advanced dry cleaning process which consists of the following steps: argon gas blowing to remove the metallic residual sodium on the FA, moist argon gas blowing to deactivate the residual sodium, and direct storage in the SFP. This process increases economic competitiveness and reduces waste products. In this RD work, performance of the dry cleaning process has been investigated. This paper describes experimental and analytical work focusing on the amount of residual sodium remaining on FA components, for instance the handling head, the wrapper tube, the upper shielding, and the entrance nozzle which was conducted after investigation of residual sodium on fuel pin bundles as a part of series study of the cleaning process.

Journal Articles

Dry cleaning process test for fuel assembly of fast reactor plant system, 1; Pilot scale test for fuel pin bundle

Kudo, Hideyuki*; Otani, Yuichi*; Hara, Masahide*; Kato, Atsushi; Ishikawa, Nobuyuki; Otaka, Masahiko; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki; Ide, Akihiro*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 10 Pages, 2019/05

A next generation SFR in Japan has adopted an advanced dry cleaning system which consists of the argon gas blowing process to reduce the amount of metallic residual sodium remaining on spent fuel assemblies. This paper describes experimental and analytical work focusing on the amount of residual sodium remaining on a fuel pin bundle before and after the argon gas blowing process. The experiments were conducted using a sodium test loop and a short specimen consisting of a 7 pin bundle. The effects of the blowing gas velocity and the blowing time were quantitatively analyzed in the experiments. On the basis of these experimental results, evaluation models predicting the amount of the residual sodium were constructed.

Journal Articles

Dry cleaning process test for fuel assembly of fast reactor plant system, 2; Laboratory scale test for fuel assembly and evaluation of the amount of residual sodium

Ide, Akihiro*; Kudo, Hideyuki*; Inuzuka, Taisuke*; Hara, Masahide*; Kato, Atsushi; Ishikawa, Nobuyuki; Otaka, Masahiko; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 10 Pages, 2019/05

A next generation SFR in Japan has adopted an advanced dry cleaning system which consists of the following process of argon gas blowing to reduce the amount of metallic sodium, moist argon gas blowing to deactivate the residual sodium, and direct storage in the SFP without using storage containers. This three-step process increases economic competitiveness and reduces waste products. In this Research and Development work, the amount of residual sodium and performance of the dry cleaning process were investigated. This paper describes experimental and analytical work for all parts of a fuel assembly except for a fuel pin bundle.

Journal Articles

ASTRID nuclear island design; Update in French-Japanese joint team development of decay heat removal systems

Hourcade, E.*; Mihara, Takatsugu; Dauphin, A.*; Dirat, J.-F.*; Ide, Akihiro*

Proceedings of 2018 International Congress on Advances in Nuclear Power Plants (ICAPP 2018) (CD-ROM), p.556 - 561, 2018/04

In the framework of the French-Japanese agreement signed in 2014, CEA, AREVA NP, JAEA, and MHI/MFBR is jointly performing components design of ASTRID such as Decay Heat Removal Systems (DHRS). This paper is giving an update concerning ASTRID DHR strategy with description of reference architecture evolution and project objectives. In particular, new developments were made for DHR during normal shutdown and role of Ex-Vessel system. A special focus is made on design process of automatic shutter to hydraulically connect Hot Plenum and cold plenum to enhance primary vessel natural convection.

Journal Articles

Dry cleaning process test for fuel assembly of fast reactor plant system

Kato, Atsushi; Nagai, Keiichi; Ara, Kuniaki; Otaka, Masahiko; Oka, Nobuki*; Tanaka, Masako*; Otani, Yuichi*; Ide, Akihiro*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 8 Pages, 2017/04

In a fuel handling system (FHS) of a sodium-cooled fast reactor, it is necessary to reduce residual sodium on a spent fuel subassembly before storing at a spent fuel water-pool (SFP) in order to minimize design loads. Although the wet cleaning process adopted on MONJU could eliminate almost all of residual sodium, a large amount of radioactive liquid waste occurs and it needs long duration of cleaning treatment and large plant commodities. On the other hand, Japan sodium-cooled fast reactor adopted an advanced dry cleaning system which consists of roughly blowing massive sodium on the fuel subassembly out by 300$$^{circ}$$C argon gas, inactivation of residual sodium to NaOH by moist argon gas and directly immersion into the SFP to achieve economic competitiveness and waste reduction. This paper reports current status of recent R&D activities to demonstrate a performance of the dry cleaning process in Japan which are for improvement of the cleaning performance and optimizing the FHS design.

