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Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 32 Pages, 2022/02

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

Present status and future perspective of R&D for 3D-ADRES (3-Dimensional Air Dose Rate Evaluation System); Evaluation scheme for air dose rate distributions in city and forest areas towards Fukushima's revitalization

Kim, M.; Malins, A.; Machida, Masahiko; Yoshimura, Kazuya; Saito, Kimiaki; Yoshida, Hiroko*; Yanagi, Hideaki*; Yoshida, Toru*; Hasegawa, Yukihiro*

RIST News, (67), p.3 - 15, 2021/09

no abstracts in English

Journal Articles

Quasifree neutron knockout reaction reveals a small $$s$$-Orbital component in the Borromean nucleus $$^{17}$$B

Yang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.

Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02

 Times Cited Count:10 Percentile:98.7(Physics, Multidisciplinary)

A quasifree ($$p$$,$$pn$$) experiment was performed to study the structure of the Borromean nucleus $$^{17}$$B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for $$1s_{1/2}$$ and $$0d_{5/2}$$ orbitals, and a surprisingly small percentage of 9(2)% was determined for $$1s_{1/2}$$. Our finding of such a small $$1s_{1/2}$$ component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in $$^{17}$$B. The present work gives the smallest $$s$$- or $$p$$-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of $$s$$ or $$p$$ orbitals is not a prerequisite for the occurrence of a neutron halo.

Journal Articles

Study of quasielastic barrier distributions as a step towards the synthesis of superheavy elements with hot fusion reactions

Tanaka, Taiki*; Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Boll, R. A.*; Brewer, N. T.*; Van Cleve, S.*; Dean, D. J.*; Ishizawa, Satoshi*; et al.

Physical Review Letters, 124(5), p.052502_1 - 052502_6, 2020/02

 Times Cited Count:4 Percentile:72.03(Physics, Multidisciplinary)

Journal Articles

Summary of temporal changes in air dose rates and radionuclide deposition densities in the 80 km zone over five years after the Fukushima Nuclear Power Plant accident

Saito, Kimiaki; Mikami, Satoshi; Ando, Masaki; Matsuda, Norihiro; Kinase, Sakae; Tsuda, Shuichi; Yoshida, Tadayoshi; Sato, Tetsuro*; Seki, Akiyuki; Yamamoto, Hideaki*; et al.

Journal of Environmental Radioactivity, 210, p.105878_1 - 105878_12, 2019/12

 Times Cited Count:20 Percentile:87.21(Environmental Sciences)

Journal Articles

Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.

Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07

 Times Cited Count:5 Percentile:62.37(Physics, Multidisciplinary)

Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for $$^{107}$$Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.

Journal Articles

Proton chelating ligands drive improved chemical separations for rhodium

Narita, Hirokazu*; Nicolson, R. M.*; Motokawa, Ryuhei; Ito, Fumiyuki*; Morisaku, Kazuko*; Goto, Midori*; Tanaka, Mikiya*; Heller, W. T.*; Shiwaku, Hideaki; Yaita, Tsuyoshi; et al.

Inorganic Chemistry, 58(13), p.8720 - 8734, 2019/07

 Times Cited Count:6 Percentile:55.42(Chemistry, Inorganic & Nuclear)

JAEA Reports

Technical design of the pressure-resistant chamber for open inspections of the storage containers of nuclear fuel materials

Marufuji, Takato; Sato, Takumi; Ito, Hideaki; Suzuki, Hisashi; Fujishima, Tadatsune; Nakano, Tomoyuki

