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Journal Articles

Experimental study on local damage to reinforced concrete panels subjected to oblique impact by projectiles

Okuda, Yukihiko; Nishida, Akemi; Kang, Z.; Tsubota, Haruji; Li, Y.

Journal of Nuclear Engineering and Radiation Science, 9(2), p.021801_1 - 021801_12, 2023/04

Most empirical formulas were proposed to evaluate the local damage to reinforced concrete (RC) structures based on impact tests conducted with a rigid projectile at an impact angle normal to the target structure. Only a few impact tests were performed involving a soft projectile. Therefore, in this study, we conducted a series of impact tests to evaluate the local damage to RC panels subjected to normal and oblique impacts by rigid and soft projectiles. This paper presents the test conditions, test equipment, test results, and obtained knowledge on local damage to RC panels subjected to normal and oblique impacts.

Journal Articles

ARKADIA; For the innovation of advanced nuclear reactor design

Ohshima, Hiroyuki; Asayama, Tai; Furukawa, Tomohiro; Tanaka, Masaaki; Uchibori, Akihiro; Takata, Takashi; Seki, Akiyuki; Enuma, Yasuhiro

Journal of Nuclear Engineering and Radiation Science, 9(2), p.025001_1 - 025001_12, 2023/04

This paper describes the outline and development plan for ARKADIA to transform advanced nuclear reactor design to meet expectations of a safe, economic, and sustainable carbon-free energy source. ARKADIA will realize Artificial Intelligence (AI)-aided integrated numerical analysis to offer the best possible solutions for the design and operation of a nuclear plant, including optimization of safety equipment. State-of-the-art numerical simulation technologies and a knowledge base that stores data and insights from past nuclear reactor development projects and R&D are integrated with AI. In the first phase of development, ARKADIA-Design and ARKADIA-Safety will be constructed individually, with the first target of sodium-cooled reactor. In a subsequent phase, everything will be integrated into a single entity applicable not only to advanced rectors with a variety of concepts, coolants, configurations, and output levels but also to existing light-water reactors.

Journal Articles

Feasibility study on reprocessing of HTGR spent fuel by existing PUREX plant and technology

Fukaya, Yuji; Goto, Minoru; Ohashi, Hirofumi

Annals of Nuclear Energy, 181, p.109534_1 - 109534_10, 2023/02

Feasibility of reprocessing of High Temperature Gas-cooled Reactor (HTGR) spent fuel by existing Plutonium Uranium Redox EXtraction (PUREX) plant and technology has been investigated. The spent fuel dissolved solution includes approximately 3 times amount of uranium-235 and 1.5 times amount of protonium because of the 3 times higher burnup compared with that of Light Water Reactor (LWR). Then, the heavy metal of the spent fuel is planned to be diluted to 3.1 times by depleted uranium to satisfy the limitation of Rokkasho Reprocessing Plant (RRP) plant. In the present study, recoverability of uranium and plutonium with the dilution is confirmed by a simulation with a reprocessing process calculation code. Moreover, the case without the dilution from the economic perspective is investigated. As a result, the feasibility is confirmed without the dilution, and it is expected that the reprocessed amount is reduced to 1/3 compared with a diluted case even though the facility should be optimized from the perspective of mass flow and criticality.

Journal Articles

A Quantitative method of eutectic reaction study between boron carbide and stainless steel

Hong, Z.*; Pellegrini, M.*; Erkan, N.*; Liao, H.*; Yang, H.*; Yamano, Hidemasa; Okamoto, Koji*

Annals of Nuclear Energy, 180, p.109462_1 - 109462_9, 2023/01

A series of experiments were conducted using B$$_{4}$$C material and SUS304 tubes as a simulant of the real control rods. Reaction rate constant data in the 1450K-1500K range were obtained, and are consistent with the reference values. The reaction layer microstructure observation and the associated chemical composition analysis were also carried onto the experiment samples.