Journal Articles

ASTRID nuclear island design; Advances in French-Japanese joint team development of decay heat removal systems

Hourcade, E.*; Curnier, F.*; Mihara, Takatsugu; Farges, B.*; Dirat, J.-F.*; Ide, Akihiro*

Proceedings of 2016 International Congress on Advances in Nuclear Power Plants (ICAPP 2016) (CD-ROM), p.1740 - 1745, 2016/04

In the framework of the French-Japanese agreement signed in 2014, CEA, AREVA NP, JAEA, and MHI/MFBR is jointly performing components design of ASTRID such as Decay Heat Removal Systems (DHRS). This paper is giving highlights of ASTRID DHRS current strategy. Focus is made on operating temperature diversification for in-vessel heat exchanger as well as core catcher coolability by an original features such as heat exchanger located within reactor cold pool, whose design was taken over by Japan team since 2014.

Journal Articles

Evaluation of external event effects on JSFR fuel handling system

Kato, Atsushi; Chikazawa, Yoshitaka; Uzawa, Masayuki*; Kaneko, Fumiaki*; Ide, Akihiro*

Nuclear Technology, 189(1), p.30 - 44, 2015/01

 Times Cited Count:1 Percentile:12.03(Nuclear Science & Technology)

Responding to the Fukushima Dai-ichi Nuclear Power Plant (1F-NPP) accident, robustness of the fuel handling system (FHS) in Japan sodium-cooled fast reactor (JSFR) against the earthquake and the tsunami is studied for 2010 design version. In the earthquake estimation, the margin of seismic resistance and the sloshing in Ex-vessel fuel storage tank (EVST) against the earthquake of the 1F-envelop condition was estimated. In terms of the tsunami evaluation, the scenario to lead fuel subassemblies into the stable cooling state and the potential of the cooling system are introduced in case of the loss of emergency power supply. As a result, it showed that JSFR FHS in the original design already had the potential to prevent the release of radioactive material. Additionally, some design improvements of the EVST cooling system was introduced.

Journal Articles

Velocity of entrainments formed by high velocity air jet flow in stagnant water

Akabane, Masaaki*; Koizumi, Yasuo; Uchibori, Akihiro; Kamide, Hideki; Ohshima, Hiroyuki

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 6 Pages, 2014/07

A liquid droplet entrainment which appears under heat transfer tube failure accident in a steam generator of sodium-cooled fast reactors and causes wastage on an adjacent tube was examined in this study. The visualization experiment on a high-pressure air jet in a liquid pool was carried out. Filament-like ears and wisps pulled out from the wavy gas-liquid interface were observed. The ears and the wisps were broken off and entrained into the air jet. This process seems quite similar to the entrainment process in an annular dispersed flow in a pipe. The velocity of the entrained droplet was estimated from an image processing. The axial velocity of the entrained droplet increased as the air jet velocity increased. The Transversal directional velocity was much slower than the axial directional velocity. The data obtained from this experiment are very useful for the study of the heat transfer tube failure accident.

Journal Articles

Magnetic patterning of FeRh thin films by energetic light ion microbeam irradiation

Koide, Tetsuya*; Sato, Takahiro; Koka, Masashi; Saito, Yuichi; Kamiya, Tomihiro; Okochi, Takuo*; Kotsugi, Masato*; Kinoshita, Toyohiko*; Nakamura, Tetsuya*; Iwase, Akihiro*; et al.

Japanese Journal of Applied Physics, 53(5S1), p.05FC06_1 - 05FC06_4, 2014/05

 Times Cited Count:9 Percentile:43.85(Physics, Applied)

We previously reported that the magnetic state of FeRh can be controlled by irradiation with ion beams. In this paper, we evaluate possibility of magnetic patterning on FeRh thin films using energetic light ion microbeam irradiation with various shapes and dimensions. Proton microbeam irradiation with 2 MeV was performed at JAEA-Takasaki to produce micron-sized magnetic patterns. XMCD-PEEM observation was performed at SPring8 to confirm the synthesized magnetic patterns. As a result, the XMCD-PEEM images of the various micrometer sized patters in FeRh film were observed using 2 MeV H ion beam. The observed bright regions are considered to have ferromagnetic spin orders, in contrast that the gray areas have anti-ferromagnetic spin order. Since the brightness of the PEEM images is strongly correlated with the magnetization of the samples, we reveal that the magnetic state in local regions of the FeRh thin films can be controlled by changing the ion fluences.

