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Journal Articles

Estimation of mitigation effects of sodium nanofluid for SGTR accidents in SFR

Ichikawa, Kenta*; Kanda, Hironori; Yoshioka, Naoki*; Ara, Kuniaki; Saito, Junichi; Nagai, Keiichi

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 6 Pages, 2018/07

Studies on the suppression of the reactivity of sodium itself have been performed on the basis of the concept of suspended nanoparticles in liquid sodium (sodium nanofluid). According to the experimental and theoretical results of studies for sodium nanofluid, velocity and heat of sodium nanofluid-water reaction are lower than those of the pure sodium-water reaction. The analytical model for the peak temperature of a sodium nanofluid-water reaction jet has been developed in consideration of these suppression effects by the authors. In this paper, the prediction method for mitigation effects for a damage of adjacent tubes in a steam generator tube rupture (SGTR) accidents is arranged by applying this analytical model for the peak temperature of the reaction jet. On the assumption that the sodium nanofluid is used for the secondary coolant of sodium-cooled fast reactor (SFR), mitigation effects under the design-base accident (DBA) condition and the design-extension condition (DEC) of SGTR are estimated by using this method. As a result, there is a possibility to reduce the number of damaged tubes and to suppress the pressure generated by SGTR accidents by using sodium nanofluid in the secondary coolant.

Journal Articles

Study on chemical reactivity control of sodium by suspended nanoparticles, 1

Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Nagai, Masahiko*; Yoshioka, Naoki*

Journal of Nuclear Science and Technology, 47(12), p.1165 - 1170, 2010/12

 Times Cited Count:11 Percentile:63.66(Nuclear Science & Technology)

A study on the chemical reactivity control of sodium utilizing the atomic interaction of sodium with suspended nanoparticles was carried out. The atomic interaction between nanoparticles and sodium atoms were estimated by theoretical calculations and verified by fundamental physical properties measurements. Results showed the atomic bond of the sodium atom and the nanoparticle atom was significantly larger than that of the sodium atoms, when the transition metals that have the property of large electronegativity are applied as nanoparticles. From the theoretical calculation results, it was suggested that charge transfer occurs from the sodium atom to the nanoparticle atom. The fundamental physical properties of sodium with suspended nanoparticles were examined in comparison with that of sodium to verify the change of the atomic interaction. From the experimental results, it became clear that the surface tension becomes larger and the evaporation rate becomes smaller. These changes in fundamental physical properties were measured to verify the stability of the atomic interaction under the conditions of wide temperature range and the phase transformation from solid phase to liquid phase.

Journal Articles

Study on chemical reactivity control of sodium by suspended nanoparticles, 2

Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Nagai, Masahiko*; Yoshioka, Naoki*

Journal of Nuclear Science and Technology, 47(12), p.1171 - 1181, 2010/12

 Times Cited Count:10 Percentile:60.62(Nuclear Science & Technology)

A study was conducted on the control of the chemical reactivity of sodium utilizing the atomic interaction between sodium and nanoparticles. The authors reported in a previous paper that the atomic interaction between sodium and nanoparticles increases and has the potential to suppress chemical reactivity. In this paper, the authors examined the released reaction heat and the reaction behavior. As a result, it was confirmed that the released reaction heat and the reaction rate decreased. From the results of experimental studies, it is clear that the suppressions of chemical reactivity are caused by a change in the sodium evaporation rate and fundamental physical properties such as surface tension which originate in the change in the atomic interaction between sodium and nanoparticle atoms. The suppression of chemical reactivity applying to FBR coolant was estimated for the case of sodium combustion and sodium-water reaction. It was confirmed that the concept of suspending nanoparticles into sodium has high potential for the suppression of chemical reactivity. Applicability as coolant to the FBR was investigated, including not only the chemical reaction properties but also the aspects of heat transfer and operation.

Journal Articles

Thermal expansion of type A carbonate apatite

Tonegawa, Toru*; Ikoma, Toshiyuki*; Suetsugu, Yasushi*; Igawa, Naoki; Matsushita, Yoshitaka*; Yoshioka, Tomohiko*; Hanagata, Nobutaka*; Tanaka, Junzo*

Materials Science & Engineering B, 173(1-3), p.171 - 175, 2010/10

 Times Cited Count:10 Percentile:46.13(Materials Science, Multidisciplinary)

The thermal expansion and crystal structure of A-type carbonate apatite with the monoclinic symmetry was investigated using the neutron powder diffraction at room temperature, 200, 300, 400 and 500$$^{circ}$$C. The ${it a}$-axis and ${it c}$-axis lattice parameters were 0.9568 and 0.6868 nm at room temperature, and those were linearly increased with the increase of temperature. It was found that the linear thermal expansion coefficient of ${it a}$-axis was 1.31$$times$$10$$^{-5}$$/$$^{circ}$$C and ${it c}$-axis 8.07$$times$$10$$^{-6}$$/$$^{circ}$$C.

