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Journal Articles

Role of breakup processes in deuteron-induced spallation reactions at 100-200 MeV/nucleon

Nakayama, Shinsuke; Furutachi, Naoya; Iwamoto, Osamu; Watanabe, Yukinobu*

Physical Review C, 98(4), p.044606_1 - 044606_8, 2018/10

 Times Cited Count:1 Percentile:49.68(Physics, Nuclear)

Use of deuteron-induced spallation reactions at intermediate energies has recently been proposed for transmutation of several long-lived fission products (LLFPs). In the design study of a transmutation system using a deuteron primary beam, accurate cross section data of deuteron-induced reactions on the LLFPs are indispensable. In the present study, production cross sections of residual nuclei in the deuteron-induced reactions on $$^{93}$$Zr and $$^{107}$$Pd at $$100-200$$ MeV/nucleon are analyzed using DEURACS, in which the breakup processes are explicitly taken into account. The calculated values reproduced the experimental data quantitatively well. From a component-by-component analysis, it was found that the components of nucleon absorption make the significant contributions to residual nuclei production. This result strongly indicates that consideration of the breakup processes is essentially important to predict production of residual nuclei in deuteron-induced reactions.

Journal Articles

Method to reduce long-lived fission products by nuclear transmutations with fast spectrum reactors

Chiba, Satoshi*; Wakabayashi, Toshio*; Tachi, Yoshiaki; Takaki, Naoyuki*; Terashima, Atsunori*; Okumura, Shin*; Yoshida, Tadashi*

Scientific Reports (Internet), 7(1), p.13961_1 - 13961_10, 2017/10

 Times Cited Count:2 Percentile:42.02(Multidisciplinary Sciences)

Transmutation of long-lived fission products (LLFPs: $$^{79}$$Se, $$^{93}$$Zr, $$^{99}$$Tc, $$^{107}$$Pd, $$^{129}$$I, and $$^{135}$$Cs) into short-lived or non-radioactive nuclides by fast neutron spectrum reactors without isotope separation has been proposed as a solution to the problem of radioactive wastes disposal. Despite investigation of many methods, such transmutation remains technologically difficult. To establish an effective and efficient transmutation system, we propose a novel neutron moderator material, yttrium deuteride (YD$$_{2}$$), to soften the neutron spectrum leaking from the reactor core. Neutron energy spectra and effective half-lives of LLFPs, transmutation rates, and support ratios were evaluated with the continuous-energy Monte Carlo code MVP-II/MVP-BURN and the JENDL-4.0 cross section library. With the YD$$_{2}$$ moderator in the radial blanket and shield regions, effective half-lives drastically decreased from 10$$^{6}$$ to 10$$^{2}$$ years and the support ratios reached 1.0 for all six LLFPs. This successful development and implementation of a transmutation system for LLFPs without isotope separation contribute to developing a self-consuming cycle of LLFPs using fast spectrum reactors to reduce radioactive waste.

Journal Articles

Present state of partitioning and transmutation of long-lived nuclides, 1; Significance of partitioning and transmutation and partitioning and transmutation systems

Minato, Kazuo; Tsujimoto, Kazufumi; Tanabe, Hiromi*; Fujimura, Koji*

Nippon Genshiryoku Gakkai-Shi, 59(8), p.475 - 479, 2017/08

no abstracts in English

Journal Articles

Studies of the setting of engineered barrier configuration utilized in geologic disposal, 1; Dissolution life-time of vitrified waste glass

Oe, Toshiaki*; Wakasugi, Keiichiro

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 24(1), p.27 - 32, 2017/06

The report estimates the life-time of the waste glass dissolution in the geologic disposal environment. The overall safety report on the geologic disposal in Japan showed very short life-time of approximately 70,000 years under pessimistic assumptions ignoring the temperature decrease due to radioactive decay and dissolution rate reduction due to surface shrinkage. These factors are physically established phenomena and may not be excluded. The dissolution models including these factors of temperature and surface area decreases are discussed and used for re-evaluation. Three fracture models are presented for evaluating the surface area decreases; a single plate, monotonic spheres, spheres having power-law distribution. All models have the same initial volume as the waste glass block for mass conservation and the total surface areas are 10 times higher than the initial pristine block because of the fracture development during production. The results indicate the retention time of 50% of initial mass exceed 100,000 years even by different fracture models and the dissolution life-times are expected for 260,000$$sim$$700,000 years depending on models. These results imply more strong isolation capability of the waste glass than that estimated in the overall safety report.

