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JAEA Reports

Current status and upgrading strategies of J-PARC Materials and Life Science Experimental Facility (MLF) and related components

Teshigawara, Makoto; Nakamura, Mitsutaka; Kinsho, Michikazu; Soyama, Kazuhiko

JAEA-Technology 2021-022, 208 Pages, 2022/02


The Materials and Life science experimental Facility (MLF) is an accelerator driven pulsed spallation neutron and muon source with a 1 MW proton beam. The construction began in 2004, and we started beam operation in 2008. Although problems such as exudation of cooling water from the target container have occurred, as of April 2021, the proton beam power has reached up to 700 kW gradually, and stable operation is being performed. In recent years, the operation experience of the rated 1 MW has been steadily accumulated. Several issues such as the durability of the target container have been revealed according to the increase in the operation time. Aiming at making a further improvement of MLF, we summarized the current status of achievements for the design values, such as accelerator technology (LINAC and RCS), neutron and muon source technology, beam transportation of these particles, detection technology, and neutron and muon instruments. Based on the analysis of the current status, we tried to extract improvement points for upgrade of MLF. Through these works, we will raise new proposals that promote the upgrade of MLF, attracting young people. We would like to lead to the further success of researchers and engineers who will lead the next generation.

JAEA Reports

Evaluation of the minimum critical amount for heterogeneous lattice systems composed of fuel rods utilized in low-power water-moderated research and test reactors by using continuous-energy Monte Carlo code MVP with JENDL-4.0

Yanagisawa, Hiroshi

JAEA-Technology 2021-023, 190 Pages, 2021/11


Computational analyses on nuclear criticality characteristics were carried out for heterogeneous lattice systems composed of water moderator and fuel rods utilized in low-power research and test reactors, in which the depletion of fuel due to burnup is relatively small, by using the continuous-energy Monte Carlo code MVP Version 2 with the evaluated nuclear data library JENDL-4.0. In the analyses, the minimum critical number of fuel rods was evaluated using calculated neutron multiplication factors for the heterogeneous systems of the uranium dioxide fuel rod in the Static Experiments Critical Facility (STACY) and the Tank-type Critical Assembly (TCA), and the uranium-zirconium hydride fuel rod in the Nuclear Safety Research Reactor (NSRR). In addition, six sorts of the ratio of reaction rates, which are components of neutron multiplication factors, were calculated in the analyses to explain the variation of neutron multiplication factors with the ratio of water moderator to fuel volume in a unit fuel rod cell. Those results of analyses are considered to be useful for the confirmation of reasonableness and validity of criticality safety measures as data showing criticality characteristics for water-moderated heterogeneous lattice systems composed of the existing fuel rods in research and test reactors, of which criticality data are not sufficiently provided by the Criticality Safety Handbook.

Journal Articles

Delayed gamma-ray spectroscopy, 2; Design study of moderator for a practical system

Rossi, F.; Rodriguez, D.; Takahashi, Tone; Seya, Michio; Koizumi, Mitsuo

Nihon Kaku Busshitsu Kanri Gakkai Dai-39-Kai Nenji Taikai Rombunshu (CD-ROM), 3 Pages, 2018/11

This paper (presentation) reports on the design study for seeking compactness of moderator (and reflector) structure for the Delayed Gamma-ray Spectroscopy Non Destructive Assay system to be applied for verification of fissile isotopic (Pu-239, Pu-241 and U-235) composition ratio in High Radioactive Nuclear Material sample such as dissolved solution of reprocessing facility. We first investigated advantages and disadvantages of using different compact neutron sources as DT and DD neutron generators. This led us to the conclusion of using DD sources to achieve a compact (and practical) NDA system. Based on MCNP simulations, with the use of a DD neutron generator, a preliminary optimization study was performed and will be shown here.

