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JAEA Reports

Verification of the tables for control rods calibration at NSRR

Motome, Yuiko; Agake, Toshiki; Yanagisawa, Hiroshi

JAEA-Technology 2024-015, 30 Pages, 2025/01

JAEA-Technology-2024-015.pdf:1.36MB

The tables for calibration of control rods were verified, which is used positive period method and improved rod drop method of periodic inspection at Nuclear Safety Research Reactor (NSRR). Those tables are "DOUBLING TIME-REACTIVITY" and "DECAY OF NEUTRON FLUX AFTER INSTANTANEOUS REDUCTION OF REACTIVITY". They are prepared around 1975. Since those tables do not clearly express source of values and records of data used in calculations, the authors verified those tables again. For the verification, the tables were reproduced as follows. For the positive period method, the relationship between the period and reactivity was analytically evaluated by using the inhour equation with NSRR's parameters. For the improved rod drop method, the ratios of neutron flux after the rod drop with parameters of negative reactivities was calculated using the EUREKA- 2 code. As a result, the values described in the tables well agree with those by the present evaluation because it is confirmed that standard deviations of the differences in the value by between the present evaluation and the tables are less than 0.035%. For this reason, it is verified that these tables are valid in the practical use for NSRR operations.

Journal Articles

$$mu$$SR studies on copper minerals

Fujihara, Masayoshi; Okabe, Hirotaka*; Koda, Akihiro*

Interactions (Internet), 245(1), p.13_1 - 13_6, 2024/12

Quantum states are difficult to observe experimentally. In addition, ideal model materials have not been found for some of the lattice systems in which exotic quantum states are predicted to be realized. Numerous candidates for low-dimensional quantum magnets are hidden in copper minerals, and the number of candidates is increasing every year. We succeeded to synthesize seven copper minerals by imitating the environment where they are discovered and reported their quantum states. The properties of pulsed muons are very suitable for investigating the spin state of artificial copper minerals.

Journal Articles

Thinning behavior of solid boron carbide immersed in molten stainless steel for core disruptive accident of sodium-cooled fast reactor

Emura, Yuki; Takai, Toshihide; Kikuchi, Shin; Kamiyama, Kenji; Yamano, Hidemasa; Yokoyama, Hiroki*; Sakamoto, Kan*

Journal of Nuclear Science and Technology, 61(7), p.911 - 920, 2024/07

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

Journal Articles

Numerical simulation of accidents involving core damage with integrative severe accident analysis code, SPECTRA

Ishida, Shinya; Uchibori, Akihiro; Okano, Yasushi

Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2024/06

no abstracts in English

Journal Articles

Influence of temperature on stress corrosion cracking susceptibility of carbon steel in sodium hydrogen carbonate aqueous solution assuming upper limit of carbonate concentration in geological disposal environment

Takahashi, Rieko*; Taniguchi, Naoki

Zairyo To Kankyo, 73(6), p.153 - 163, 2024/06

Carbon steel is one of the candidate materials for overpacks in geological disposal of high-level radioactive waste, and is known to susceptible to stress corrosion cracking(SCC) depending on the condition in carbonate environment. In order to understand the influence of temperature on the SCC susceptibility of carbon steel, slow strain rate test (SSRT) of rolled steel were performed in NaHCO$$_{3}$$ aqueous solution with varying temperature in the range of 303-393K for conditions of 0.1-0.5 mol/dm$$^{3}$$, which is assumed to be the upper limit of carbonate concentration in groundwater in a geological disposal environment. As the results, no obvious influence of temperature on mechanical properties such as fracture strain ratio and reduction area ratio were observed, but SCC susceptibility based on SCC fracture ratio increased at relatively low temperatures of 303K and 323K. It was suggested that the reason for the higher SCC sensitivity at lower temperatures was due to slower repassivation at lower temperatures. Regarding the type of SCC, intergranular SCC was dominant at low temperatures and tended to transition to intergranular SCC at higher temperatures. Transgranular SCC tended to be observed at lower potentials than those at which intergranular SCC was observed.

Journal Articles

Numerical study of initiating phase of core disruptive accident in small sodium-cooled fast reactors with negative void reactivity

Ishida, Shinya; Fukano, Yoshitaka; Tobita, Yoshiharu; Okano, Yasushi

Journal of Nuclear Science and Technology, 61(5), p.582 - 594, 2024/05

 Times Cited Count:1 Percentile:34.39(Nuclear Science & Technology)

Journal Articles

Impact of irradiation side on muon-induced single-event upsets in 65-nm Bulk SRAMs

Deng, Y.*; Watanabe, Yukinobu*; Manabe, Seiya*; Liao, W.*; Hashimoto, Masanori*; Abe, Shinichiro; Tampo, Motonobu*; Miyake, Yasuhiro*

IEEE Transactions on Nuclear Science, 71(4, Part 2), p.912 - 920, 2024/04

 Times Cited Count:0 Percentile:0.00(Engineering, Electrical & Electronic)

With the miniaturization of semiconductors and the decrease in operating voltage, there is a growing interest and discussion in whether the muons in cosmic rays may be the source of single event upsets (SEUs). In the case of neutron-induced SEUs, it was reported that the irradiation side has the impact on SEU cross sections. Here, to investigate the impact of irradiation direction on muon-induced SEUs, we have measured and simulate muon-induced SEUs in 65-nm bulk SRAMs with different muon irradiation directions. It was found that the peak SEU cross section for the package side irradiation is about twice large as that for the board side irradiation. We also revealed that the difference in observed SEU cross sections between the package side and the board side irradiation is caused by differences in energy straggling due to changes in penetration depth depending on the incident direction.

