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Journal Articles

Application of JSME Seismic Code Case by elastic-plastic response analysis to practical piping system

Otani, Akihito*; Kai, Satoru*; Kaneko, Naoaki*; Watakabe, Tomoyoshi; Ando, Masanori; Tsukimori, Kazuyuki*

Proceedings of 2018 ASME Pressure Vessels and Piping Conference (PVP 2018), 10 Pages, 2018/07

This paper demonstrates an application result of the JSME Seismic Code Case to an actual complex piping system. The secondary coolant piping system of Japanese Fast Breeder Reactor, Monju, was selected as a representative of the complex piping systems. The elastic-plastic time history analysis for the piping system was performed and the piping system has been evaluated according to the JSME Seismic Code Case. The evaluation by the Code Case provides a reasonable result in terms of the piping fatigue evaluation that governs seismic integrity of piping systems.

Journal Articles

Proposal on LBB evaluation conditions for sodium cooled fast reactor pipes and effects of pipe parameters

Yada, Hiroki; Takaya, Shigeru; Wakai, Takashi; Nakai, Satoru; Machida, Hideo*

Nihon Kikai Gakkai Rombunshu (Internet), 84(859), p.17-00389_1 - 17-00389_15, 2018/03

no abstracts in English

Journal Articles

Current status and issues of sodium removal and disposal from LMFR in the framework of decommissioning

Nakai, Satoru

Dekomisshoningu Giho, (56), p.14 - 28, 2017/09

Prototype fast breeder reactor power plant Monju which is under construction was decided by the Japanese government not to operate but to be decommissioned safely and surely in December 2016. In the view point of decommissioning, one of the major difference from LWR is sodium as a coolant. In the overseas such as U.K., Germany, the United States, France, there is the precedent example of decommissioning and can be referred to it. In this report, the situation and problem of overseas example about removal and disposal of sodium.

Journal Articles

Maintenance

Nakai, Satoru

Fast Reactor System Design, p.249 - 267, 2017/03

The atomic energy plant has to maintain safety, reliability and structural integrity through plant life. Therefore, careful operation such as avoiding the thermal stress deviated from a design condition caused by a rapid temperature change is necessary. In addition, by the huge complexity system such as the nuclear power plant, a prediction of behavior during the life at the design stage is accompanied with uncertainty, and it is difficult to secure safety, reliability for a plant life only by a design. Therefore, appropriate maintenance activity is necessary, and consideration to the maintenance in the design stage relatively grows important. Particularly, the importance becomes still larger because uncertainty is big about the new type reactor. Therefore, I think that I want you to learn a way of thinking about the maintenance that is based on the characteristic of the fast reactor and basics of the maintenance of the nuclear power plant which is a huge complexity system.

Journal Articles

A Modelling study on water radiolysis for primary coolant in PWR

Mukai, Satoru*; Umehara, Ryuji*; Hanawa, Satoshi; Kasahara, Shigeki; Nishiyama, Yutaka

Proceedings of 20th International Conference on Water Chemistry of Nuclear Reactor Systems (NPC 2016) (USB Flash Drive), 9 Pages, 2016/10

In Japanese PWR, the concentration of dissolved hydrogen in the primary coolant is controlled in the range from 25 cc/kg-H$$_{2}$$O to 35 cc/kg-H$$_{2}$$O for suppression of water decomposition. However this concentration is desired to reduce for the purpose of radiation source reduction in Japan. So, the concentration due to water radiolysis in primary coolant was evaluated at lower hydrogen concentration by the water radiolysis model in consideration of $$gamma$$ ray, fast neutron and alpha ray due to the reaction $$^{10}$$B(n,$$alpha$$)$$^{7}$$Li. The results of evaluation showed that the water radiolysis was suppressed even if the hydrogen concentration was decreased to 5 cc/kg-H$$_{2}$$O. The effects of the different G-value and the rate constants of major reaction on the concentration of H$$_{2}$$O$$_{2}$$ and O$$_{2}$$ were studied under hydrogen addition. We also focused on the effect of the alpha radiolysis in boron acid water.

