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Ariyoshi, Gen; Saruta, Koichi; Kogawa, Hiroyuki; Futakawa, Masatoshi; Maeno, Koki*; Li, Y.*; Tsutsui, Kihei*
Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.1407 - 1420, 2023/08
Cavitation damage on a target vessel due to proton beam-induced pressure waves is one of the crucial issues for the pulsed neutron source using a mercury spallation target. As a mitigation technique for the damage, the helium microbubble injection into the mercury has been carried out by using a swirl bubbler in order to utilize compressibility of bubbles. Moreover, double-walled structure, which consists of an outer wall and an inner wall, has been applied as the target head structure. In this study, we aim to develop an abnormality diagnostic technology to detect the inner wall cracking, which is caused by such cavitation damage, from the outside of the target vessel. The mercury flow fields in the case with the cracking are evaluated by computational fluid dynamics analysis based on finite element method. And then, effect of the cracking on the flow field is discussed from the point of view of the flow-induced vibration and the acoustic vibration.
Naoe, Takashi; Kinoshita, Hidetaka; Wakui, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro
JAEA-Technology 2022-018, 43 Pages, 2022/08
JAEA-Technology-2022-018.pdf:7.84MB
In the liquid mercury target system for the pulsed spallation neutron source of Materials and Life science experimental Facility (MLF) at the Japan in the Japan Proton Accelerator Research Complex (J-PARC), cavitation that is generated by the high-energy proton beam-induced pressure waves, resulting severe erosion damage on the interior surface of the mercury target vessel. The erosion damage is increased with increasing the proton beam power, and has the possibility to cause the leakage of mercury by the penetrated damage and/or the fatigue failure originated from erosion pits during operation. To achieve the long term stable operation under high-power proton beam, the mitigation technologies for cavitation erosion consisting of surface modification on the vessel interior surface, helium gas microbubble injection, double-walled beam window structure has been applied. The damage on interior surface of the vessel is never observed during the beam operation. Therefore, after the target operation term ends, we have cut out specimen from the target nose of the target vessel to inspect damaged surface in detail for verification of the cavitation damage mitigation technologies and lifetime estimation. We have developed the techniques of specimen cutting out by remote handling under high-radiation environment. Cutting method was gradually updated based on experience in actual cutting for the used target vessel. In this report, techniques of specimen cutting out for the beam entrance portion of the target vessel in high-radiation environment and overview of the results of specimen cutting from actual target vessels are described.
Teshigawara, Makoto; Nakamura, Mitsutaka; Kinsho, Michikazu; Soyama, Kazuhiko
JAEA-Technology 2021-022, 208 Pages, 2022/02
JAEA-Technology-2021-022.pdf:14.28MB
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.
for a mercury target induced by 3-GeV protonsMatsuda, Hiroki; Iwamoto, Hiroki; Meigo, Shinichiro; Takeshita, Hayato*; Maekawa, Fujio
Nuclear Instruments and Methods in Physics Research B, 483, p.33 - 40, 2020/11
Times Cited Count：3 Percentile：36.4(Instruments & Instrumentation)A thick target neutron yield for a mercury target at an angle of 180 from the incident beam direction is measured with the time-of-flight method using a 3-GeV proton beam at the Japan Proton Accelerator Research Complex (J-PARC). Comparing the experimental result with a Monte Carlo particle transport simulation by the Particle and Heavy Ion Transport code System (PHITS) shows that there are apparent discrepancies. We find that this trend is consistent with an experimental result of neutron-induced re- action rates obtained using indium and niobium activation foils. Comparing proton-induced neutron-production double-differential cross-sections for a lead target at backward directions between the PHITS calculation and experimental data suggests that the dis- crepancies for our experiments would be linked to the neutron production calculation around 3 GeV by the PHITS spallation model and/or the calculation of nonelastic cross-sections around 3 GeV in the particle transport simulation.