JAEA-Technology 2019-006, 22 Pages, 2019/05

JAEA-Technology-2019-006.pdf:2.84MB

Radioactive contamination incident occurred at Plutonium Fuel Research Facility (PFRF) in Oarai Research and Development Institute, Japan Atomic Energy Agency on June 6, 2017. During inspection work of storage container containing nuclear fuel materials, the PVC bag packaging in the storage container ruptured when a worker opened the lid in the hood, and a part of contents was spattered over the room. The cause of the increase of internal pressure of the storage container was gas generation by alpha radiolysis of the epoxy resin mixed with nuclear fuel materials. Opening inspection of about 70 similar containers stored in PFRF has been planned to confirm the condition of the contents and to stabilize the stored materials containing organic compounds. For safe and reliable open inspection of the storage containers with high internal pressure in the glove box, it is necessary to develop a pressure-resistant chamber in which the storage containers are opened and the contents are inspected under gastight condition. This report summarizes the concerns and countermeasures of the chamber design and the design results of the chamber.

Journal Articles

Measurement of ambient dose equivalent rates by walk survey around Fukushima Dai-ichi Nuclear Power Plant using KURAMA-II until 2016

Ando, Masaki; Yamamoto, Hideaki*; Kanno, Takashi*; Saito, Kimiaki

Journal of Environmental Radioactivity, 190-191, p.111 - 121, 2018/10

 Times Cited Count:11 Percentile:59.27(Environmental Sciences)

Ambient dose equivalent rates in various environments related to human lives were measured by walk surveys using the KURAMA-II systems from 2013 to 2016 around the Fukushima Dai-ichi Nuclear Power Plant. The dose rate of the locations where the walk survey was performed decreased to about 38% of its initial value in the 42 months, which was beyond that attributable to the physical decay. The air dose rates decreased depending on the level of the evacuation areas, and the decrease was slightly larger in populated areas where humans are active. The comparison of walk survey data with car-borne survey data indicated that the air dose rate varies largely even within a 100 m square area. The dose rates measured by the walk surveys were estimated to be medial of those along roads and those of undisturbed flat ground. The air dose rates measured by the walk surveys decreased quickly compared with the air dose rate from the flat ground measurement.

JAEA Reports

Measurement and analysis of in-vessel component activation and gamma dose rate distribution in Joyo, 2

Yamamoto, Takahiro; Ito, Chikara; Maeda, Shigetaka; Ito, Hideaki; Sekine, Takashi

JAEA-Technology 2017-036, 41 Pages, 2018/02

JAEA-Technology-2017-036.pdf:7.86MB

In the experimental fast reactor Joyo, the damaged upper core structure (UCS) was retrieved into the cask in May 2014 The dose rate on UCS surface was quite high due to the activation for over 30 years operation. In order to attain the optimum safety design, manufacture and operation of equipment for UCS replacement, the method to evaluate UCS surface dose rate was developed on the basis of C/E obtained by the in-vessel dose rate measurement in Joyo. In order to verify the evaluation method, the axial gamma-ray distribution measurement on the surface of the cask, which contained UCS, was conducted using a plastic scintillating optical fiber (PSF) detector. This paper describes the comparison results between calculation and measurement as follows. (1) The measured axial gamma-ray distribution on the cask surface had a peak on proper location with considering the cask shielding structure and agree well with the calculated distribution. (2) The C/E of axial gamma-ray distribution on the cask surface was ranged from 1.1 to 1.7. It was confirmed that the calculation for UCS replacement equipment design had a margin conservatively. Then, the results showed that the developed evaluation method for UCS replacement equipment design was sufficiently reliable.

JAEA Reports

Inspection and repair techniques in reactor vessel of the experimental fast reactor JOYO; Development of devices for retrieving bent MARICO-2 subassembly and completion of retrieval work

Ashida, Takashi; Nakamura, Toshiyuki*; Ito, Hideaki

JAEA-Technology 2017-024, 198 Pages, 2017/11

JAEA-Technology-2017-024.pdf:55.8MB
JAEA-Technology-2017-024-appendix(CD-ROM)-1.zip:298.09MB
JAEA-Technology-2017-024-appendix(CD-ROM)-2.zip:210.77MB