Journal Articles

Observation and evaluation of plastic collapse for double-notch pipe

Suzuki, Ryosuke*; Matsubara, Masaaki*; Sakamoto, Kenji*; Suzuki, Masato*; Shiraishi, Taisuke*; Yanagihara, Seiji*; Izawa, Satoru*; Wakai, Takashi

Experimental Techniques, 40(1), p.253 - 260, 2016/09

 Times Cited Count:0 Percentile:0.03(Engineering, Mechanical)

The plastic collapse behavior and strength were investigated for an austenitic stainless steel pipe with two 90$$^{circ}$$ through-wall notches perpendicular to the pipe axis direction. Double-notch specimens with various notch separation distances were coated with photo-plastic film. Arbitrary combined axial tensile and bending loads were applied to the specimens. Changes in the photo-plastic fringe pattern were observed during the tests to investigate the plastic collapse behavior. The plastic collapse strength was evaluated using a model based on an elastic-perfectly plastic body. The photo-plastic fringe patterns at the experimental plastic collapse point differed based on the loading history. Thus, the plastic collapse behavior depends on the loading history. In addition, the plastic collapse strength differed based on the loading history and hardly depended on the notch separation distance. The experimental plastic collapse occurred before reaching the theoretical plastic point for only some pure-tension loading tests. Thus, the model analysis based on an elastic-perfectly plastic body used in this study might give an unconservative estimate for the plastic collapse of a stainless steel pipe subjected to a pure tension load.

Journal Articles

Perturbation on hyperfine-enhanced $$^{141}$$Pr nuclear spin dynamics associated with antiferroquadrupolar order in PrV$$_2$$Al$$_{20}$$

Ito, Takashi; Higemoto, Wataru; Sakai, Akito*; Nakatsuji, Satoru*; Tsujimoto, Masaki*

Physical Review B, 92(12), p.125151_1 - 125151_5, 2015/09

 Times Cited Count:3 Percentile:17.86(Materials Science, Multidisciplinary)

JAEA Reports

Study on the evaluation method to determine the radioactivity concentration waste generated from post-irradiation examination facilities

Hoshino, Yuzuru; Sakamoto, Yoshiaki; Muroi, Masayuki*; Mukai, Satoru*

JAEA-Technology 2015-015, 96 Pages, 2015/07

JAEA-Technology-2015-015.pdf:20.34MB

In order to dispose of the radioactive waste which generates from post-irradiation examination (PIE) facilities, the common evaluation method of radioactivity in wastes from PIE should be established by the actual data such as radioactivity values and the theoretical calculation. In this study, the radioactivity concentrations of 17 nuclides (H-3, C-14, Co-60, Ni-63, Sr-90, Tc-99, Cs-137, Eu-154, U-234, U-235, U-238, Pu-238, Pu-239, Pu-240, Pu-241, Am-241, Cm-244) in combustible wastes stored in NUCLEAR DEVELOPMENT CORPORATION were measured from 3 samples and the radioactivity was calculated by ORIGEN-2 based on initial contents and operation record of the spent fuel. From the comparison of the obtained data by the radiological measurement with the calculated values, the subject to be solved for establishment of the radioactivity evaluation method for PIE was extracted.

Journal Articles

Application of the system based code concept to the determination of in-service inspection requirements

Takaya, Shigeru; Asayama, Tai; Kamishima, Yoshio*; Machida, Hideo*; Watanabe, Daigo*; Nakai, Satoru; Morishita, Masaki

Journal of Nuclear Engineering and Radiation Science, 1(1), p.011004_1 - 011004_9, 2015/01

A new process for determination of inservice inspection (ISI) requirements was proposed based on the System Based Code concept to realize effective and rational ISI by properly taking into account plant specific features. The proposed process consists of two complementary evaluations, one focusing on structural integrity and the other one on detectability of defects before they would grow to an unacceptable size in light of plant safety. If defect detection was not feasible, structural integrity evaluation would be required under sufficiently conservative hypothesis. The applicability of the proposed process was illustrated through an application to the existing prototype fast breeder reactor, Monju.