Takada, Hiroshi; Haga, Katsuhiro
JPS Conference Proceedings (Internet), 28, p.081003_1 - 081003_7, 2020/02
At the Japan Proton Accelerator Research Complex (J-PARC), the pulsed spallation neutron source has been in operation with a redesigned mercury target vessel from October 2017 to July 2018, during which the operational beam power was restored to 500 kW and the operation with a 1-MW equivalent beam was demonstrated for one hour. The target vessel includes a gas-micro-bubbles injector and a 2-mm-wide narrow mercury flow channel at the front end as measures to suppress the cavitation damage. After the operating period, it was observed that the cavitation damage at the 3-mm-thick front end of the target vessel could be suppressed less than 17.5 
m.
Miyahara, Shinya*; Ohdaira, Naoya*; Arita, Yuji*; Maekawa, Fujio; Matsuda, Hiroki; Sasa, Toshinobu; Meigo, Shinichiro
Nuclear Engineering and Design, 352, p.110192_1 - 110192_8, 2019/10
Times Cited Count：5 Percentile：48.99(Nuclear Science & Technology)Lead-Bismuth Eutectic (LBE) is used as a spallation neutron target and coolant materials of Accelerator Driven System (ADS), and many kinds of elements are produced as spallation products. It is important to evaluate the release and transport behavior of the spallation products in the LBE. The inventories and the physicochemical composition of the spallation products produced in LBE have been investigated for an LBE loop in the ADS Target Test Facility (TEF-T) in J-PARC. The inventories of the spallation products in the LBE were estimated using the PHITS code. The physicochemical composition of the spallation products in the LBE was calculated using the Thermo-Calc code under the conditions of the operation temperatures of LBE from 350C to 500C and the oxygen concentrations in LBE from 10 ppb to 1 ppm. The calculation showed that the 5 elements of Rb, Tl, Tc, Os, Ir, Pt, Au and Hg were soluble in LBE under the all given conditions and any kinds of compound were not formed in LBE. It was suggested that the oxides of Ce, Sr, Zr and Y were stable as CeO
, SrO, ZrO and YO
in the LBE.
Kondo, Hiroo*; Kanemura, Takuji*; Park, C. H.*; Oyaizu, Makoto*; Hirakawa, Yasushi; Furukawa, Tomohiro
Fusion Engineering and Design, 146(Part A), p.285 - 288, 2019/09
Times Cited Count：1 Percentile：11.15(Nuclear Science & Technology)Herein, the wall shear stress in a double contraction nozzle has been evaluated experimentally to produce a liquid lithium (Li) target as a beam target for intense fusion neutron sources such as the International Fusion Materials Irradiation Facility (IFMIF), the Advanced Fusion Neutron Source (A-FNS), and the DEMO Oriented Neutron Source (DONES). The boundary layer thickness and wall shear stress are essential physical parameters to understand erosion-corrosion by the high-speed liquid Li flow in the nozzle, which is the key component in producing a stable Li target. Therefore, these parameters were experimentally evaluated using an acrylic mock-up of the target assembly. The velocity distribution in the nozzle was measured by a laser-doppler velocimeter and the momentum thickness along the nozzle wall was calculated using an empirical prediction method. The resulting momentum thickness was used to estimate the variation of the wall shear stress along the nozzle wall. Consequently, the wall shear stress was at the maximum in the second convergent section in front of the nozzle exit.
Tsai, P.-E.; Heilbronn, L. H.*; Lai, B.-L.*; Iwata, Yoshiyuki*; Murakami, Takeshi*; Sheu, R.-J.*
Nuclear Instruments and Methods in Physics Research B, 449, p.62 - 70, 2019/06
Times Cited Count：3 Percentile：32.64(Instruments & Instrumentation)The secondary neutrons produced from 100- and 230-MeV/nucleon He ions, respectively, stopping in the thick iron, PMMA and water targets are measured by the time of flight method combined with the pulse shape discrimination of liquid scintillators. The experimental data show that the secondary neutrons were contributed from breakup of projectiles, emission from overlap regions of projectile nuclei and target nuclei, and evaporation of projectiles and target nuclei. The measured double-differential thick target neutron yields, angular distributions, and total neutron yields per ion, were benchmarked by the PHITS, FLUKA, and MCNP model calculations. The default models in these codes agree the experimental data well at intermediate-to-large angles in the low-to-intermediate energy range. However, the physics models implemented in PHITS need further improvement for some particular nuclear interaction mechanisms, and this work can be an importance reference for future model development.
