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Sugawara, Takanori; Takei, Hayanori; Tsujimoto, Kazufumi
Annals of Nuclear Energy, 125, p.242 - 248, 2019/03
Times Cited Count：2 Percentile：21.58(Nuclear Science & Technology)To realize the feasible accelerator-driven system (ADS) concept, the investigations for the reliable accelerator and conceptual plant design considering safety issues were performed. As the reliable accelerator concept, the double-accelerator concept was proposed to reduce the beam-trip frequency. The estimated beam-trip frequency with the double-accelerator concept using the J-PARC LINAC operation data showed that the beam-trip frequency was significantly improved with the comparison of the single accelerator result. The basic investigation of the primary reactor auxiliary coolant system (PRACS) was performed for the safety design of the LBE cooled ADS. The concept which the PRACS heat exchanger was integrated to the steam generator was proposed and the transient analysis in the loss of heat sink accident was carried out. The result presented that the decay heat removal was appropriate when the operation of the PRACS succeeded.
Saptiama, I.*; Kaneti, Y. V.*; Yuliarto, B.*; Kumada, Hiroaki*; Tsuchiya, Kunihiko; Fujita, Yoshitaka; Malgras, V.*; Fukumitsu, Nobuyoshi*; Sakae, Takeji*; Hatano, Kentaro*; et al.
Chemistry; A European Journal, 25(18), p.4843 - 4855, 2019/03
Times Cited Count：15 Percentile：55.35(Chemistry, Multidisciplinary)The effective utilization of various biomolecules for creating a series of mesoporous boehmite (
-AlOOH) and gamma-alumina (-Al
O
) nanosheets with unique hierarchical multilayered structures is demonstrated. The nature and concentration of the biomolecules strongly influence the degree of the crystallinity, the morphology, and the textural properties of the resulting -AlOOH and -AlO nanosheets, allowing for easy tuning. The hierarchical -AlOOH and -AlO multilayered nanosheets synthesized by using biomolecules exhibit enhanced crystallinity, improved particle separation, and well-defined multilayered structures compared to those obtained without biomolecules. More impressively, these -AlOOH and -AlO nanosheets possess high surface areas up to 425 and 371 m
/g, respectively, due to their mesoporous nature and hierarchical multilayered structure. When employed for molybdenum adsorption toward medical radioisotope production, the hierarchical -AlO multilayered nanosheets exhibit Mo adsorption capacities of 33.1
40.8mg-Mo/g.
Li, B.*; Kawakita, Yukinobu; Kawamura, Seiko; Sugahara, Takeshi*; Wang, H.*; Wang, J.*; Chen, Y.*; Kawaguchi, Saori*; Kawaguchi, Shogo*; Ohara, Koji*; et al.
Nature, 567(7749), p.506 - 510, 2019/03
Times Cited Count：182 Percentile：99.31(Multidisciplinary Sciences)Refrigeration is of vital importance for modern society for example, for food storage and air conditioning- and 25 to 30% of the world's electricity is consumed for refrigeration. Current refrigeration technology mostly involves the conventional vapour compression cycle, but the materials used in this technology are of growing environmental concern because of their large global warming potential. As a promising alternative, refrigeration technologies based on solid-state caloric effects have been attracting attention in recent decades. However, their application is restricted by the limited performance of current caloric materials, owing to small isothermal entropy changes and large driving magnetic fields. Here we report colossal barocaloric effects (CBCEs) (barocaloric effects are cooling effects of pressure-induced phase transitions) in a class of disordered solids called plastic crystals. The obtained entropy changes in a representative plastic crystal, neopentylglycol, are about 389 joules per kilogram per kelvin near room temperature. Pressure-dependent neutron scattering measurements reveal that CBCEs in plastic crystals can be attributed to the combination of extensive molecular orientational disorder, giant compressibility and highly anharmonic lattice dynamics of these materials. Our study establishes the microscopic mechanism of CBCEs in plastic crystals and paves the way to next-generation solid-state refrigeration technologies.