Journal Articles

Positron annihilation in the near surface of room temperature ionic liquids

Hirade, Tetsuya; O'Rourke, B. E.*; Kobayashi, Yoshinori*

Journal of Physics; Conference Series, 791(1), p.012029_1 - 012029_4, 2017/02

We tried to observe the positron annihilation rates near surface of (room temperature ionic liquids) IL's, such as N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide (TMPA-TFSI) by use of the perpendicular slow positron beamline installed at AIST. The vaper pressure of TMPA-TFSI is very small and hence it is possible to measure the positron annihilation rate in vacuum chamber directly. This represents the first energy variable experimental results of the positron annihilation rate at the near surface of an IL. The triplet positronium annihilation rate seems to be larger at nearer region to the surface of the IL's.

Journal Articles

Current activities and future plans for nuclear data measurements at J-PARC

Kimura, Atsushi; Harada, Hideo; Nakamura, Shoji; Iwamoto, Osamu; Toh, Yosuke; Koizumi, Mitsuo; Kitatani, Fumito; Furutaka, Kazuyoshi; Igashira, Masayuki*; Katabuchi, Tatsuya*; et al.

European Physical Journal A, 51(12), p.180_1 - 180_8, 2015/12

 Percentile:100(Physics, Nuclear)

Journal Articles

Enhanced lattice defect formation associated with hydrogen and hydrogen embrittlement under elastic stress of a tempered martensitic steel

Doshida, Tomoki*; Suzuki, Hiroshi*; Takai, Kenichi*; Hirade, Tetsuya; Oshima, Nagayasu*

NanotechJapan Bulletin (Internet), 8(3), 5 Pages, 2015/07

Studying the creation and time evolution of defects is an important issue for interpreting the hydrogen embrittlement mechanism of steels. We have been studied the relationship between hydrogen embrittlement of high strength steel and lattice defects associated with hydrogen by thermal desorption analysis (TDA) and positron probe microanalyzer (PPMA).

Journal Articles

Development of an H$$^{-}$$-ion source for the High-Intensity Proton Accelerator (J-PARC)

Oguri, Hidetomo; Ueno, Akira; Namekawa, Yuya*; Ikegami, Kiyoshi*

Review of Scientific Instruments, 77(3, Part2), p.03A517_1 - 03A517_3, 2006/03

 Times Cited Count:5 Percentile:65(Instruments & Instrumentation)

The J-PARC Project was started in 2001 as a joint project carried out by JAERI and KEK. At the first stage of the J-PARC, the linac will accelerate the H- ion beam current of 30 mA with a duty factor of 1.25 %. The J-PARC H- ion source driven with a LaB6 filament has regularly delivered more than 35 mA beam with a duty factor of 0.9 % without resorting to cesium. Although the operated duty factor is about 1/3 of the requirement, the filament is not replaced for a half year. At the J-PARC, the lifetime of the tungsten (W) filament was measured by using another H- ion source, which can produce a 72 mA with cesium seeded. The experimental results showed that there is a possibility of the W filament satisfying the lifetime of more than 500 hours, which is J-PARC requirement. We consider the W driven plasma ion source is one of the candidates for the J-PARC source. At present, we are performing the beam test of the cesium free ion source driven with W. We will present the experimental data of the beam test in this conference.

Journal Articles

Status report of the JAERI tandem accelerator

Matsuda, Makoto; Takeuchi, Suehiro; Tsukihashi, Yoshihiro; Horie, Katsuzo*; Ouchi, Isao*; Hanashima, Susumu; Abe, Shinichi; Ishizaki, Nobuhiro; Tayama, Hidekazu; Nakanoya, Takamitsu; et al.