Journal Articles

Difference in expansion and dehydration behaviors between NH$$_4$$- and K-montmorillonite

Kawakita, Ryohei; Saito, Akito*; Sakuma, Hiroshi*; Anraku, Sohtaro; Kikuchi, Ryosuke*; Otake, Tsubasa*; Sato, Tsutomu*

Applied Clay Science, 231, p.106722_1 - 106722_7, 2023/01

Journal Articles

Fatigue crack non-propagation behavior of a gradient steel structure from induction hardened railway axles

Zhang, H.*; Wu, S. C.*; Ao, N.*; Zhang, J. W.*; Li, H.*; Zhou, L.*; Xu, P. G.; Su, Y. H.

International Journal of Fatigue, 166, p.107296_1 - 107296_11, 2023/01

Journal Articles

Stress partitioning between bcc and cementite phases discussed from phase stress and dislocation density in martensite steels

Tsuchida, Noriyuki*; Ueji, Rintaro*; Gong, W.; Kawasaki, Takuro; Harjo, S.

Scripta Materialia, 222, p.115002_1 - 115002_6, 2023/01

 Times Cited Count:0

Journal Articles

Improvement of JASMINE code for ex-vessel molten core coolability in BWR

Matsumoto, Toshinori; Kawabe, Ryuhei*; Iwasawa, Yuzuru; Sugiyama, Tomoyuki; Maruyama, Yu

Annals of Nuclear Energy, 178, p.109348_1 - 109348_13, 2022/12

The Japan Atomic Energy Agency extended the applicability of their fuel-coolant interaction analysis code JASMINE to simulate the relevant phenomena of molten core in a severe accident. In order to evaluate the total coolability, it is necessary to know the mass fraction of particle, agglomerated and cake debris and the final geometry at the cavity bottom. An agglomeration model that considers the fusion of hot particles on the cavity floor was implemented in the JASMINE code. Another improvement is introduction of the melt spreading model based on the shallow water equation with consideration of crust formation at the melt surface. For optimization of adjusting parameters, we referred data from the agglomeration experiment DEFOR-A and the under-water spreading experiment PULiMS conducted by KTH in Sweden. The JASMINE analyses reproduced the most of the experimental results well with the common parameter set, suggesting that the primary phenomena are appropriately modelled.

Journal Articles

Accurate and precise measurement of uranium content in uranium trioxide by gravimetry; Comparison with isotope dilution mass spectrometry and its uncertainty estimation

Yamamoto, Masahiko; Horigome, Kazushi; Kuno, Takehiko

Applied Radiation and Isotopes, 190, p.110460_1 - 110460_7, 2022/12

 Times Cited Count:0

Gravimetric measurement of U content in UO$$_{3}$$ with ignition in the air has been investigated. The ignition temperature, ignition time and aliquot sample mass are optimized as 900$$^{circ}$$C, 60 minutes, and 1 g, respectively. The method is validated by IDMS with uncertainty estimation. The obtained result by gravimetry is 0.78236$$pm$$0.00051 g/g (k=2) and agreed with IDMS value within its uncertainty. It has been found that U in UO$$_{3}$$ can be measured accurately and precisely by gravimetry.

Journal Articles

Evaluation of doped potassium concentrations in stacked two-Layer graphene using real-time XPS

Ogawa, Shuichi*; Tsuda, Yasutaka; Sakamoto, Tetsuya*; Okigawa, Yuki*; Masuzawa, Tomoaki*; Yoshigoe, Akitaka; Abukawa, Tadashi*; Yamada, Takatoshi*

Applied Surface Science, 605, p.154748_1 - 154748_6, 2022/12

 Times Cited Count:0

Immersion of graphene in KOH solution improves its mobility on SiO$$_{2}$$/Si wafers. This is thought to be due to electron doping by modification with K atoms, but the K atom concentration C$$_{K}$$ in the graphene has not been clarified yet. In this study, the C$$_{K}$$ was determined by XPS analysis using high-brilliance synchrotron radiation. The time evolution of C$$_{K}$$ was determined by real-time observation, and the C$$_{K}$$ before irradiation of synchrotron radiation was estimated to be 0.94%. The C 1s spectrum shifted to the low binding energy side with the desorption of K atoms. This indicates that the electron doping concentration into graphene is decreasing, and it is experimentally confirmed that K atoms inject electrons into graphene.