Journal Articles

Fundamental aspects of neutron moderators and neutron beam optics for designing high intensity laser-driven neutron source

Ikeda, Yujiro; Shimizu, Hirohiko*

Reza Kenkyu, 46(11), p.641 - 646, 2018/11

In viewing significant progresses in technical achievement toward a high-intensity neutron source driven by a high-power laser came up with the high power laser development, we have reviewed the currently most advanced moderator system and neutron optics, which are the key elements for the neutron beam applications. Regarding the moderators, concepts adopted in J-PARC pulsed neutron source, which is one of most advanced system, were described to give a baseline design. Also a new direction of moderator concept is shown, which could be a high brightness candidate for the high-intensity laser driven system. On the neutron optics, the most fundamental consideration is primarily reviewed along with recent progress in new devises for enrichment of neutron-beam characteristics.

Journal Articles

Experimental validation of the brightness distribution on the surfaces of coupled and decoupled moderators composed of 99.8% parahydrogen at the J-PARC pulsed spallation neutron source

Harada, Masahide; Teshigawara, Makoto; Oi, Motoki; Klinkby, E.*; Zanini, L.*; Batkov, K.*; Oikawa, Kenichi; Toh, Yosuke; Kimura, Atsushi; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 903, p.38 - 45, 2018/09

 Times Cited Count:5 Percentile:64.98(Instruments & Instrumentation)

Journal Articles

Present fabrication status of spare moderators and reflector in J-PARC spallation neutron source

Teshigawara, Makoto; Harada, Masahide; Oi, Motoki; Takada, Hiroshi

Journal of Physics; Conference Series, 1021(1), p.012061_1 - 012061_4, 2018/06

 Times Cited Count:0 Percentile:0.11

At the spallation neutron source of J-PARC, the structural material of moderators and reflector, such as an aluminum alloy, is going to reach to the design value (20 DPA) around 2020 by an accumulation of irradiation-damage. We started the fabrication of the spare moderators and reflector in 2013 with following design of two improvements. The invar joints, such as invar-A6061 and invar- SS316L joints were newly developed to utilize them in the cryogenic multi-layered pipe with 5th annular geometry, improving the fabrication procedure much simple. The Gold-Indium-Cadmium (Au-In-Cd) as a decoupler material is also developed to reduce residual radioactivity of the used components significantly for the decoupled moderator. In this presentation, we will report these results and progress of fabrication.

Journal Articles

Measurements of neutronic characteristics of rectangular and cylindrical coupled hydrogen moderators

Kai, Tetsuya; Kamiyama, Takashi*; Hiraga, Fujio*; Oi, Motoki; Hirota, Katsuya*; Kiyanagi, Yoshiaki*

Journal of Nuclear Science and Technology, 55(3), p.283 - 289, 2018/03

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Current status of the high intensity pulsed spallation neutron source at J-PARC

Takada, Hiroshi

Plasma and Fusion Research (Internet), 13(Sp.1), p.2505013_1 - 2505013_8, 2018/03

The pulsed spallation neutron source of Japan Proton Accelerator Research Complex (J-PARC) has been supplying users with high intensity and sharp pulse cold neutrons using the moderators with following distinctive features; (1) 100% para-hydrogen for increasing pulse peak intensity with decreasing pulse tail, (2) cylindrical shape with 14 cm diam.$$times$$12 cm long for providing high intensity neutrons to wide neutron extraction angles of 50.8$$^{circ}$$, (3) neutron absorber made from Ag-In-Cd alloy to make pulse width narrower and pulse tails lower. Actually, it was measured at a low power operation that high neutron intensity of 4.5$$times$$10$$^{12}$$ n/cm$$^{2}$$/s/sr could be emitted from the coupled moderator surface for 1-MW operation, and a superior resolution of $$Delta$$d/d = 0.035% was achieved at a beamline (BL8) with a poisoned moderator, where d is the d-spacing of reflection. Towards the goal to achieve the target operation at 1-MW for 5000 h in a year, technical developments to mitigate cavitation damages on the target vessel with injecting gas micro-bubbles into mercury target and design improvement of target vessel structure to reducing welds and bolt connections as much as possible are under way.

Journal Articles

Implementation of a low-activation Au-In-Cd decoupler into the J-PARC 1 MW short pulsed spallation neutron source

Teshigawara, Makoto; Ikeda, Yujiro; Oi, Motoki; Harada, Masahide; Takada, Hiroshi; Kakishiro, Masanori*; Noguchi, Gaku*; Shimada, Tsubasa*; Seita, Kyoichi*; Murashima, Daisuke*; et al.