generation; The Role of NO
in the crevice corrosion repassivation of type 316L stainless steelAoyama, Takahito; Sugawara, Yu*; Muto, Izumi*; Hara, Nobuyoshi*
Journal of the Electrochemical Society, 166(10), p.C250 - C260, 2019/01
Times Cited Count：5 Percentile：17.1(Electrochemistry)The role of NO in the repassivation of crevice corrosion of Type 316L stainless steel was investigated. In crevice corrosion tests, the solution was changed from 1 M NaCl to NaCl-NaNO. NO led to complete repassivation. Repassivation of the crevice corrosion was found to take place in two steps. In the first step, the estimated current density inside the crevice gradually decreased from ca. 5 mA cm
to ca. 5 
A cm. After that, the current density suddenly decreased to less than 0.1 A cm. From the potentiodynamic polarization in acidic solutions simulated inside the crevice (pH 0.2) and in situ observations of the crevice corrosion morphology, the first step was thought to be generated by the suppression of active dissolution by NO
. It would appear that the generation of NH
results in a pH increase and the further suppression of active dissolution, and then repassivation occurs.
Sugawara, Takanori; Takei, Hayanori; Iwamoto, Hiroki; Oizumi, Akito; Nishihara, Kenji; Tsujimoto, Kazufumi
Progress in Nuclear Energy, 106, p.27 - 33, 2018/07
Times Cited Count：16 Percentile：85.18(Nuclear Science & Technology)The Japan Atomic Energy Agency (JAEA) has investigated an accelerator-driven system (ADS) to transmute minor actinides which will be partitioned from the high level waste. There are various inherent issues for the research and development on the ADS. The recent two activities to realize a feasible and reliable ADS concept are introduced in this paper. For the feasibility, the design of a beam window which is a boundary of the accelerator and the subcritical core, is one of the most important issues. To mitigate the design condition of the beam window, namely to reduce the proton beam current, the subcritical core concept with subcriticality adjustment rods were investigated. For the reliability, the beam-trip is the inherent and serious issue for the ADS design because it induces rapid temperature change to coolant and structures in the subcritical core. To improve the beam-trip frequencies, a double-accelerator concept was proposed and its beam-trip frequency was estimated.
Sugawara, Takanori; Nishihara, Kenji; Takei, Hayanori; Iwamoto, Hiroki; Oizumi, Akito; Sasa, Toshinobu; Tsujimoto, Kazufumi
Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.648 - 656, 2015/09
The JAEA has investigated an accelerator-driven system (ADS) to transmute minor actinides which will be partitioned from the high level waste. There are various inherent issues for the research and development on the ADS. This study introduces the current two activities to get a feasible and reliable ADS concept. For the feasibility, the beam window design is one of the most important issues. To mitigate the design condition of the beam window, namely to reduce the proton beam current, the subcritical core concepts with subcriticality adjustment mechanism were investigated. As the result, the proton beam current reduced from 20mA to 10mA by the installation of the control rods. For the reliability, the two accelerators concept was proposed and the beam trip frequency was estimated by the J-PARC LINAC data and Monte-Carlo method. Through these investigations, it was confirmed that the two accelerators concept was useful to realize reliable accelerator operation for the ADS.
SGo, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.
JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06
Sasa, Toshinobu; Takei, Hayanori; Saito, Shigeru; Obayashi, Hironari; Nishihara, Kenji; Sugawara, Takanori; Iwamoto, Hiroki; Yamaguchi, Kazushi; Tsujimoto, Kazufumi; Oigawa, Hiroyuki
NEA/CSNI/R(2015)2 (Internet), p.85 - 91, 2015/06
Nuclear transmutation got much interested as an effective option of nuclear waste management. Japan Atomic Energy Agency (JAEA) proposes the transmutation of minor actinides (MA) by accelerator-driven system (ADS) using lead-bismuth alloy (Pb-Bi). To obtain the data for ADS design, JAEA plans to build a Transmutation Experimental Facility (TEF) in the J-PARC project. TEF consists of two buildings, an ADS target test facility (TEF-T) with 400MeV-250kW Pb-Bi target, and a Transmutation Physics Experimental Facility (TEF-P), which set up a fast critical assembly driven by low power proton beam with MA fuel. In TEF-T, irradiation test for materials, and engineering tests for Pb-Bi target operation will be performed. Various research plans such as nuclear data measurements have been proposed and layout of the experimental hall are underway. In the presentation, roadmap to establish the ADS transmutor and latest design activities for TEF construction will be summarized.