Journal Articles

Thermodynamic analysis for solidification path of simulated ex-vessel corium

Sato, Takumi; Nagae, Yuji; Kurata, Masaki; Quaini, A.*; Gu$'e$neau, C.*

CALPHAD; Computer Coupling of Phase Diagrams and Thermochemistry, 79, p.102481_1 - 102481_11, 2022/12

 Times Cited Count:0

Journal Articles

Si-addition contributes to overcoming the strength-ductility trade-off in high-entropy alloys

Wei, D.*; Gong, W.; Tsuru, Tomohito; Lobzenko, I.; Li, X.*; Harjo, S.; Kawasaki, Takuro; Do, H.-S.*; Bae, J. W.*; Wagner, C.*; et al.

International Journal of Plasticity, 159, p.103443_1 - 103443_18, 2022/12

 Times Cited Count:0

Journal Articles

Third international challenge to model the medium- to long-range transport of radioxenon to four Comprehensive Nuclear-Test-Ban Treaty monitoring stations

Maurer, C.*; Galmarini, S.*; Solazzo, E.*; Ku$'s$mierczyk-Michulec, J.*; Bar$'e$, J.*; Kalinowski, M.*; Schoeppner, M.*; Bourgouin, P.*; Crawford, A.*; Stein, A.*; et al.

Journal of Environmental Radioactivity, 255, p.106968_1 - 106968_27, 2022/12

After performing multi-model exercises in 2015 and 2016, a comprehensive Xe-133 atmospheric transport modeling challenge was organized in 2019. For evaluation measured samples for the same time frame were gathered from four International Monitoring System stations located in Europe and North America with overall considerable influence of IRE and/or CNL emissions. As a lesion learnt from the 2nd ATM-Challenge participants were prompted to work with controlled and harmonized model set ups to make runs more comparable, but also to increase diversity. Effects of transport errors, not properly characterized remaining emitters and long IMS sampling times (12 to 24 hours) undoubtedly interfere with the effect of high-quality IRE and CNL stack data. An ensemble based on a few arbitrary submissions is good enough to forecast the Xe-133 background at the stations investigated. The effective ensemble size is below five.

Journal Articles

Numerical reproduction of the seasonal variation in dissolved uranium in Lake Biwa

Saito, Tatsuo; Yamazawa, Hiromi*; Mochizuki, Akihito

Journal of Environmental Radioactivity, 255, p.107035_1 - 107035_14, 2022/12

The seasonal variation of dissolved U (DU) in Lake Biwa was reproduced by the following model and parameter research. The introduced models are the water-DU mass balance, and the ion exchange between UO$$_{2}$$$$^{2+}$$ and H$$^{+}$$ on the lakeshore soil. The optimized parameters were the CEC of the lakeshore, TU as the sum of DU and AU (soil adsorbed U), kads and kdes as the first order reaction rate coefficients during rapid soil adsorption and desorption of U, respectively. Tabulated by the chemical equilibria constituting DU and analyzed the contribution of each chemical species, it is shown that the seasonal variation of DU is caused by the seasonal variation of pH. A correction to the ion-exchange equilibrium to shift to first order rate reaction only when the daily AU ratio increased above kads or decreased below kdes, improved the reproducibility of DU measurements and reproduced the delay of the DU peak from the pH peak.