Wan, T.; Obayashi, Hironari; Sasa, Toshinobu
Nuclear Technology, 205(1-2), p.188 - 199, 2019/01
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Kondo, Hiroo*; Kanemura, Takuji*; Hirakawa, Yasushi; Furukawa, Tomohiro
Fusion Engineering and Design, 136(Part A), p.24 - 28, 2018/11
Times Cited Count：1 Percentile：0.01(Nuclear Science & Technology)In the IFMIF-EVEDA project, we designed and constructed the IFMIF-EVEDA Li Test Loop (ELTL), and we performed experiments to validate the stability of the Li target. This project required a diagnostic tool to be developed in order to examine the Li target; as such, we developed a unique laser-based method that we call the laser-probe method; this method combines a high-precision laser distance meter with a statistical data analysis method. Following the successful development of the laser-probe method, we proposes a long-distance-measurement of the laser probe method (long-distance LP method) as a diagnostics tool in off-beam conditions for IFMIF or the relevant neutron sources. In this study, the measurement uncertainty resulting from coherency of the laser in a long-distance-measurement has been verified by using stationary objects and a water jet simulating the liquid Li target.
Maekawa, Fujio; Transmutation Expeimental Facility Design Team
Plasma and Fusion Research (Internet), 13(Sp.1), p.2505045_1 - 2505045_4, 2018/05
The partitioning and transmutation (P-T) technology has promising potential for volume reduction and mitigation of degree of harmfulness of high-level radioactive waste. JAEA is promoting development of the P-T technology by using an accelerator driven system (ADS). To facilitate the development, we have a plan to construct the Transmutation Experimental Facility (TEF) as one of experimental facilities of J-PARC (Japan Proton Accelerator Research Complex). TEF consists of two facilities: the ADS Target Test Facility (TEF-T) and the Transmutation Physics Experimental Facility (TEF-P). Recent progress in design and R&D efforts toward construction of J-PARC TEF will be presented.
Iwamoto, Hiroki; Maekawa, Fujio; Matsuda, Hiroki; Meigo, Shinichiro
JAEA-Technology 2017-029, 39 Pages, 2018/01
JAEA-Technology-2017-029.pdf:2.68MB
Under an assumption that an incident of lead-bismuth eutectic (LBE) leak from an LBE circulation system occurred during a 250-kW beam operation, an estimation of radiation dose at the site boundary for the ADS Target Test Facility (TEF-T) in Transmutation Experimental Facility (TEF) of J-PARC was conducted using various conservative assumptions. As a result, the radiation dose at the site boundary was estimated to be about 660 Sv, which were dominated by mercury, noble gas, and iodine produced as spallation products from the LBE. Even though the incident scenario was made conservatively, it was shown that the estimated total dose was lower than the annual radiation dose due to natural sources, and the TEF-T has sufficient safety margin for the leak of radioactivity.