Journal Articles

Maintenance

Nakai, Satoru

Genshiryoku Kyokasho "Kosokuro Shisutemu Sekkei", p.199 - 214, 2014/09

The atomic energy plant has to maintain safety, reliability and structural integrity through plant life. Therefore, careful operation such as avoiding the thermal stress deviated from a design condition caused by a rapid temperature change is necessary. In addition, by the huge complexity system such as the nuclear power plant, a prediction of behavior during the life at the design stage is accompanied with uncertainty, and it is difficult to secure safety, reliability for a plant life only by a design. Therefore, appropriate maintenance activity is necessary, and consideration to the maintenance in the design stage relatively grows important. Particularly, the importance becomes still larger because uncertainty is big about the new type reactor. Therefore, I think that I want you to learn a way of thinking about the maintenance that is based on the characteristic of the fast reactor and basics of the maintenance of the nuclear power plant which is a huge complexity system.

Journal Articles

Application of maintenology to the fast reactor

Nakai, Satoru

Hozengaku, 13(2), p.41 - 42, 2014/07

The road map to establish a fast reactor (FR) maintenance technology in the technical aspect became clear in the examination of the FR maintenance in the Japan Society of Maintenology (JSM). It is vital to acquire operation and maintenance experience of the plant to implement this road map, and to establish a fast reactor maintenance technology. On the other hand, even if components to be maintained are defined and the maintenance methods are established, improvement of the maintenance ability in the organizations and individuals, proper and reliable implementation of the maintenance are indispensable. To improve the ability for maintenance, the action of the organized education, training and technical transmission is necessary including a light water reactor. The examination of the FR maintenance technology is a good opportunity for the application of the maintenance principles established by the JSM to the FR.

Journal Articles

Study on piping response under multiple excitation (validation for elastic-plastic analysis of piping)

Kai, Satoru*; Watakabe, Tomoyoshi; Kaneko, Naoaki*; Tochiki, Kunihiro*; Moriizumi, Makoto; Tsukimori, Kazuyuki

Proceedings of 2014 ASME Pressure Vessels and Piping Conference (PVP 2014) (DVD-ROM), 10 Pages, 2014/07

Piping in a nuclear power plant is usually laid across several floors of a single building or adjacent buildings, and is supported at many points. As the piping is excited by a large earthquake through multiple supporting points, seismic response analysis by multiple excitations within the range of plastic deformation of piping material is necessary to obtain the precise seismic response of the piping. This paper reports the validation results of the seismic elastic-plastic time history analysis of piping compared with the results of the shaking test of a 3-dimensional piping model under a plastic deformation range using triple uni-axial shake table.

Journal Articles

Study on piping response under multiple excitation; Validation for multiple excitation analysis of piping

Kai, Satoru*; Watakabe, Tomoyoshi; Kaneko, Naoaki*; Tochiki, Kunihiro*; Moriizumi, Makoto; Tsukimori, Kazuyuki

Dynamics and Design Conference 2013 (D&D 2013) Koen Rombunshu (USB Flash Drive), 10 Pages, 2013/08

The piping in a nuclear power plant is laid across multiple floors of a single building or multiple buildings which support the piping at many points. As the piping is excited by multiple-inputs from the supporting points during an earthquake, seismic response analysis by multiple excitations is needed to obtain the exact seismic response of the piping. However, only a few experiments involving such multiple excitations have been performed to verify the validity of multiple excitation analysis. To perform rational seismic design and evaluation, it is important to investigate the seismic response by multiple excitations and to verify the validity of the analytical method by multiple excitation tests. This paper reports the validation results of the multiple excitation analysis of piping compared with the results of the multiple excitations shaking test using triple uni-axial shaking table and a 3-dimensional piping model.

Journal Articles

Magnetic excitations and $$c$$-$$f$$ hybridization effect in PrTi$$_2$$Al$$_{20}$$ and PrV$$_2$$Al$$_{20}$$

Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Sakai, Akito*; Nakatsuji, Satoru*; Harima, Hisatomo*

Physical Review B, 88(8), p.085124_1 - 085124_7, 2013/08

 Times Cited Count:27 Percentile:77.13(Materials Science, Multidisciplinary)