Journal Articles

Strengthening of high-entropy alloys via modulation of cryo-pre-straining-induced defects

Wei, D.*; Gong, W.; Wang, L.*; Tang, B.*; Kawasaki, Takuro; Harjo, S.; Kato, Hidemi*

Journal of Materials Science & Technology, 129, p.251 - 260, 2022/12

 Times Cited Count:5 Percentile:94.07(Materials Science, Multidisciplinary)

Journal Articles

Laser heating induced spatial homogenization of phase separated Na$$_{2}$$O-B$$_{2}$$O$$_{3}$$-SiO$$_{2}$$ glass plate with bearing NiO for heat center and structural probe

Tomita, Kana*; Kishi, Tetsuo*; Matsumura, Daiju; Yano, Tetsuji*

Journal of Non-Crystalline Solids, 597, p.121891_1 - 121891_10, 2022/12

 Times Cited Count:0

Journal Articles

Effect of nitrogen concentration on creep strength and microstructure of 9Cr-ODS ferritic/martensitic steel

Oka, Hiroshi*; Tanno, Takashi; Yano, Yasuhide; Otsuka, Satoshi; Kaito, Takeji; Hashimoto, Naoyuki*

Journal of Nuclear Materials, 572, p.154032_1 - 154032_8, 2022/12

9Cr oxide dispersion strengthened steels with slightly different nitrogen concentrations (0.0034 - 0.029 wt%) were prepared and their creep property at 973 K was investigated with microstructural characterization before and after the creep test. The creep strength decreased significantly as the nitrogen concentration increased. Microstructural observation revealed that, in the higher nitrogen concentration specimen, coarse Y-rich inclusions were found along the boundary between transformed ferrite region and residual ferrite region. The solubility difference of nitrogen in $$alpha$$ and $$gamma$$ phase would induce the localized increment of nitrogen concentration in the boundary region during the austenitizing process, resulting in the thermodynamic destabilization and subsequent coarsening of the dispersed oxide particles. The rows of creep voids were found near the rupture part of the crept specimen, suggesting that the coarse inclusions were the starting point of creep void formation and the subsequent premature fracture.

Journal Articles

Stability of allowable flaw angles for high toughness ductile pipes subjected to bending stress in the ASME Code Section XI

Hasegawa, Kunio; Strnadel, B.*; Li, Y.; Lacroix, V.*

Journal of Pressure Vessel Technology, 144(6), p.061202_1 - 061202_6, 2022/12

When pipe walls are thin, part-through flaws are easily develop into through-wall flaws, and the likelihood of coolant leakage is high. The ASEM Code Section XI provides final allowable flaw angles of through-wall flaw for thin-wall pipes. The final allowable angles are applied to pipes in order to maintain structural integrity if the part-through flaws become through-wall flaws. To ensure that this stability is compromised, plastic collapse stresses for through-wall flaws are combined with allowable stresses. However, the final allowable angles of through-wall flaws are not identified for thin-walled pipes. This paper compares plastic collapse stresses of through-wall flaws and allowable stresses of part-through flaws for pipes. The comparison of these stresses is used to derive the final allowable angles of through-wall flaws. The angles can be expressed either in the form of exact solutions or as conventional options that are appropriate for various service level conditions.

Journal Articles

Enhanced Spin-Orbit Coupling in a Correlated Metal

Kubo, Katsunori

Journal of the Physical Society of Japan, 91(12), p.124707_1 - 124707_7, 2022/12

Journal Articles

Study on evaluation method of kernel migration of TRISO fuel for High Temperature Gas-cooled Reactor

Fukaya, Yuji; Okita, Shoichiro; Sasaki, Koei; Ueta, Shohei; Goto, Minoru; Ohashi, Hirofumi; Yan, X.

Nuclear Engineering and Design, 399, p.112033_1 - 112033_9, 2022/12

Kernel migration of TRi-structural ISOtropic (TRISO) fuel for High Temperature Gas-cooled Reactor (HTGR) has been analyzed to investigate the potential dominating effects. Kernel migration is a major fuel failure mode and dominant to determine the lifetime of the fuel for High Temperature engineering Test Reactor (HTTR). However, this study shows that the result and reliability depend on the evaluation method. The evaluation method used in this study takes into account of actual distribution of Coated Fuel Particles (CFPs) and the resulting heterogeneous fuel temperature calculation with such distribution. The result shows that the Kernel Migration Rate (KMR) is predicted to be about 10% less compared with the most conservative evaluation.

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