Tsujimoto, Kazufumi; Nishihara, Kenji; Takei, Hayanori; Sugawara, Takanori; Iwamoto, Hiroki; Sasa, Toshinobu
NEA/NSC/R(2015)2 (Internet), p.254 - 261, 2015/06
The Japan Atomic Energy Agency (JAEA) has been conducting the research and development (R&D) on accelerator-driven system (ADS) as a dedicated transmutation system of long-lived radioactive nuclides. The ADS proposed by JAEA is a lead-bismuth eutectic (LBE) cooled fast subcritical reactor with thermal output of 800 MW. For ADS to play important roles in the nuclear fuel cycle, several critical issues have to be resolved. The critical issue in the design of the ADS is the engineering feasibility of the beam window for the high power spallation target. Although a feasible concept of the beam window for the ADS was proposed in our previous work. To mitigate the thermal load of the beam window not only in the normal operation but also in the transient situations, the R&D for the mechanism of reactivity adjustment and the accelerator design have been performed in JAEA.
P
; Evidence from resonant and nonresonant X-ray diffractionMatsumura, Takeshi*; Michimura, Shinji*; Inami, Toshiya; Hayashi, Yuya*; Fushiya, Kengo*; Matsuda, Tatsuma*; Higashinaka, Ryuji*; Aoki, Yuji*; Sugawara, Hitoshi*
Physical Review B, 89(16), p.161116_1 - 161116_5, 2014/04
Times Cited Count：15 Percentile：54.46(Materials Science, Multidisciplinary)The antiferromagnetic ordered phase below 
= 16.5 K and the unresolved intermediate phase between and 
(= 14 K) in SmRuP have been studied by resonant and nonresonant X-ray diffraction. In the intermediate phase, nonresonant Thomson scattering with 
= (1,0,0) is induced by applying a magnetic field. This phenomena is caused by atomic displacements reflecting the charge order in the 
band, as predicted theoretically. Simultaneously, the antiferromagnetic moment of Sm is enhanced along the field direction, which is considered to reflect the staggered ordering of the 
- 
crystal-field states. The present results show that the orbital-dependent - 
hybridization in association with the nesting instability in the band gives rise to the unconventional charge order similarly with PrRuP and PrFeP.
Tsujimoto, Kazufumi; Sasa, Toshinobu; Nishihara, Kenji; Sugawara, Takanori; Iwamoto, Hiroki; Takei, Hayanori
Proceedings of Joint IGORR 2014 & IAEA Technical Meeting (Internet), 10 Pages, 2014/00
Partitioning and Transmutation technology is expected to be effective to mitigate the burden of the HLW disposal. The Japan Atomic Energy Agency (JAEA) has been conducting the research and development (R&D) on accelerator-driven system (ADS) as a dedicated transmutation system of long-lived radioactive nuclides. For ADS to play important roles in the nuclear fuel cycle, several critical issues have to be resolved. To foster the R&D for most of above mentioned technical issues, JAEA plans to build the Transmutation Experimental Facility (TEF) which consists of two buildings: the Transmutation Physics Experimental Facility (TEF-P) and the ADS Target Test Facility (TEF-T). TEF-P is a zero-power critical facility which is operated with a low power proton beam to research the reactor physics and the controllability of ADS. Using this TEF-P facility, many experimental studies are planned.
Oigawa, Hiroyuki; Tsujimoto, Kazufumi; Sasa, Toshinobu; Kurata, Yuji; Takei, Hayanori; Saito, Shigeru; Nishihara, Kenji; Obayashi, Hironari; Sugawara, Takanori; Iwamoto, Hiroki
KURRI-KR(CD)-40 (CD-ROM), p.16 - 30, 2013/00
In JAEA, research and development on an Accelerator-Driven System (ADS) have been conducted in order to transmute minor actinides (MA) contained in high-level radioactive wastes. One unit of ADS with thermal power of 800 MW can transmute MA generated in 10 units of light water reactors with electric power of 1 GW. In JAEA, we are studying variety of technical areas such as a superconducting proton accelerator, a spallation target including a beam window and a subcritical core including neutronics design and safety assessment. Moreover, construction of the Transmutation Experimental Facility is being planned as a phase-2 program of the J-PARC project to perform basic experiments for transmutation technology.