Journal Articles

Attempts to estimate the amount of contamination by Cs and Sr in cracked concrete considering realistic contamination conditions

Yamada, Kazuo*; Hokora, Hideyuki*; Maruyama, Ippei*; Aihara, Haruka; Tomita, Sayuri*; Tojo, Yasumasa*; Shibuya, Kazutoshi*; Hosokawa, Yoshifumi*; Igarashi, Go*; Koma, Yoshikazu

Proceedings of Waste Management Symposia 2024 (WM2024) (Internet), 7 Pages, 2024/03

Journal Articles

Accelerator mass spectrometry of $$^{90}$$Sr in environmental samples utilizing laser photo-detachment

Honda, Maki; Martschini, M.*; Marchhart, O.*; Steier, P.*; Golser, R.*; Sakaguchi, Aya*

Hoshasen (Internet), 48(4), p.130 - 136, 2024/02

Strontium-90 ($$^{90}$$Sr, 28.9 years) is a key fission product nuclide in internal dose assessment because it accumulates in bones and teeth in the body, causing health problems. Therefore, it is essential to know the distribution of $$^{90}$$Sr in the environment and its temporal variation ($$^{90}$$Sr enrichment in biota), which requires efficient analysis of many environmental samples. An analysis of environmental samples with known $$^{90}$$Sr concentrations conducted with the 3 MV AMS facility (VERA: Vienna Environmental Research Accelerator) at the University of Vienna, Austria, towards the practical application of $$^{90}$$Sr AMS, the results of which are detailed in this paper. In this study, the validity of the AMS method was demonstrated by analyzing environmental samples with known $$^{90}$$Sr concentrations (IAEA-447, IAEA-A-12, and IAEA-TEL-2015-03 sample 5: 1 dry-g each). The chemical separation developed in this study takes approximately two days and is a more straightforward procedure than conventional $$beta$$-ray detection methods. The $$^{90}$$Sr measurements were conducted on the AMS system combined with the Ion Laser InterAction Mass Spectrometry (ILIAMS) system. The AMS method achieved a limit of detection $$<$$0.1 mBq ($$<$$ 1.3$$times$$10$$^{5}$$ atoms) for $$^{90}$$Sr, which is 1/30th of typical $$beta$$-ray detection. As a result of the lower detection limit, the AMS method allows $$^{90}$$Sr quantification with smaller sample volumes. For example, a Japanese freshwater sample with a $$^{90}$$Sr concentration of 4 mBq/L requires a sample volume of 5 liter

Journal Articles

Application of the Y separation method using DGA resin for the measurement of $$^{90}$$Sr in human teeth and marine fish bones

Koarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Terashima, Motoki

KEK Proceedings 2023-2, p.155 - 160, 2023/11

In this presentation, we report the results of the application of the Y-separation method using DGA resin to the determination of $$^{90}$$Sr in human teeth and seawater fish bones.

Journal Articles

Benchmark analyses on control rod worths of TRIGA reactor modeled in the ICSBEP handbook using continuous-energy Monte Carlo code MVP version 3

Yanagisawa, Hiroshi; Umeda, Miki; Motome, Yuiko; Murao, Hiroyuki

Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 10 Pages, 2023/10

The benchmark analyses on the TRIGA reactor of the IEU-COMP-THERM-013 (ICT-013) in the ICSBEP handbook using the MVP version 3 code were carried out with the Japanese, US and European nuclear data libraries, including JENDL-5. The analyses on effective neutron multiplication factors (k$$_{eff}$$'s) were also performed for another TRIGA reactor defined in the ICT-003 as well as the ICT-013. As a result, it is confirmed that the calculated k$$_{eff}$$'s vary in the range of 0.8% with the libraries. The results also suggest that there might be unknown bias in the ICT-013 for the calculated k$$_{eff}$$'s. For the analyses on the control rod worths of the ICT-013, it is confirmed that differences in the worths among the libraries become smaller than those in k$$_{eff}$$'s. Most of the errors involved in k$$_{eff}$$'s are considered to be cancelled in the calculation of the worths since the worths are obtained by subtraction of the reciprocals of two sorts of k$$_{eff}$$'s. The differences in the worths by between the benchmark and alternative methods defined in the ICT-013 were tried to be examined from the aspect of the differences in horizontal flux distributions by between those methods. It is confirmed that the differences in the worths for two shim control rods, which are fully withdrawn at a delayed critical state, are well understood by that attempt, but on the other hand the differences are not sufficiently explained for a regulating control rod, which is partially inserted to attain delayed criticality.