By means of $$^{27}$$Al NMR studies, we have investigated magnetic excitations and the hybridization effect between Pr 4$$f$$ and conduction electrons in a pair of cubic compounds Pr$$Tr$$$$_2$$Al$$_{20}$$ ($$Tr$$=Ti, V). From Knight shift measurements we have evaluated comparative strengths for the $$c$$-$$f$$ hybridization effect in these compounds and confirm a definite increase of hybridization on replacing Ti with V. Analysis of the spin-lattice relaxation rate $$1/T_1$$ reveals that the spectral width of magnetic fluctuations in crystalline electric field excited states is strongly temperature dependent. This result indicates that magnetic fluctuations are dominated by the strong $$c$$-$$f$$ exchange coupling at high temperatures and thus is nicely consistent with the Kondo picture that features ln$$T$$ dependence of resistivity over the same temperature region.

Journal Articles

Study on piping response under multiple excitation, 2; Validation for multiple analysis of piping

Kai, Satoru*; Watakabe, Tomoyoshi; Kaneko, Naoaki*; Tochiki, Kunihiro*; Moriizumi, Makoto; Tsukimori, Kazuyuki

Proceedings of 2013 ASME Pressure Vessels and Piping Conference (PVP 2013) (DVD-ROM), 9 Pages, 2013/07

The piping in a nuclear power plant is laid across multiple floors of a single building or two buildings, which are supported at many points. As the piping is excited by multiple inputs from the supporting points during an earthquake, seismic response analysis by multiple excitations is needed to obtain the exact seismic response of the piping. However, few experiments involving such multiple excitations have been performed to verify the validity of multiple excitation analysis. To perform rational seismic design and evaluation, it is important to investigate the seismic response by multiple excitations and verify the validity of the analysis method by multiple excitation test. This paper reports the validation result of the multiple excitation analysis of piping compared with the results of the multiple excitations shaking test by using triple uni-axial shaking table and a 3-dimensional piping model (89.1 mm diameter and 5.5 mm thickness).

Journal Articles

Microscopic evidence for long-range magnetic ordering in the $$Gamma$$$$_{8}$$ ground quartet systems Sm$$Tr$$$$_{2}$$Al$$_{20}$$ ($$Tr$$: Ti, V, Cr)

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Sakai, Akito*; Nakatsuji, Satoru*

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB050_1 - SB050_4, 2012/12

Recently, $$RT_2$$Al$$_{20}$$ compounds ($$R$$: rare earth, $$T$$: transition metal) have attracted much attention due to interesting physical properties closely related to their caged-structure. Each $$R$$ ion is confined in a Frank-Kasper cage consisting of 16 Al atoms and the large coordination number leads to strong $$c$$-$$f$$ hybridization. In addition, the Frank-Kasper cage allows various multipole degrees of freedom for the $$f$$-electrons at low $$T$$ because of a highly symmetric crystalline-electric-field (CEF). Among the $$RT_2$$Al$$_{20}$$ series, Pr$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V) and Sm$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V, Cr) exhibit both these features. The $$Gamma_3$$ ground doublet systems Pr$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V) show a phase transition at $$T_O$$ = 2.0K (Ti) and 0.6K (V). The order parameter is believed to be an electric quadrupole active in the $$Gamma_3$$ subspace. A possibility of the quadrupole Kondo effect has been discussed based on characteristic $$T$$-dependence in specific heat, resistivity, and magnetic susceptibility. The $$Gamma_8$$ ground quartet systems Sm$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V, Cr) also exhibit a phase transition at $$T_O$$ = 6.4K (Ti), 2.3K (V), and 1.8K (Cr). A nuclear specific heat study in SmTi$$_2$$Al$$_{20}$$ suggests that the primary order parameter is a magnetic dipole in spite of field-insensitive nature of the phase boundary. A possible importance of a secondarily ordered octupole moment was discussed. We here present a microscopic study of PrTi$$_2$$Al$$_{20}$$ and Sm$$T_2$$Al$$_{20}$$ ($$T$$: Ti, V, Cr) using muon spin relaxation. In PrTi$$_2$$Al$$_{20}$$, no additional local field was observed in the ordered phase. This strongly supports the quadrupole ordering scenario. On the other hand, an appearance of a coherent local field was observed below $$T_O$$ in Sm$$T_2$$Al$$_{20}$$. This is consistent with the primary magnetic dipole ordering. The frequency distribution suggests that the magnetic structure is possibly different between the Sm$$T_2$$Al$$_{20}$$ compounds.