Lerendegui-Marco, J.*; Cort
s-Giraldo, M. A.*; Guerrero, C.*; Harada, Hideo; Kimura, Atsushi; n_TOF Collaboration*; 114 of others*
EPJ Web of Conferences, 146, p.03030_1 - 03030_4, 2017/09
Times Cited Count：0 Percentile：0.08(Nuclear Science & Technology)Wan, T.; Obayashi, Hironari; Sasa, Toshinobu
Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 13 Pages, 2017/09
Sasa, Toshinobu; Saito, Shigeru; Obayashi, Hironari; Sugawara, Takanori; Wan, T.; Yamaguchi, Kazushi*; Yoshimoto, Hidemitsu
NEA/CSNI/R(2017)2 (Internet), p.111 - 116, 2017/06
Japan Atomic Energy Agency (JAEA) proposes to reduce the environmental impact caused from high-level radioactive waste by using Accelerator-driven system (ADS). To realize ADS, JAEA plans to build the Transmutation Experimental Facility (TEF) within the framework of J-PARC project. For the JAEA-proposed ADS, lead-bismuth eutectic alloy (LBE) is adopted as a coolant for subcritical core and spallation target. By using TEF in J-PARC, we are planning to solve technical difficulties for LBE utilization by completion of the data for the design of ADS. The 250kW LBE spallation target will be located in TEF facility to prepare material irradiation database. Various R&Ds for important technologies required to build the facilities are investigated such as oxygen content control, instruments development, remote handling techniques for target maintenance, and spallation target design. The large scale LBE loops for 250kW target mock up and material corrosion studies are also manufactured and ready for various experiments. The latest status of 250kW LBE spallation target optimization will be described in the presentation.
Nuclear Transmutation Division, J-PARC Center
JAEA-Technology 2017-003, 539 Pages, 2017/03
JAEA-Technology-2017-003.pdf:59.1MB
JAEA is pursuing R&D on volume reduction and mitigation of degree of harmfulness of high-level radioactive waste based on the "Strategic Energy Plan" issued in April 2014. Construction of Transmutation Experimental Facility is under planning as one of the second phase facilities in the J-PARC program to promote R&D on the transmutation technology with using accelerator driven systems (ADS). The TEF consists of two facilities: ADS Target Test Facility (TEF-T) and Transmutation Physics Experimental Facility (TEF-P). Development of spallation target technology and study on target materials are to be conducted in TEF-T with impinging a high intensity proton beam on a lead-bismuth eutectic target. Whereas in TEF-P, by introducing a proton beam to minor actinide loaded subcritical cores, physical properties of the cores are to be studied, and operation experiences are to be acquired. This report summarizes results of technical design for construction of one of two TEF facilities, TEF-T.
Wan, T.; Obayashi, Hironari; Sasa, Toshinobu
Proceedings of 11th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-11) (USB Flash Drive), 12 Pages, 2016/10
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.
Kondo, Hiroo; Kanemura, Takuji; Furukawa, Tomohiro; Hirakawa, Yasushi; Wakai, Eiichi
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05
A liquid-Li free-surface stream is to serve as a beam target (Li target) for the IFMIF. As a major activity for the Li target in the IFMIF/EVEDA, the EVEDA Li test loop (ELTL) was constructed. This study focuses on cavitation-like acoustic noise in a conduit downstream of the Li target. This noise was detected by using acoustic-emission sensors. The intensity of the noise was examined versus cavitation number of the Li target. In addition, a time-frequency analysis for the acoustic signal was performed to characterize the noise. The results are as follows: (1) the intensity of the noise was increased as decreasing the cavitation number; (2) the noise was at first intermittent in a larger cavitation number, subsequently the noise became continuous as decreasing the cavitation number; (3) the noise consisted of a number of a high frequency acoustic emission which occurred in a short duration. For these results, we conclude that cavitation occurred in the downstream conduit.
Wakai, Eiichi; Ando, Masami; Okubo, Nariaki
Journal of Plasma and Fusion Research SERIES, Vol.11, p.104 - 112, 2015/03
The reduced-activation ferritic/martensitic (RAFM) steels for the fusion DEMO reactor have been developing from around the 1980s. RAFM steels are the first candidate materials for the first wall and blanket structure of fusion DEMO reactors, the target back-plate and the target assembly of IFMIF. In this study, two subjects had been examined and are summarized as below: (1) Effect of initial heat treatment on the microstructures and mechanical properties of RAFM steels, including irradiation damage, is very important to design the fusion DEMO reactors and also control the changes of mechanical properties after the irradiation. (2) Effects of He and H production on the microstructures and mechanical properties of RAFM steels, including irradiation damage, are essential in the evaluation of design of fusion DEMO reactor, and we have to check and evaluate them in Fusion irradiation environment like IFMIF.