Nuclear Materials and Energy (Internet), 14, p.14 - 21, 2018/01

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

We developed an Au-In-Cd (AuIC) decoupler material to reduce induced radioactivity instead of Ag-In-Cd one, which has a cut off energy of 1eV. In order to implement it into an actual moderator-reflector assembly, a number of critical engineering issues need to be resolved with regard to large-sized bonding between AuIC and A5083 alloys by the hot isostatic pressing process. We investigated this process in terms of the surface conditions, sizes, and heat capacities of large AuIC alloys. We also show a successful implementation of an AuIC decoupler into a reflector assembly, resulting in a remarkable reduction of radioactivity by AuIC compared to AIC without sacrificing neutronic performance.

Journal Articles

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 1; Pulsed spallation neutron source

Takada, Hiroshi; Haga, Katsuhiro; Teshigawara, Makoto; Aso, Tomokazu; Meigo, Shinichiro; Kogawa, Hiroyuki; Naoe, Takashi; Wakui, Takashi; Oi, Motoki; Harada, Masahide; et al.

Quantum Beam Science (Internet), 1(2), p.8_1 - 8_26, 2017/09

At the Japan Proton Accelerator Research Complex (J-PARC), a pulsed spallation neutron source provides neutrons with high intensity and narrow pulse width to promote researches on a variety of science in the Materials and life science experimental facility. It was designed to be driven by the proton beam with an energy of 3 GeV, a power of 1 MW at a repetition rate of 25 Hz, that is world's highest power level. A mercury target and three types of liquid para-hydrogen moderators are core components of the spallation neutron source. It is still on the way towards the goal to accomplish the operation with a 1 MW proton beam. In this paper, distinctive features of the target-moderator-reflector system of the pulsed spallation neutron source are reviewed.

JAEA Reports

Developments of high-performance moderator vessel for JRR-3 cold neutron source

Arai, Masaji; Tamura, Itaru; Hazawa, Tomoya

JAEA-Technology 2015-010, 52 Pages, 2015/05


In the Department of Research Reactor and Tandem Accelerator, developments of high-performance CNS moderator vessel that can produce cold neutron intensity about two times higher compared to the existing vessel have been performed in the second medium term plans. We compiled this report about the technological development to solve several problems with the design and manufacture of new vessel. In the present study, design strength evaluation, mockup test, simulation for thermo-fluid dynamics of the liquid hydrogen and strength evaluation of the different-material-bonding were studied. By these evaluation results, we verified that the developed new vessel can be applied to CNS moderator vessel of JRR-3.

Journal Articles

Development of aluminum (Al5083)-clad ternary Ag-In-Cd alloy for JSNS decoupled moderator

Teshigawara, Makoto; Harada, Masahide; Saito, Shigeru; Oikawa, Kenichi; Maekawa, Fujio; Futakawa, Masatoshi; Kikuchi, Kenji; Kato, Takashi; Ikeda, Yujiro; Naoe, Takashi*; et al.

Journal of Nuclear Materials, 356(1-3), p.300 - 307, 2006/09

 Times Cited Count:9 Percentile:56.05(Materials Science, Multidisciplinary)

We adopted silver-indium-cadmium (Ag-In-Cd) alloy as a material of decoupler for decoupled moderator in JSNS. However, from the heat removal and corrosion protection points of view, the Ag-In-Cd alloy is needed to clad between Al alloys (Al5083). We attempted to obtain good bonding conditions for between Al5083 and ternary Ag-In-Cd alloys by HIPing tests. The good HIP condition was found for small test piece ($$Phi$$20mm). Though a hardened layer due to the formation of AlAg$$_{2}$$ was found in the bonding layer, the rupture strength of the bonding layer was more than 20 MPa, which was the calculated design stress. Bonding tests of a large size piece (200$$times$$200$$times$$30 mm$$^{3}$$), which simulated the real scale, were also performed according to the results of small size tests. The result also gave good bonding and enough required-mechanical-strength, however the rupture strength of the large size test was smaller than that of small one.