Journal Articles

Flux pinning properties of correlated pinning at low temperatures in ErBCO films with inclined columnar defects

Awaji, Satoshi*; Namba, Masashi*; Watanabe, Kazuo*; Kai, Hideki*; Mukaida, Masashi*; Okayasu, Satoru

Journal of Applied Physics, 111(1), p.013914_1 - 013914_4, 2012/01

 Times Cited Count:21 Percentile:67.04(Physics, Applied)

The effect of $$c$$-axis correlated pinning on the critical current density $$J$$$$_{c}$$ at low temperatures under high magnetic fields was investigated on the basis of the transport measurements of $$J$$$$_{c}$$ and irreversibility field B$$_{irr}$$ properties of an ErBa$$_{2}$$Cu$$_{3}$$O$$_{y}$$ film with inclined columnar defects. The contribution of correlated pinning on $$J$$$$_{c}$$ decreased drastically with decreasing temperature under high magnetic fields above the matching field. At low temperatures, the presence of a matching field limited the pinning force for correlated pinning, while the ratio of the maximum pinning force of the correlated pinning to the random one was proportional to the inverse of B$$_{irr}$$. In order to improve the critical current properties at low temperatures under high magnetic fields, an increase in the matching field and/or the introduction of strong random pinning are effective.

Journal Articles

$$mu$$SR evidence of nonmagnetic order and $$^{141}$$Pr hyperfine-enhanced nuclear magnetism in the cubic $$Gamma_3$$ ground doublet system PrTi$$_2$$Al$$_{20}$$

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Luetkens, H.*; Baines, C.*; Sakai, Akito*; Nakatsuji, Satoru*

Journal of the Physical Society of Japan, 80(11), p.113703_1 - 113703_4, 2011/11

 Times Cited Count:27 Percentile:79.19(Physics, Multidisciplinary)

Journal Articles

Event structure and double helicity asymmetry in jet production from polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 84(1), p.012006_1 - 012006_18, 2011/07

 Times Cited Count:25 Percentile:72.31(Astronomy & Astrophysics)

We report on the event structure and double helicity asymmetry ($$A_{LL}$$) of jet production in longitudinally polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. Photons and charged particles were measured by the PHENIX experiment. Event structure was compared with the results from PYTHIA event generator. The production rate of reconstructed jets is satisfactorily reproduced with the next-to-leading-order perturbative QCD calculation. We measured $$A_{LL}$$ = -0.0014 $$pm$$ 0.0037 at the lowest $$P_T$$ bin and -0.0181 $$pm$$ 0.0282 at the highest $$P_T$$ bin. The measured $$A_{LL}$$ is compared with the predictions that assume various $$Delta G(x)$$ distributions.

Journal Articles

Cooperative behavior of the random and correlated pinning in Er123 films with columnar defects

Awaji, Satoshi*; Namba, Masashi*; Watanabe, Kazuo*; Ito, Shun*; Aoyagi, Eiji*; Kai, Hideki*; Mukaida, Masashi*; Okayasu, Satoru

IEEE Transactions on Applied Superconductivity, 21(3), p.3192 - 3195, 2011/06

 Times Cited Count:5 Percentile:36.07(Engineering, Electrical & Electronic)

The flux pinning behaviors for the heavy ion irradiated Er123 films are investigated based on the detailed $$J$$$$_{rm c}$$ ($$B$$, $$T$$, $$theta$$) properties. The double peaks of $$F$$$$_{rm p}$$ curves for $$B$$//c appear in case of the matching field of 0.3 T along $$c$$-axis and 1.7 T tilted from $$c$$-axis. In addition, the peaks on $$J$$$$_{rm c}$$ ($$theta$$) at $$theta$$ = 0$$^{circ}$$ (B//c), which originate from the columnar defects, decrease with increasing magnetic field but increase again near the irreversibility field. We found that the cooperation model of the $$c$$-axis correlated and random pinning centers can describe the observed double peak behavior of $$F$$$$_{rm p}$$(B) and the angular dependence of $$J$$$$_{rm c}$$ related to the correlated pinning.

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