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Kwon, Saerom*; Konno, Chikara; Honda, Shogo*; Kenjo, Shunsuke*; Sato, Satoshi*
Fusion Engineering and Design, 223, p.115548_1 - 115548_8, 2026/02
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)In order to evaluate the accuracy of the iron data in the latest nuclear data libraries (FENDL-3.2b, JENDL-5, ENDF/B-VIII.0 and JEFF-3.3) used in the fusion neutron source design, we performed their benchmark tests by using QST/TIARA iron experiment with quasi mono-energy neutrons of 40 and 65 MeV and JAEA/FNS iron experiment with DT neutrons. From the test results, we have found the following issues; (1) The calculation results with FENDL-3.2b underestimate the measured neutron fluxes of the continuous energy range (10-60 MeV) by a factor of 0.6 in the TIARA experiment with 65 MeV neutrons; (2) The calculation results with FENDL-3.2b tend to underestimate the measured neutron flux above 10 MeV by a factor of 0.8 at depth of 70 cm and overestimate the measured ones below 10 keV by a factor of 1.3 up to depth of 40 cm in the FNS experiment. We investigated those issues in detail and clarified their reasons.
Okutsu, Kenichi*; Yamashita, Takuma*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.
Fusion Engineering and Design, 170, p.112712_1 - 112712_4, 2021/09
Times Cited Count：5 Percentile：40.43(Nuclear Science & Technology)A muonic molecule which consists of two hydrogen isotope nuclei (deuteron (d) or tritium (t)) and a muon decays immediately via nuclear fusion and the muon will be released as a recycling muon, and start to find another hydrogen isotope nucleus. The reaction cycle continues until the muon ends up its lifetime of 2.2 
s. Since the muon does not participate in the nuclear reaction, the reaction is so called a muon catalyzed fusion (CF). The recycling muon has a particular kinetic energy (KE) of the muon molecular orbital when the nuclear reaction occurs. Since the KE is based on the unified atom limit where distance between two nuclei is zero. A precise few-body calculation estimating KE distribution (KED) is also in progress, which could be compared with the experimental results. In the present work, we observed recycling muons after CF reaction.
Yamashita, Takuma*; Okutsu, Kenichi*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.
Fusion Engineering and Design, 169, p.112580_1 - 112580_5, 2021/08
Times Cited Count：4 Percentile：32.90(Nuclear Science & Technology)A muon () having 207 times larger mass of electron and the same charge as the electron has been known to catalyze a nuclear fusion between deuteron (d) and triton (t). These two nuclei are bound by and form a muonic hydrogen molecular ion, dt. Due to the short inter-nuclear distance of dt, the nuclear fusion, d +t
+ n + 17.6 MeV, occurs inside the molecule. This reaction is called muon catalyzed fusion (CF). Recently, the interest on CF is renewed from the viewpoint of applications, such as a source of high-resolution muon beam and mono-energetic neutron beam. In this work, we report a time evolution calculation of CF in a two-layered hydrogen isotope target.
Kenzhina, I.*; Ishitsuka, Etsuo; Ho, H. Q.; Sakamoto, Naoki*; Okumura, Keisuke; Takemoto, Noriyuki; Chikhray, Y.*
Fusion Engineering and Design, 164, p.112181_1 - 112181_5, 2021/03
Tritium release into the primary coolant during operation of the JMTR (Japan Materials Testing Reactor) and the JRR-3M (Japan Research Reactor-3M) had been studied. It is found that the recoil release by 
Li(n
,
)
H reaction, which comes from a chain reaction of beryllium neutron reflectors, is dominant. To prevent tritium recoil release, the surface area of beryllium neutron reflectors needs to be minimum in the core design and/or be shielded with other material. In this paper, as the feasibility study of the tritium recoil barrier for the beryllium neutron reflectors, various materials such as Al, Ti, V, Ni, and Zr were evaluated from the viewpoint of the thickness of barriers, activities after long-term operations, and effects on the reactivities. From the results of evaluations, Al would be a suitable candidate as the tritium recoil barrier for the beryllium neutron reflectors.