Journal Articles

Deterioration of pulse characteristics and burn-up effects with an engineering model in Japanese spallation neutron source

Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto; Kai, Tetsuya; Maekawa, Fujio; Kato, Takashi; Ikeda, Yujiro

LA-UR-06-3904, Vol.2, p.700 - 709, 2006/06

Pulse characteristics data for every neutron beam line are indispensable in designing devices for neutron scattering experiments of JSNS. A detailed model was built and pulse characteristics of each beam line were estimated using the PHITS code and the MCNP-4C code. These results have been disclosed on the J-PARC homepage since September 2004. Due to changes of moderator shapes in a progress of manufacture design, we observed from the calculation that pulse structures of decoupled moderators were deteriorated, especially, those of pulse tail. We found that this deterioration was caused by leakage neutron from gaps between decouplers and absorbing liners of the reflector. For a final stage of the manufacture design, we carefully tried to find other factors which deteriorated the pulse characteristics. Furthermore, pulse structures of poisoned and unpoisoned decoupled moderators were evaluated with the consideration of heterogeneous burn-up and leakage neutron spectra including high-energy region up to GeV were estimated for each neutron beam hole.

Journal Articles

Neutron facility at high intensity proton accelerator project

Oyama, Yukio; Ikeda, Yujiro

Hoshasen To Sangyo, (107), p.45 - 51, 2005/09

JAERI and KEK are jointly conducting high intensity proton accelerator project (J-PARC). The outline of the J-PARC project and a design concept of the neutron source facility at J-PARC are described in detail.

Journal Articles

Neutronic performance of rectangular and cylindrical coupled hydrogen moderators in wide-angle beam extraction of low-energy neutrons

Kai, Tetsuya; Harada, Masahide; Teshigawara, Makoto; Watanabe, Noboru; Kiyanagi, Yoshiaki*; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 550(1-2), p.329 - 342, 2005/09

 Times Cited Count:16 Percentile:74.09(Instruments & Instrumentation)

Neutronic study was performed on coupled hydrogen moderators to maximize time-integrated and pulse-peak intensities of slow neutrons when a large number of beams was required. The total increased with the number of beams, although the average decreased due to a reflector-missing by the beam extraction holes in the reflector. At a large beam extraction angle (25 degree), the spatial distribution of the vector-flux of neutrons was undesirable for a rectangular shape moderator. As an alternative we proposed a cylindrical shape one, resulting in a much improved spatial distribution. In addition, neutronic performance was calculated as a function of the diameter, indicating the optimal diameter was about 140 mm. The cylindrical one gave higher pulse-peak intensities with narrower pulse widths without penalty in time-integrated intensities and pulse decay characteristics, providing a more uniform angle-dependence. Some explanations are given for the difference in the pulse characteristics between the two. We decided to adopt the cylindrical one for the Japanese spallation neutron source.

Journal Articles

Cladding technique for development of Ag-In-Cd decoupler

Teshigawara, Makoto; Harada, Masahide; Saito, Shigeru; Kikuchi, Kenji; Kogawa, Hiroyuki; Ikeda, Yujiro; Kawai, Masayoshi*; Kurishita, Hiroaki*; Konashi, Kenji*

Journal of Nuclear Materials, 343(1-3), p.154 - 162, 2005/08

 Times Cited Count:10 Percentile:59.05(Materials Science, Multidisciplinary)

For decoupled and poisoned moderator, a thermal neutron absorber, i.e., decoupler, is located around the moderator to give neutron beam with a short decay time. A B4C decoupler is already utilized, however, it is difficult to use in a MW class source because of He void swelling and local heating by (n,a) reaction. Therefore, a Ag-In-Cd (AIC) alloy which gives energy-dependence of macroscopic neutron cross section like that of B$$_{4}$$C was chosen. However, from heat removal and corrosion protection points of view, AIC is needed to bond between an Al alloy (A6061-T6), which is the structural material of a moderator. An AIC plate is divided into a Ag-In (15wt%) and Ag-Cd (35wt%) plate to extend the life time, shorten by burn up of Cd. We performed bonding tests by HIP (Hot Isostatic Pressing). We found out that a better HIP condition was holding at 803 K, 100 MPa for 1 h for small test pieces (f20mm). Though a hardened layer is found in the bonding layer, the rupture strength of the bonding layer is more than 20 MPa, which is less than that of the design stress.