Dai-18-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.11 - 14, 2005/11

no abstracts in English

JAEA Reports

Status and future plan of research and development on partitioning and transmutation technology for long-lived nuclides in JAERI

Oigawa, Hiroyuki; Nishihara, Kenji; Minato, Kazuo; Kimura, Takaumi; Arai, Yasuo; Morita, Yasuji; Nakayama, Shinichi; Katakura, Junichi

JAERI-Review 2005-043, 193 Pages, 2005/09


JAERI has been conducting research and development on partitioning and transmutation (P&T) technology for long-lived nuclides to develop the double-strata fuel cycle concept, in accordance with the Atomic Energy Commission's "Research and Development of Technologies for Partitioning and Transmutation of Long-lived Nuclides - Status and Evaluation Report" issued in 2000. The double-strata fuel cycle concept consists of four major processes: partitioning, fuel fabrication, transmutation, and fuel processing. The five-year achievement and future perspectives for the technology on these processes are presented in this report. It also provides an analytical study on impacts of introducing P&T technology on waste management, and on deployment of P&T for the future nuclear energy system.

Journal Articles

Impact erosion by pressure wave propagation in mercury target for pulsed spallation neutron source

Futakawa, Masatoshi

Nippon Genshiryoku Gakkai-Shi, 47(8), p.530 - 535, 2005/08

no abstracts in English

Journal Articles

Positron lifetime measurement on centrifuged Bi$$_{3}$$Pb$$_{7}$$ intermetallic compound

Ono, Masao; Huang, X. S.*; Shibata, Yasuhiro*; Iguchi, Yusuke*; Sakai, Seiji; Maekawa, Masaki; Chen, Z. Q.*; Osakabe, Toyotaka; Kawasuso, Atsuo; Naramoto, Hiroshi*; et al.

Proceedings of 1st International Conference on Diffusion in Solids and Liquids (DSL 2005), p.531 - 533, 2005/07

Recently, we formed atomic-scale graded structures in some miscible alloys and observed the decomposition in Bi$$_{3}$$Pb$$_{7}$$ intermetallic compound by sedimentation of atoms under strong gravitational field. In this study, we measured positron lifetime of centrifuged Bi$$_{3}$$Pb$$_{7}$$, to which the composition change was very small as it was treated at low temperature. It was found that the positron lifetime became longer than that of starting state. This indicated that the point defects (vacancy or divacancy) increased in the sample by centrifugal treatment. We are now investigating the relationship between increase in point defects and sedimentation of atoms.

Journal Articles

Status of the ECR ion source for TRIAC

Nakanoya, Takamitsu; Matsuda, Makoto; Fujii, Yoshio*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.729 - 730, 2005/07

TRIAC (Tokai Radioactive Ion Accelerator Complex) facility can accelerate both radioactive and stable ion beams up to 1.1Mev/u. In this facility, an ECR ion source is used for production of stable ion beams. Stable ion beams are used mainly as a pilot beam for radioactive ion beam. ECR ion source is required to produce many kinds of ion species, not only gas state elements. So, we developed a high temperature oven for obtaining metal ion beams. This paper describes the design and detail of the oven and experimental results.

Journal Articles

DPA Calculation in Japanese Spallation Neutron Source

Harada, Masahide; Watanabe, Noboru; Konno, Chikara; Meigo, Shinichiro; Ikeda, Yujiro; Niita, Koji*

Journal of Nuclear Materials, 343(1-3), p.197 - 204, 2005/06

 Times Cited Count:21 Percentile:14.34(Materials Science, Multidisciplinary)

For a construction of maintenance and storage scenarios for JSNS, lives of structure material need to be estimated. DPA (Displacement per Atom) was a major index of radiation damage. So we evaluated DPA value of each component. Function of the DPA calculation was equipped to the PHITS code, which was particle and heavy ion transport code. For DPA calculation, displacement cross section was necessary. Displacement cross sections of neutron below 150 MeV were processed by the NJOY code from LA150 library and those of neutron above 150MeV and proton in the all energy region were obtained from energies of fragments calculated in the PHITS. By using the PHITS, we calculated DPA values and DPA mapping. We obtained that the peak DPA values at end of 5000MWh operation were 4.1 for target vessel, 2.8 for reflector and moderator vessels, and 0.4 for proton beam windows, respectively. We estimated the target life at 1 year and the moderator life at 6 year.