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：7.67(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.
Kwon, Saerom*; Konno, Chikara; Ota, Masayuki*; Ochiai, Kentaro*; Sato, Satoshi*; Kasugai, Atsushi*
Fusion Engineering and Design, 144, p.209 - 214, 2019/07
Times Cited Count：5 Percentile：36.41(Nuclear Science & Technology)We performed a TENDL-2017 benchmark test with iron shielding experiments by using 40 and 65 MeV neutrons, in order to verify a nuclear data library above 20 MeV for neutronics analyses of A-FNS. We found out that the calculated neutron spectra with TENDL-2017 unnaturally increased near 30 MeV. We figured out that incorrect secondary neutron spectrum data in 
Fe, 
Fe and 
Fe at 30 MeV caused the increase of the neutron flux. Similar problems occurred in a lot of nuclei of TENDL-2017, TENDL-2015 and FENDL-3.1d from TENDL-2010 and TENDL-2011.
Kondo, Hiroo*; Kanemura, Takuji*; Hirakawa, Yasushi; Furukawa, Tomohiro
Fusion Engineering and Design, 136(Part A), p.24 - 28, 2018/11
Times Cited Count：3 Percentile：23.28(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.
Goto, Minoru; Okumura, Keisuke; Nakagawa, Shigeaki; Inaba, Yoshitomo; Matsuura, Hideaki*; Nakaya, Hiroyuki*; Katayama, Kazunari*
Fusion Engineering and Design, 136(Part A), p.357 - 361, 2018/11
Times Cited Count：12 Percentile：63.62(Nuclear Science & Technology)A High Temperature Gas-cooled Reactor (HTGR) is proposed as a tritium production device, which has the potential to produce a large amount of tritium using Li(n,)T reaction. In the HTGR design, generally, boron is loaded into the core as a burnable poison to suppress excess reactivity. In this study, lithium is loaded into the HTGR core instead of boron and is used as a burnable poison aiming to produce thermal energy and tritium simultaneously. The nuclear characteristics and the fuel temperature were calculated to confirm the feasibility of the lithium-loaded HTGR. It was shown that the calculation results satisfied the design requirements and hence the feasibility was confirmed for the lithium-loaded HTGR, which produce thermal energy and tritium.
Saito, Makiko; Kozaka, Hiroshi; Maruyama, Takahito; Noguchi, Yuto; Takeda, Nobukazu; Kakudate, Satoshi; 1 of others*
Fusion Engineering and Design, 124, p.542 - 547, 2017/11
Times Cited Count：6 Percentile：42.72(Nuclear Science & Technology)Tojo, Hiroshi; Hatae, Takaki; Hamano, Takashi; Itami, Kiyoshi
Fusion Engineering and Design, 123, p.678 - 681, 2017/11
Times Cited Count：5 Percentile：36.56(Nuclear Science & Technology)Kwon, Saerom*; Ota, Masayuki*; Sato, Satoshi*; Konno, Chikara; Ochiai, Kentaro*
Fusion Engineering and Design, 124, p.1161 - 1164, 2017/11
Times Cited Count：3 Percentile：23.14(Nuclear Science & Technology)Copper is used as a material for superconducting coil in magnetic confinement fusion reactor and for accelerator-driven neutron source such as IFMIF. In our previous copper benchmark experiment, we had pointed out that the elastic scattering and capture reaction data of the copper had included some problems in the resonance region, which had caused a large underestimation of reaction rates of non-threshold reactions. In order to corroborate this issue, we carried out a new benchmark experiment on copper with graphite in the neutron field with more low energy neutrons. We measured reaction rates using the activation foils. We analyzed the experiment with MCNP code and the latest nuclear data libraries. As a result, the calculated reaction rates related to low energy neutrons, still excessively underestimated the measured ones as in the previous benchmark experiment. We also tested the nuclear data of copper modified in the previous study, where the elastic scattering and capture reaction cross section of copper. Then the calculated reaction rates with the modified copper nuclear data reproduced the measured ones well. It was revealed that the modification of the specific cross sections had been sufficient in the neutron field with more low energy neutrons.