Journal Articles

Current status of 1 MW pulse spallation neutron source (JSNS) of J-PARC

Ikeda, Yujiro

Journal of Nuclear Materials, 343(1-3), p.7 - 13, 2005/08

 Times Cited Count:23 Percentile:83.1(Materials Science, Multidisciplinary)

This paper reports the current status of The Materials and Life Experimental Facility construction under the high intensity proton accelerator projet(J-PARC), which has been conducted by JAERI and KEK collaboratively.Alng with designs and schedule of the neutron source, critical technical issues, e.g., mercury target material and moderator materials, which are still remained to be settled, and activities for development are shown.

Journal Articles

Design of a single moderator-type neutron spectrometer with enhanced energy resolution in energy range from a few to 100 keV

Tanimura, Yoshihiko; Saegusa, Jun; Yoshizawa, Michio; Yoshida, Makoto

Nuclear Instruments and Methods in Physics Research A, 547(2-3), p.592 - 600, 2005/08

 Times Cited Count:7 Percentile:50.55(Instruments & Instrumentation)

The moderator structure of a neutron spectrometer was optimized with a Monte Carlo code of MCNP-4B. The spectrometer consists of a cylindrical moderator and a position-sensitive thermal neutron detector. It can obtain an energy spectrum from thermal neutron distribution along the cylindrical axis of the moderator. The structure of the moderator was improved by putting a low hydrogen density material in the front of a high hydrogen density one and inserting a neutron absorber which eliminated thermal neutrons diffusing in the moderator. These improvements make energy resolution of the spectrometer better especially for the low energy neutrons from a few tens to 100 keV. The designed spectrometer can be applied to the measurement of energy spectrum over a neutron energy range from a few keV to 20 MeV.

JAEA Reports

Remote handling design for moderator-reflector maintenance in JSNS

Teshigawara, Makoto; Aizawa, Hideyuki; Harada, Masahide; Kinoshita, Hidetaka; Meigo, Shinichiro; Maekawa, Fujio; Kaminaga, Masanori; Kato, Takashi; Ikeda, Yujiro

JAERI-Tech 2005-029, 24 Pages, 2005/05


This report introduces the present design status of remote-handling devices for activated and used components such as moderator and reflector in a spallation neutron source of the Material and Life Science Facility (MLF) at J-PARC. The design concept and maintenance scenario are also mentioned. A key maintenance scenario adopts that the used components should be taken out from the MLF to the other storage facility after the volume reduction of them. Almost full remote handling is available to the maintenance work except for the connection/disconnection pipes of the cooling water. Total six remote handling devices are used for moderator-reflector maintenance. They are also available to the proton beam window and muon target maintenance. Maintenance scenario is separated into two works. One is to replace used components to new ones during beam-stop and the other is dispose used components during beam operation. Required period of replacement work is estimated to be $$sim$$15 days, on the other hand, the disposal work is $$sim$$26 days after dry up work ($$sim$$30 days), respectively.

Journal Articles

Neutronic studies on decoupled hydrogen moderator for a short-pulse spallation source

Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto; Kai, Tetsuya; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 539(1-2), p.345 - 362, 2005/02

 Times Cited Count:18 Percentile:77(Instruments & Instrumentation)

Neutronic studies of decoupled hydrogen moderators were performed by calculations taking into account para hydrogen content, decoupling energy, moderator dimensions/shapes and reflector material. Low-energy parts of calculated spectral intensities with different para hydrogen contents were analyzed by a modified Maxwell function to characterize neutron spectra. The result shows that a 100% para hydrogen moderator gives the highest pulse peak intensity together with the narrowest pulse width and the shortest decay times. Pulse broadening with a reflector was explained by time distributions of source neutrons entering into the moderator through a decoupler. Material dependence of time distribution was studied. A decoupling energy higher than 1 eV does not bring about a large improvement in pulse widths and decay times, even at a large penalty in the peak intensity. The optimal moderator thickness was also discussed for a rectangular parallelepiped shape and a canteen shape moderators.

73 (Records 1-20 displayed on this page)