Journal Articles

Crystal structure of high purity type A carbonate apatite

Tonegawa, Toru*; Ikoma, Toshiyuki*; Suetsugu, Yasushi*; Igawa, Naoki; Matsushita, Yoshitaka*; Yoshioka, Tomohiko*; Hanagata, Nobutaka*; Tanaka, Junzo*

Proceedings of 22nd International Symposium on Ceramics in Medicine (BIOCERAMICS-22), p.93 - 96, 2009/12

Hydroxyapatite is the main inorganic component of bone and tooth minerals, in which CO$$_{3}$$ ions partially substitute for OH and/or PO$$_{4}$$ ions. In this study, high purity type A carbonate apatite, Ca$$_{9.89}$$(PO$$_{4}$$)$$_{5.99}$$(CO$$_{3}$$)$$_{0.90}$$ powder completely substituted by carbonate ions were synthesized by a treatment of low crystalline hydroxyapatite powder, Ca$$_{9.89}$$(PO$$_{4}$$)$$_{5.99}$$(OH)$$_{1.80}$$) in a dry CO$$_{2}$$ flow at 1000 $$^{circ}$$C. The crystal structure of the sample was the monoclinic symmetry with space group of ${it Pb}$ and the lattice parameters, ${it a}$ = 0.9566 (1), ${it b}$ = 1.9063 (2), ${it c}$ = 0.6867 (1) nm and $$gamma$$ =119.84 (1)$$^{circ}$$, which was refined by a Rietveld method with neutron diffraction data.

Journal Articles

Study on chemical reactivity control of liquid sodium; Development of nano-fluid and its property and applicability to FBR plant

Saito, Junichi; Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Nakano, Haruyuki*; Ogata, Kan*; Yoshioka, Naoki*

Proceedings of 16th International Conference on Nuclear Engineering (ICONE-16) (CD-ROM), 4 Pages, 2008/05

no abstracts in English

Journal Articles

Study on chemical reactivity control of liquid sodium; Research program

Saito, Junichi; Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Oka, Nobuki*; Yoshioka, Naoki*

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 5 Pages, 2007/04

Liquid sodium is used as the coolant of the fast breeder reactor (FBR), because of its high thermal conductivity and wide temperature range of liquid. However the chemical reactivity with water and oxygen of sodium is very high. So an innovative technology to control the reactivity is desired. The purpose of this study is to reduce the chemical reactivity of liquid sodium by dispersing the nanometer-size metallic particles into liquid sodium. Sub-themes of this study are nanoparticles production, evaluation of reaction control of liquid sodium, and feasibility study to FBR. In this paper, we describe the research program of them.

JAEA Reports

Study on the safety system in the High Temperature Gas Cooled Reactor (Contract research)

Nishihara, Tetsuo; Muto, Yasushi; Uchida, Shoji*; Yoshioka, Naoki*

JAERI-Tech 2001-077, 44 Pages, 2001/12

JAERI-Tech-2001-077.pdf:2.16MB

JAERI has conducted the feasibility study of the HTGR gas turbine system from 1996 to 2000 sponsored by MEXT. This report concludes the safety criteria and rationalization of the safety items in the HTGR system.With respect to the safety criteria, the same value for the LWR is selected as the limit of radiation exposure. Probability of the design basis event (DBE) and beyond design basis event (BDBE) is set lower than those for the LWR to get higher safety margin. Adequate initial events and mitigation system are selected to consider the event sequence. The concept of the probability analysis is applied to identify DBEs and BDBEs. It is found that some safety items can be rationalized in consideration of the safety features of the HTGR. Finally, the safety class and design category of the items in the HGTR-GT are classified.

Oral presentation

Study on chemical reactivity control of liquid sodium, 2; Progress and research program of elemental technology

Saito, Junichi; Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Yamauchi, Miho*; Yamashita, Akihiro*; Oka, Nobuki*; Yoshioka, Naoki*

no journal, , 

no abstracts in English

Oral presentation

Study on chemical reactivity control of liquid sodium, 1; Research program of project

Ara, Kuniaki; Saito, Junichi; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Ogata, Hiroshi*; Toda, Mikio*; Yoshioka, Naoki*

no journal, , 

no abstracts in English

Oral presentation

Study on chemical reactivity control of liquid sodium, 3; Preliminary feasibility study of nano-fluid to FBR plant

Ichikawa, Kenta*; Ara, Kuniaki; Saito, Junichi; Toda, Mikio*; Yoshioka, Naoki*

no journal, , 

no abstracts in English

Oral presentation

Development of core damage evaluation technology (level 2 PSA) for fast reactors, 1; Summary and scope

Niwa, Hajime; Kurisaka, Kenichi; Sato, Ikken; Tobita, Yoshiharu; Kamiyama, Kenji; Yamano, Hidemasa; Miyahara, Shinya; Ohno, Shuji; Seino, Hiroshi; Ishikawa, Hiroyasu; et al.

no journal, , 

In order to develop the core damage evaluation technology (level 2 PSA) for sodium-cooled fast reactors, we develop the new analysis codes of post accident material relocation phase and of ex-vessel events, and we develop the technical bases that is necessary for level 2 PSA. In this presentation, summary and scope of the entire study is introduced as a part of the 4 series presentations.