Ota, Masayuki*; Kwon, Saerom*; Sato, Satoshi*; Konno, Chikara; Ochiai, Kentaro*
Fusion Engineering and Design, 114, p.127 - 130, 2017/01
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)A new fusion neutron source is now under consideration in Japan. Type 316L stainless steel (SUS316L) which is a structural material of the target-system contains a few percent of molybdenum. In our previous benchmark experiment on molybdenum at JAEA/FNS, we found problems of the cross section data above a few hundred eV in Mo. We perform a new benchmark experiment on Mo with graphite in order to validate the Mo data in the lower energy region. Several dosimetry reaction rates and fission rates are measured in the assembly and compared with the calculated values with the Monte-Carlo transport code MCNP5-1.40 and the recent nuclear data libraries. It is suggested that the (n,
) cross section of 
Mo is underestimated in the tail region below the large resonance at 45 eV in the recent nuclear data libraries.
Yamanishi, Toshihiko; Asakura, Nobuyuki; Tobita, Kenji; Ohira, Shigeru; Federici, G.*; Heidinger, R.*; Knaster, J.*; Clement, S.*; Nakajima, Noriyasu*
Fusion Engineering and Design, 109-111(Part B), p.1272 - 1279, 2016/11
Times Cited Count：3 Percentile：23.90(Nuclear Science & Technology)In the Broader Approach (BA) activities, the International Fusion Energy Research Center (IFERC) project, the International Fusion Materials Irradiation Facility/Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) project and the Satellite Tokamak project are implemented aiming at early realization of the fusion energy from 2007 to 2017. DEMO design activity has been conducted as joint work between EU and Japan, in order to establish DEMO design bases. In the DEMO R&D activities, following five R&D tasks related blanket materials and technology are carried out; R&D on RAFM steels as structural material, SiCf/SiC composites as a flow channel insert material and/or alternative structural material, advanced tritium breeders and neutron multipliers, and tritium technology relevant to the DEMO operational condition. Regarding the IFMIF/EVEDA Project, the validation test using EVEDA Lithium Test Loop (ELTL) was completed successfully in 2014 the end of October. Installation of the LIPAc injector and auxiliary equipment delivered by F4E has been done and the first proton beam extraction was successfully performed in November 2014.
Kato, Taichiro; Ohata, Mitsuru*; Nogami, Shuhei*; Tanigawa, Hiroyasu
Fusion Engineering and Design, 109-111(Part B), p.1631 - 1636, 2016/11
Times Cited Count：13 Percentile：70.07(Nuclear Science & Technology)Plastic deformability of material shows general tendency to decrease due to become hard and brittle. Also, the plastic deformability tends to decrease as the stress triaxiality of a parameter to evaluate the magnitude of plastic constraint increases. Therefore, it is necessary to accurately understand the ductility loss limit of RAFM in order to conduct the structural design assessment of a fusion reactor demo blanket. In this study, plastic deformability of RAFM was evaluated the impacts of stress triaxiality on variation of tensile specimen shape and testing conditions. In the results, the fracture was defined as not the point of macro-crack but that of micro-crack. It was confirmed that the true strain rate significantly increases in the vicinity of the point of micro-crack. The relationships between the fracture ductile and stress triaxiality of the full size tensile specimen and the miniature size one were shown on the single curve regardless of the specimen size.
Ota, Masayuki; Sato, Satoshi; Kwon, Saerom; Ochiai, Kentaro; Konno, Chikara
Fusion Engineering and Design, 109-111(Part B), p.1644 - 1648, 2016/11
Times Cited Count：3 Percentile：23.90(Nuclear Science & Technology)An integral experiment on molybdenum is performed with a DT neutron source at JAEA/FNS. A Mo assembly is covered with lithium oxide blocks in order to reduce background neutrons inside the assembly. Several reaction rates and fission rates are measured along the central axis inside the assembly and compared with calculated ones with the Monte Carlo transport code MCNP5-1.40 and recent nuclear data libraries of ENDF/B-VII.1, JENDL-4.0, and JEFF-3.2. The calculated results generally show underestimation. From a detail analysis, it is concluded that the (n,2n) cross section data for all the Mo stable isotopes in JEFF-3.2 are more suitable than those in JENDF-4.0 and the (n,) cross section data for all the Mo stable isotopes except for Mo-98 in JENDL-4.0 are overestimated.