Journal Articles

Progress of design study on fuel handling system in JSFR against design extension conditions

Otaka, Masahiko; Kato, Atsushi; Chikazawa, Yoshitaka; Uzawa, Masayuki*; Ide, Akihiro*; Kaneko, Fumiaki*; Hara, Hiroyuki*

Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.607 - 615, 2014/04

Responding to the TEPCO's Fukushima Dai-ichi Nuclear Power Station accident, the design study was carried out to enhance cooling function of fuel handling system for Japan sodium-cooled fast reactor (JSFR). Design measures to maintain an FHS cooling function even in case of Design Extension Conditions are studied; such as alternative cooling systems which are independent and diversified from design basis cooling systems. Based on effectiveness evaluations, it was confirmed that these measures have adequate availability against the postulated design extension conditions.

Journal Articles

Entrainment into high speed air jet blowing out from a hole to stagnant water

Koizumi, Yasuo*; Nago, Kohei*; Uchibori, Akihiro; Kamide, Hideki; Ohshima, Hiroyuki

Proceedings of ASME 2013 International Mechanical Engineering Congress and Exposition (IMECE 2013) (DVD-ROM), 6 Pages, 2013/11

Flow visualization experiments of an air jet in liquid were performed. The air jet was blown vertically upward into stagnant water or kerosine in the test vessel from a 1 mm width nozzle which was located at the bottom of the test vessel. A flow state of the jet in the liquid was recorded with a high speed video camera. Experimental result showed that the filament-like ears and wisps were pulled out from the wavy interface between liquid and the air jet. The ears and wisps were broken off and entrained into the air jet. As the air jet velocity increased, the number of entrainments created by the air jet increased lineally. The correlation for the entrainment diameter distribution which was developed for the annular dispersed two-phase flow in a pipe predicted well the present results. Measured entrainment rates were considerably lower than the prediction of the correlation for the annular dispersed two-phase flow in a pipe.

Journal Articles

Spin orientation transition across the single-layer graphene/nickel thin film interface

Matsumoto, Yoshihiro; Entani, Shiro; Koide, Akihiro*; Otomo, Manabu; Avramov, P.; Naramoto, Hiroshi*; Amemiya, Kenta*; Fujikawa, Takashi*; Sakai, Seiji

Journal of Materials Chemistry C, 1(35), p.5533 - 5537, 2013/09

 Times Cited Count:22 Percentile:71.5(Materials Science, Multidisciplinary)

Journal Articles

Local structures and magnetic properties of fullerene-Co systems studied by XAFS and XMCD analyses

Hojo, Ikuko*; Koide, Akihiro*; Matsumoto, Yoshihiro; Maruyama, Takashi*; Nagamatsu, Shinichi*; Entani, Shiro; Sakai, Seiji; Fujikawa, Takashi*

Journal of Electron Spectroscopy and Related Phenomena, 185(1-2), p.32 - 38, 2012/03

 Times Cited Count:1 Percentile:8.37(Spectroscopy)

Journal Articles

Investigation on integrity of JMTR reactor pressure vessel

Ide, Hiroshi; Kimura, Akihiro; Miura, Hiroshi; Nagao, Yoshiharu; Hori, Naohiko; Kaminaga, Masanori

Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM), 10 Pages, 2010/05

Visual observation of inner side of a reactor pressure vessel (RPV) of JMTR was carried out using an underwater camera before the JMTR refurbishment work, because the RPV of the JMTR will be used continuously after restart of the JMTR. As a result of the visual observation, the harmful wound was not confirmed. Moreover, there was no loosening of the bolts and the screws. On the other hand, adhesion materials which can be easily removed were observed in a top closure. A major component of the adhesion materials is an iron as a result of the componential analysis. However, no significant problem affecting the integrity of the RPV was observed, and then the integrity of the RPV was confirmed. From view points of the stress corrosion cracking, fast neutron fluence and fatigue, it became clear that the RPV of the JMTR can be used for more than 20 years. The visual observation by the underwater camera is to be carried out periodically to confirm the integrity of the RPV in future.