Oral presentation

Study on chemical reactivity control of liquid sodium, 6; Feasibility study of nano-fluid to FBR plant

Saito, Junichi; Konomura, Mamoru; Ara, Kuniaki; Toda, Mikio*; Yoshioka, Naoki*; Ichikawa, Kenta*

no journal, , 

no abstracts in English

Oral presentation

Development of core damage evaluation technology (level 2 PSA) for fast reactors, 5; Progress of R&D in FY2007

Nakai, Ryodai; Kurisaka, Kenichi; Sato, Ikken; Tobita, Yoshiharu; Kamiyama, Kenji; Yamano, Hidemasa; Miyahara, Shinya; Ohno, Shuji; Seino, Hiroshi; Ishikawa, Hiroyasu; et al.

no journal, , 

To develop a core damage evaluation technology (level-2 PSA) in sodium-cooled fast reactors, a new analysis method is developed for core-material relocation phase and internal containment vessel event. This study also develop technical basis necessary for the level-2 PSA.

Oral presentation

Study on chemical reactivity control of liquid sodium, 19; Evaluation on effect of application of nanofluid to FBR plant

Saito, Junichi; Yoshioka, Naoki*; Ichikawa, Kenta*; Oyama, Kazuhiro*; Toda, Mikio*; Ara, Kuniaki

no journal, , 

no abstracts in English

Oral presentation

Applicability of sodium with nanoparticles to FBR plant, 3; Confirmation of effect of application of nanofluid to FBR plant

Saito, Junichi; Ara, Kuniaki; Kanda, Hironori*; Yoshioka, Naoki*; Ide, Akihiro*; Matsumura, Atsushi*

no journal, , 

no abstracts in English

Oral presentation

Study on chemical reactivity suppression and coolant applicability of sodium with suspended nanoparticles

Saito, Junichi; Yoshioka, Naoki*; Nagai, Masahiko*; Ara, Kuniaki

no journal, , 

Oral presentation

Study on safety enhancement of the fast reactor by using nanoparticle suspension sodium, 1; Research plan

Ara, Kuniaki; Miyamoto, Akira*; Nagai, Masahiko*; Yoshioka, Naoki*

no journal, , 

no abstracts in English

Oral presentation

Study on a suppression of sodium-water reaction in SFR by applying sodium with suspended nanoparticles

Kanda, Hironori; Yoshioka, Naoki*; Ara, Kuniaki; Saito, Junichi; Nagai, Keiichi

no journal, , 

An important safety concern for SFR is the possibility of steam leaking from a tube at high-pressure into surrounding liquid sodium within the steam generator. The steam/liquid sodium pair is very reactive and the steam leak will form a sodium-water reaction jet which may attack and rupture adjacent tubes. A study on the suppression of the reactivity of sodium itself using the concept of suspended nanoparticles in liquid sodium (sodium nanofluid) has carried out. From the experimental results for sodium nanofluid, it was clear that the reaction rate and reaction heat with water were decreased by the atomic interaction of sodium with suspended nanoparticles. Taking the changes of physical and chemical property into account, an analytical model for peak temperature within a sodium nanofluid-water reaction jet has been constructed. The object of this paper is to confirm this analytical model for reaction jet temperature and to predict a mitigation effect on adjacent tube damage in a steam generator by applying sodium nanofluid to the secondary coolant of SFR. Comparing calculation results using the analytical model with the experimental results for a steam injection experiment, we demonstrated that the analytical model for temperature within the reaction jet is appropriate.

Oral presentation

A Study of measures against sodium-water reaction in next generation sodium-cooled fast reactor based on SDG

Kanda, Hironori; Enuma, Yasuhiro; Futagami, Satoshi; Chikazawa, Yoshitaka; Okano, Yasushi; Yoshioka, Naoki*; Ushiki, Hiroshi*

no journal, , 

Safety measures against sodium-water reaction have been discussed in Safety Design Guideline of GIF. In this study, redundancy and diversity of the design measures for steam generators were enhanced and consequences of multiple failures of the mitigation measures was assessed.

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