In the experimental fast reactor Joyo, the disconnecting of an irradiation test subassembly MARICO-2 (Material Testing Irradiation Rig with Temperature Control) from its holding mechanism was conducted in May 2007. After the operation, the rotating plug was rotated despite the fact that the test subassembly was not disconnected completely. Consequently, top of wrapper tube of the MARICO-2 subassembly was bent onto the in-vessel storage rack. Since the overhanging part of the subassembly was in the height in which contacts with the upper core structure, it had damaged the bottom surface of the upper core structure. As the result, it was necessary to replace the damaged upper core structure and to retrieve the bent MARICO-2 subassembly for Joyo restart. Retrieval devices for MARICO-2 subassembly consist of a gripper mechanism to lift subassembly together with transfer pot, a guide tube built-in a pantograph mechanism to adjust lifting axis and safety mechanisms to prevent or mitigate falling of MARICO-2 subassembly, a retrieval cask and so on. Design of the retrieval devices have been verified in ex-vessel partial or full-scale mock-up tests and in-vessel function tests. In 2014, MARICO-2 subassembly was successfully retrieved from the reactor vessel by applying these retrieval devices. Then, retrieved subassembly was transported to a hot-cell facility for post-irradiation examinations. Devices have demonstrated expected performance under the actual environmental conditions of a sodium cooled fast reactor. This is a synthetic report about the retrieval work of the deformed and irradiated test subassembly in Joyo. This report includes the detail design and fabrication of the special retrieval device, results of tests for confirmation including the mock-up tests in manufacturer's factory, and results of MARICO-2 retrieval work from the reactor vessel.

Journal Articles

Low-lying dipole strength in $$^{52}$$Cr

Shizuma, Toshiyuki*; Hayakawa, Takehito*; Daito, Izuru*; Ogaki, Hideaki*; Miyamoto, Shuji*; Minato, Futoshi

Physical Review C, 96(4), p.044316_1 - 044316_10, 2017/10

 Times Cited Count:7 Percentile:61.99(Physics, Nuclear)

The low-lying dipole strength in $$^{52}$$Cr was measured in nuclear resonance fluorescence experiments using a quasi-monochromatic, linearly polarized photon beam. The parities of the excited dipole states were determined by the intensity asymmetry of resonantly scattered $$gamma$$-rays with respect to the polarization plane of the incident photon beam. The summed magnetic dipole (M1) strength was determined as $$sum B(M1)uparrow=5.64(34) mu_N^2$$ at excitation energies between 7.5 and 12.1 MeV; the summed electric dipole (E1) strength was obtained as $$sum B(E1)uparrow=73.7(23) times 10^{-3} e^2$$ fm$$^2$$. The observed M1 and E1 strengths were compared via random phase approximation calculations using the Skyrme interaction. The effects of 2 particle-2 hole configuration mixing and tensor force on dipole strength distributions were investigated.

Journal Articles

Shell evolution beyond $$Z$$=28 and $$N$$=50; Spectroscopy of $$^{81,82,83,84}$$Zn

Shand, C. M.*; Podoly$'a$k, Zs.*; G$'o$rska, M.*; Doornenbal, P.*; Obertelli, A.*; Nowacki, F.*; Otsuka, T.*; Sieja, K.*; Tostevin, J. A.*; Tsunoda, T.*; et al.

Physics Letters B, 773, p.492 - 497, 2017/10

 Times Cited Count:18 Percentile:88.47(Astronomy & Astrophysics)

Journal Articles

Reduction and resource recycling of high-level radioactive wastes through nuclear transmutation; Isolation techniques of Pd, Zr, Se and Cs in simulated high level radioactive waste using solvent extraction

Sasaki, Yuji; Morita, Keisuke; Ito, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Takahashi, Yuya*; Kaneko, Masaaki*; Omori, Takashi*; Asano, Kazuhito*

Proceedings of International Nuclear Fuel Cycle Conference (GLOBAL 2017) (USB Flash Drive), 4 Pages, 2017/09

no abstracts in English

Journal Articles

Extraction and separation of Se, Zr, Pd, and Cs including long-lived radionuclides