Journal Articles

The Progress of R&Ds for JSFR innovative technologies

Kikuchi, Hirohiko*; Mochida, Haruo*; Ide, Akihiro*; Iitsuka, Toru*; Hayafune, Hiroki

Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM), 10 Pages, 2010/05

Journal Articles

Numerical study on passive control of thermal striping phenomenon using Lorentz force in fast reactor

Takata, Takashi*; Fukuda, Takeshi*; Yamaguchi, Akira; Uchibori, Akihiro; Kimura, Nobuyuki; Kamide, Hideki

Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM), 7 Pages, 2010/05

Liquid sodium, used as a coolant of fast reactor (FR), is an electromagnetic fluid. When a magnetic field is embedded to liquid sodium flow, the Lorentz force will be induced and flow structure such as a turbulent mixing phenomenon will be influenced. In a FR piping system, thermal fatigue is one of key issues that may be occurred after a piping junction of different fluid temperature. In the present paper, a numerical study of sodium flow induced by the Lorentz force on a turbulent mixing after the junction has been carried out. The large eddy simulation (LES) coupled with the electromagnetic field analysis is used for this purpose. The numerical results showed that the temperature fluctuation due to turbulent mixing weakens after it runs through the magnetic field caused by the Lorentz force and thus the thermal fatigue will be suppressed. Accordingly, it is concluded that the passive control of the thermal fatigue will be possible by adding the magnetic field.

JAEA Reports

Inner side visual inspection of JMTR reactor pressure vessel

Ide, Hiroshi; Kimura, Akihiro; Miura, Hiroshi; Hori, Naohiko; Nagao, Yoshiharu

JAEA-Technology 2009-067, 39 Pages, 2010/02

JAEA-Technology-2009-067.pdf:13.1MB

Visual inspection of inner side of a reactor pressure vessel was carried out using a underwater camera before the JMTR refurbishment work from the view point of its long term utilization because the reactor pressure vessel of the JMTR will be used continuously after restart of the JMTR. As a result, adhesion materials which can be easily removed using the gauze were observed around nozzles in a top head of the reactor pressure vessel. A major component of the adhesion materials is an iron as a result of the componential analysis. However, no significant problem affecting the integrity of the reactor pressure vessel was observed, and thus the integrity of the reactor pressure vessel was confirmed. As for the view point of the aged effect, it became clear that the reactor pressure vessel of the JMTR can be used for more than 20 years. The visual inspection by the underwater camera is to be carried out periodically to confirm the integrity of the reactor pressure vessel.

Journal Articles

Correlation between initial deformation ratio of convergence and lining stress in shaft excavation

Yamazaki, Masanao; Tsusaka, Kimikazu; Hatsuyama, Yoshihiro*; Minamide, Masashi*; Takahashi, Akihiro*

Dai-38-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM), p.196 - 201, 2009/01

The Underground Research Laboratory in Hokkaido has been constructed by JAEA. In shaft excavation, convergence, lining stress, etc. are measured and analyzed in order to evaluate the validity of a support design. In this report, correlation between initial deformation ratio of convergence and lining stress in shaft excavation is discussed. Prediction equation of the lining stress from the initial deformation ratio of convergence in the short step method is also proposed.

JAEA Reports

Description of "Design guideline for gas entrainment prevention using CFD method" (Cooperative research)

Ohshima, Hiroyuki; Sakai, Takaaki; Kamide, Hideki; Kimura, Nobuyuki; Ezure, Toshiki; Uchibori, Akihiro; Ito, Kei; Kunugi, Tomoaki*; Okamoto, Koji*; Tanaka, Nobuatsu*; et al.

JAEA-Research 2008-049, 44 Pages, 2008/06

JAEA-Research-2008-049.pdf:42.3MB

Japan Atomic Energy Agency has conducted a conceptional design study of a sodium-cooled fast reactor in a frame work of the FBR feasibility study. The plant system concept for a commercial step is intended to minimize a vessel diameter to achieve an economical competitiveness. Therefore, the coolant in the vessel has relatively higher velocity and gas entrainment (GE) prevention from a liquid surface in the reactor vessel becomes one of important issues for the thermal-hydraulic design. In order to establish a design criteria for the GE prevention, the GE from vortex dimples at the liquid surface was investigated by a working group. The 1st proposal of "Design Guideline for Gas Entrainment Prevention Using CFD Method" was established based on the knowledge gained from the working group activities. This report introduces each study in the working group to clarify the basis of the design guideline.

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