Shirai, Hiroshi; Barabaschi, P.*; Kamada, Yutaka; JT-60SA Team
Fusion Engineering and Design, 109-111(Part B), p.1701 - 1708, 2016/11
Times Cited Count：24 Percentile：86.97(Nuclear Science & Technology)The JT-60SA Project has shown steady progress toward the first plasma in 2019. JT-60SA is a superconducting tokamak designed to operate in the break-even conditions for a long pulse duration with a maximum plasma current of 5.5 MA. Design and fabrication of JT-60SA components shared by EU and Japan started in 2007. Assembly in the torus hall started in January 2013, and welding work of the vacuum vessel sectors is currently on going on the cryostat base. Other components such as TF coils, PF coils, power supplies, cryogenic system, cryostat vessel, thermal shields and so forth were or are being delivered to Naka site for installation, assembly and commissioning. This paper gives technical progress on fabrication, installation and assembly of tokamak components and ancillary systems, as well as progress of JT-60SA Research Plan being developed jointly by EU and Japanese fusion communities.
Kim, Jae-Hwan; Nakamichi, Masaru
Fusion Engineering and Design, 109-111(Part B), p.1764 - 1768, 2016/11
Times Cited Count：17 Percentile：76.53(Nuclear Science & Technology)Sakasegawa, Hideo; Tanigawa, Hiroyasu
Fusion Engineering and Design, 109-111(Part B), p.1724 - 1727, 2016/11
Times Cited Count：13 Percentile：70.07(Nuclear Science & Technology)Fusion DEMO reactor requires over 11,000 tons of reduced activation ferritic/martensitic steel and it is important to develop the manufacturing technology for producing large-scale components of DEMO blanket with appropriate mechanical properties. In this work, we studied mechanical properties of ferritic/martensitic steel F82H plates with different thicknesses. This is because mechanical properties are generally degraded with increasing production volume and size. As the result, their homogeneity and anisotropy were not significant. However, mass effect was found in their Charpy impact property with increasing plate thickness, i.e. the ductile brittle transition temperature (DBTT) of a 100 mm thick plate was higher than those of the other plates, but its DBTT was still lower than 0
C and comparable to the former heats.
Hoshino, Tsuyoshi; Edao, Yuki; Kawamura, Yoshinori; Ochiai, Kentaro
Fusion Engineering and Design, 109-111(Part B), p.1114 - 1118, 2016/11
Times Cited Count：38 Percentile：94.49(Nuclear Science & Technology)Li
TiO
with excess Li (Li
TiO
) has been developed as an advanced tritium breeder. Considering the tritium release characteristics, the optimum grain size of pebble is less than 5 m. Therefore, the pebble fabrication by using emulsion method was carried out to obtain the target value. Calcined LiTiO pebbles were sintered under vacuum and subsequent 1% H-He atmosphere. The average grain size of the sintered pebbles was less than 5 m. Furthermore, the tritium release properties of the pebbles are required for DEMO blanket design. In the present study, an evaluation of the tritium release properties of the pebbles was performed by DT neutron irradiation. The LiTiO pebbles exhibited good tritium release properties similar to the LiTiO pebbles. In particular, the released amount of HT gas for easier tritium handling was higher than that of HTO water.
Nakamichi, Masaru; Kim, Jae-Hwan; Ochiai, Kentaro
Fusion Engineering and Design, 109-111(Part B), p.1719 - 1723, 2016/11
Times Cited Count：14 Percentile：72.42(Nuclear Science & Technology)