Yoshikawa, Takehiro*; Sugawara, Shuichi*; Takayanagi, Toshiyuki*; Shiga, Motoyuki; Tachikawa, Masanori*
Chemical Physics, 394(1), p.46 - 51, 2012/02
Times Cited Count：18 Percentile：55.59(Chemistry, Physical)Path-integral molecular dynamics simulations have been performed for porphycene and its isotopic variants in order to understand the effect of isotopic substitution of inner protons on the double proton transfer mechanism. Our quantum simulations show that double proton transfer of the unsubstituted porphycene at the room temperature mainly occurs via a so-called concerted mechanism through the second-order saddle point. In addition, we found that both isotopic substitution and temperature significantly affect the double proton transfer mechanism. For example, the contribution of the stepwise mechanism increases with a temperature increase. It has been found that out-of-plane vibrational motions significantly decrease the contribution of the concerted proton transfer mechanism.
Tsujimoto, Kazufumi; Oigawa, Hiroyuki; Kurata, Yuji; Nishihara, Kenji; Sugawara, Takanori; Takei, Hayanori; Saito, Shigeru; Obayashi, Hironari; Iwamoto, Hiroki
Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 8 Pages, 2011/12
To continue the utilization of the nuclear fission energy, the management of the high-level radioactive waste (HLW) is one of the most important issues to be solved. Partitioning and Transmutation technology of HLW is expected to be effective to mitigate the burden of the HLW disposal by reducing the radiological toxicity and heat generation. The Japan Atomic Energy Agency (JAEA) has been conducting the research and development (R&D) on accelerator-driven subcritical system (ADS) as a dedicated system for the transmutation of long-lived radioactive nuclides. The ADS proposed by JAEA is a lead-bismuth eutectic (LBE) cooled fast subcritical reactor with thermal output of 800 MW. For ADS to play important roles in the nuclear fuel cycle, several critical issues have to be resolved. Items of R&D are divided into three technical areas peculiar to the ADS: (1) superconducting linear accelerator (SC-LINAC), (2) LBE as spallation target and core coolant, and (3) subcritical core design and technology. For these technical areas, various R&D activities are progressing in JAEA. In this paper, the present status of the R&D activities in JAEA is reported.
Sugawara, Shuichi*; Yoshikawa, Takehiro*; Takayanagi, Toshiyuki*; Shiga, Motoyuki; Tachikawa, Masanori*
Journal of Physical Chemistry A, 115(42), p.11486 - 11494, 2011/09
Times Cited Count：19 Percentile：56.05(Chemistry, Physical)We have carried out path integral molecular dynamics simulations for hydrated sulfuric acid clusters to understand acid-dissociation and hydrogen-bonded structural rearrangement processes in these clusters from a quantum mechanical viewpoint. We have found that the acid dissociation processes, first and second deprotonation, effectively occur in a hydrated cluster with a specific cluster size. The mechanisms of the proton-transfer processes were analyzed in detail and it was found that the distance between O in sulfuric acid and O in the proton-accepting water is playing an important role. We also found that the water coordination number of the proton-accepting water is important in the proton-transfer processes.
Oigawa, Hiroyuki; Tsujimoto, Kazufumi; Nishihara, Kenji; Sugawara, Takanori; Kurata, Yuji; Takei, Hayanori; Saito, Shigeru; Sasa, Toshinobu; Obayashi, Hironari
Journal of Nuclear Materials, 415(3), p.229 - 236, 2011/08
Times Cited Count：49 Percentile：95.87(Materials Science, Multidisciplinary)The Partitioning and Transmutation (P&T) technology provides the possibility to reduce the amount of the radiotoxic inventory of the high-level radioactive waste dramatically and to extend the repository capacity. The accelerator-driven system (ADS) is regarded as a powerful tool to effectively transmute minor actinides. The ADS has a potential to flexibly manage MA in the transient phase from light water reactors to fast breeder reactors (FBRs), and can co-exist with FBR symbiotically and complementarily to enhance the reliability and the safety of the commercial FBR cycle. The concept of ADS in JAEA is a lead-bismuth eutectic (LBE) cooled subcritical reactor. The design study was performed mainly for the subcritical reactor and the spallation target. In Japan, Atomic Energy Commission has implemented the check and review (C&R) on P&T technology from 2008 to 2009, and discussed the benefit of P&T technology, the current status of the R&D, and the way forward to promote it.