Sasaki, Yuji; Morita, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Ito, Keisuke; Takahashi, Yuya*; Kaneko, Masaaki*

Solvent Extraction Research and Development, Japan, 24(2), p.113 - 122, 2017/06

The solvent extraction of Se, Zr, Pd, and Cs from nitric acid into 1-octanol (OC) and dodecane has been performed. These elements include long-lived radionuclides in spent nuclear fuels, so a simple separation method is indispensable for the development of the treatment of high-level liquid radioactive waste. It was found that Se can be extracted using phenylenediamine, Zr can be extracted using tetraoctyl diglycolamide and di-2-ethylhexyl phosphoric acid, and Pd can be extracted using (methylimino)bis(dioctylacetamide) and hexaoctylnitrilotriacetamide. These elements can be recovered in over 90% yield by these extractants from nitric acid into OC. A distribution ratio of Cs of greater than 1 can be obtained using di-t-butyldibenzo-18-crown-6. It is clear that 90% recovery of Cs can be achieved using an extraction solvent with ten times the volume of the aqueous phase.

Journal Articles

Development of inspection and repair techniques in reactor vessel of experimental fast reactor "Joyo"; Retrieval of the bent test subassembly

Ashida, Takashi; Ito, Hideaki; Miyamoto, Kazuyuki*; Nakamura, Toshiyuki; Koga, Kazuhiro*; Ohara, Norikazu*; Ino, Hiroichi*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(4), p.210 - 222, 2016/12

In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of material testing rig named "MARICO-2" had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). As the result, for Joyo restart, it was necessary to replace the damaged UCS and to retrieve the bent sub-assembly. This paper describes in-vessel repair techniques performed in the retrieval work of the obstacle inside of the reactor vessel. The devices which were prepared for this work demonstrated expected performance under the environmental conditions of an SFR such as high temperature and radiation dose, and the work was completed in 2014. The successful operation of this retrieval work of the damaged component inside of a reactor vessel will contribute to the development of in-service inspections and repair technics in an SFR.

JAEA Reports

Synthesized research report in the second mid-term research phase, Mizunami Underground Research Laboratory Project, Horonobe Underground Research Laboratory Project and Geo-stability Project (Translated document)

Hama, Katsuhiro; Sasao, Eiji; Iwatsuki, Teruki; Onoe, Hironori; Sato, Toshinori; Fujita, Tomo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Takeda, Masaki; Aoyagi, Kazuhei; et al.

JAEA-Review 2016-014, 274 Pages, 2016/08

JAEA-Review-2016-014.pdf:44.45MB

We synthesized the research results from the Mizunami/Horonobe Underground Research Laboratories (URLs) and geo-stability projects in the second midterm research phase. This report can be used as a technical basis for the Nuclear Waste Management Organization of Japan/Regulator at each decision point from siting to beginning of disposal (Principal Investigation to Detailed Investigation Phase).

Journal Articles

Progress report of Japanese simulation research projects using the high-performance computer system Helios in the International Fusion Energy Research Centre

Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03

The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.

Journal Articles

Uncertainty in predictions of the ambient dose equivalent rates for 30 years following the Fukushima Daiichi Nuclear Power Plant accident

Kinase, Sakae; Takahashi, Tomoyuki*; Sato, Satoshi; Yamamoto, Hideaki; Saito, Kimiaki

Proceedings of 17th NSFS Conference (Internet), p.27 - 33, 2016/02

Journal Articles

Changes in ambient dose equivalent rates around roads at Kawamata town after the Fukushima accident

Kinase, Sakae; Sato, Satoshi; Sakamoto, Ryuichi*; Yamamoto, Hideaki; Saito, Kimiaki

Radiation Protection Dosimetry, 167(1-3), p.340 - 343, 2015/11

 Times Cited Count:6 Percentile:54.79(Environmental Sciences)

174 (Records 1-20 displayed on this page)