Journal Articles

Structural defects in SiO$$_2$$/SiC interface probed by a slow positron beam

Maekawa, Masaki; Kawasuso, Atsuo; Chen, Z. Q.; Yoshikawa, Masahito; Suzuki, Ryoichi*; Odaira, Toshiyuki*

Applied Surface Science, 244(1-4), p.322 - 325, 2005/05

 Times Cited Count:10 Percentile:53.05(Chemistry, Physical)

no abstracts in English

Journal Articles

Role of trapped and solvated electrons in Ps formation

Stepanov, S. V.*; Byakov, V. M.*; He, C.*; Hirade, Tetsuya; Mikhin, K. V.*

Acta Physica Polonica A, 107(4), p.642 - 650, 2005/00

Role of trapped and solvated electrons in Ps formation is discussed. Combination of thermalized positron with such electrons is energetically possible and may contribute to Ps formation. Contrary to the positron reaction with a quasi-free electron, this process is not limited to picosecond times, but proceeds on a timescale of nanoseconds. In this case conventional exponential deconvolution of row lifetime positron annihilation spectra becomes questionable. Rigorous treatment of the data needs nonexponential deconvolution, based on an adequate physical input. Such an approach is suggested here. Its reduced form is used for interpretation of the Ps formation data in polyethylene, EMMA and PMMA in dark and in light vs. time of the measurement and temperature. Parameters characterized accumulation of trapped electrons and their recombination with counter ions and positrons are obtained.

Journal Articles

Luminescence properties of tetravalent uranium in aqueous solution

Kirishima, Akira; Kimura, Takaumi; Nagaishi, Ryuji; Tochiyama, Osamu*

Radiochimica Acta, 92(9-11), p.705 - 710, 2004/12

 Times Cited Count:23 Percentile:15.16(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Organic scintillators containing $$^{10}$$B for neutron detectors

Kamaya, Eiki*; Matsumoto, Fukashi*; Kondo, Yasuhiro*; Chujo, Yoshiki*; Katagiri, Masaki

Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.329 - 331, 2004/08

 Times Cited Count:12 Percentile:32.62(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

Filament lifetime test of the negative ion source for the high intensity proton accelerator

Oguri, Hidetomo; Namekawa, Yuya*

JAERI-Tech 2004-053, 35 Pages, 2004/07


The high intensity proton accelerator facility project (J-PARC) aims to pursue frontier science in materials science, nuclear physics and nuclear technology, using an accelerator complex at the highest beam power in the world. An H$$^{-}$$ ion source for the project is required to produce a beam current of $$>$$60 mA and an emittance of $$<$$0.20 $$pi$$mm.mrad with a duty factor of 2.5 %. In addition, the ion source must be run for 500 h continuously without maintenance. As a result of the beam test, the beam current and the emittance of 72 mA and 0.15 $$pi$$mm.mrad were achieved in the Cs seeded operation, respectively. Because a lifetime of the filament cathode is one of the main restrictions for the maintenance cycle, we started to perform a filament lifetime test. As the result of the test, we succeeded for 258 h arc operation at the arc power of 30 kW with the duty factor of 3 %. Moreover, the results showed that there is a possibility of achievement $$>$$800 h lifetime by change the connection between filament and arc power supply and the optimization of the filament shape.

Journal Articles

Reseach and development of superconducting twin quarter wave resonator for the acceleration of low velocity heavy ions

Kabumoto, Hiroshi; Takeuchi, Suehiro; Matsuda, Makoto; Nakanoya, Takamitsu

Dai-17-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.135 - 137, 2004/06

no abstracts in English

286 (Records 1-20 displayed on this page)