Yoshikawa, Takehiro*; Sugawara, Shuichi*; Takayanagi, Toshiyuki*; Shiga, Motoyuki; Tachikawa, Masanori*
Chemical Physics Letters, 496(1-3), p.14 - 19, 2010/08
Times Cited Count：27 Percentile：67.43(Chemistry, Physical)Full-dimensional path-integral molecular dynamics simulations were performed to determine whether the double proton transfer tautomerization of porphycene is a concerted or a stepwise process. It was found that double proton transfer occurs dominantly through the concerted pathway via the second-order saddle point structure and that contribution of the stepwise mechanism increases with a temperature increase. Nuclear quantum effects play essential roles in determining the proton transfer mechanism.
Tsujimoto, Kazufumi; Nishihara, Kenji; Takei, Hayanori; Sugawara, Takanori; Kurata, Yuji; Saito, Shigeru; Obayashi, Hironari; Sasa, Toshinobu; Kikuchi, Kenji*; Tezuka, Masao; et al.
JAEA-Research 2010-012, 59 Pages, 2010/07
JAEA-Research-2010-012.pdf:2.0MB
The design of an accelerator-driven system was modified and its feasibility was investigated on the basis of new data and knowledge for corrosion by lead-bismuth eutectic and irradiation behavior of candidate materials. The neutronics and thermal design was carried out and a modified core concept was established. As a result of evaluation for the integrity of fuel cladding tubes and a beam window, it was confirmed that their structural strength was sufficient under the conditions of design temperature and corrosion environment without irradiation. Though irradiation effects on material properties were considered not to be so serious under the practical conditions of the ADS according to existing irradiation data, it was needed to accumulate further experimental data for more detailed evaluation. According to level-1 PSA and dynamic analysis of beyond-design-basis accidents, it was shown that there was little possibility of core disruption and re-criticality accidents for ADS.
nucleus 
ArIdeguchi, Eiji*; Ota, Shinsuke*; Morikawa, Tsuneyasu*; Oshima, Masumi; Koizumi, Mitsuo; Toh, Yosuke; Kimura, Atsushi; Harada, Hideo; Furutaka, Kazuyoshi; Nakamura, Shoji; et al.
Physics Letters B, 686(1), p.18 - 22, 2010/03
Times Cited Count：36 Percentile：86.72(Astronomy & Astrophysics)A rotational band with five -ray transitions ranging from 2 to 12 states was identified in Ar. The deduced transition quadrupole moment of 1.45 
0.15 eb indicates that the band has a superdeformed shape. The nature of the band is revealed by cranked Hartee Fock Bogoliubov calculations and a multiparticle-multihole configuration is assigned to the band.
Sasa, Toshinobu; Sugawara, Takanori; Nishihara, Kenji; Takei, Hayanori; Oigawa, Hiroyuki
Proceedings of 10th OECD/NEA Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation (CD-ROM), p.349 - 356, 2010/00
Construction of the Transmutation Experimental Facility (TEF) is planned within the framework of J-PARC project. In the current schedule, we are planning to install the critical assembly with a 30kW beam dump at the first phase and the lead-bismuth target facility with superconducting LINAC will be built at the latter phase. Based on this construction plan, JAEA collected the preliminary Letters Of Intent (LOI) for TEF. More than 30 research programs were proposed. According to these proposals, the re-arrangement of facility layout and the new experimental equipment design are now underway. One of the important developments is to prepare for the application of minor actinide fuels to critical assembly. The development of the technology to handle the high-background minor actinide fuel is being performed. Another important issue is the pulse operation of critical assembly under subcritical condition. The laser charge exchange technique and measurement system for pulse operation are also under development. The latest facility concept reflecting these efforts and user requests based on LOI will be introduced.