Journal Articles

Study on the uptake of $$^{90}$$Sr and $$^{137}$$Cs into wild animals after the Fukushima Daiichi Nuclear Power Plant accident using hard tissue as an indicator

Koarai, Kazuma

Hosha Kagaku, (47), p.24 - 27, 2023/03

Ca-based tissues, such as teeth and bones, are called hard tissues. Sr is incorporated into the tooth during calcification. Once incorporated, it remains until the tooth falls out. Therefore, $$^{90}$$Sr in teeth recorded $$^{90}$$Sr contamination by the 1F accident in the environment during the formation period. The article presents current research findings.

JAEA Reports

Nuclear criticality benchmark analyses on TRIGA-type reactor systems by using continuous-energy Monte Carlo code MVP with JENDL-5

Yanagisawa, Hiroshi; Umeda, Miki; Motome, Yuiko; Murao, Hiroyuki

JAEA-Technology 2022-030, 80 Pages, 2023/02

JAEA-Technology-2022-030.pdf:2.57MB
JAEA-Technology-2022-030(errata).pdf:0.11MB

Nuclear criticality benchmark analyses were carried out for TRIGA-type reactor systems in which uranium-zirconium hydride fuel rods are loaded by using the continuous-energy Monte Carlo code MVP with the evaluated nuclear data library JENDL-5. The analyses cover two sorts of benchmark data, the IEU-COMP-THERM-003 and IEU-COMP-THERM-013 in the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook, and effective neutron multiplication factors, reactivity worths for control rods etc. were calculated by JENDL-5 in comparison with those by the previous version of JENDL. As the results, it was confirmed that the effective neutron multiplication factors obtained by JENDL-5 were 0.4 to 0.6% greater than those by JENDL-4.0, and that there were no significant differences in the calculated reactivity worths by between JENDL-5 and JENDL-4.0. Those results are considered to be helpful for the confirmation of calculation accuracy in the analyses on NSRR control rod worths, which are planned in the future.

Journal Articles

Spin gap in the weakly interacting quantum spin chain antiferromagnet KCuPO$$_{4}$$$$cdot$$H$$_{2}$$O

Fujihara, Masayoshi; Hagihara, Masato; Morita, Katsuhiro*; Murai, Naoki; Koda, Akihiro*; Okabe, Hirotaka*; Mitsuda, Setsuo*

Physical Review B, 107(5), p.054435_1 - 054435_8, 2023/02

 Times Cited Count:1 Percentile:0.00(Materials Science, Multidisciplinary)

The $$S$$ = 1/2 Heisenberg linear chain antiferromagnet is the simplest spin model; nevertheless it serves as a platform for various quantum many-body phenomena. Here, we report the magnetic behavior of a quasi-one-dimensional antiferromagnet KCuPO$$_{4}$$$$cdot$$H$$_{2}$$O. A long-range commensurate antiferromagnetic order with ordered moment 0.31(1) $$mu_{rm{B}}$$ per spin occurs at $$T_{rm{N}}$$ = 11.7(1) K. Above $$T_{rm{N}}$$, the inelastic neutron excitation is characterized by a two spinon continuum. The intrachain interaction $$J$$ and interchain interaction $$|J'|$$ are estimated to be 172 K and 4.25(4) K, respectively; thus the ratio of the $$|J'|$$/$$J$$ = 0.0247(3). At lower energies, below $$T_{rm{N}}$$, a spin gap is observed in the dispersive excitations. These results are consistent with characteristics observed in weakly interacting $$S$$ = 1/2 Heisenberg chain system.

Journal Articles

Penetration of Cs and Sr into cracked dry carbonated mortar considering the contamination history of Fukushima Daiichi NPP

Yamada, Kazuo*; Tojo, Yasumasa*; Aihara, Haruka; Tomita, Sayuri*; Hokora, Hideyuki*; Shibuya, Kazutoshi*; Koma, Yoshikazu; Igarashi, Go*; Hosokawa, Yoshifumi*; Maruyama, Ippei*

Proceedings of Waste Management Symposia 2023 (WM2023) (Internet), 12 Pages, 2023/02

Journal Articles

A 3D particle-based simulation of heat and mass transfer behavior in the EAGLE ID1 in-pile test

Zhang, T.*; Morita, Koji*; Liu, X.*; Liu, W.*; Kamiyama, Kenji

Annals of Nuclear Energy, 179, p.109389_1 - 109389_10, 2022/12

 Times Cited Count:3 Percentile:34.71(Nuclear Science & Technology)

Journal Articles

Frontiers of studies utilizing accelerator mass spectrometry in geoscience

Honda, Maki

Journal of the Mass Spectrometry Society of Japan, 70(4), p.282 - 283, 2022/12

The development of measurement and chemical separation techniques in the accelerator mass spectrometry (AMS) method has enabled highly sensitive analysis of $$^{244}$$Pu (half-life 8.1$$times$$10$$^{7}$$ years), $$^{60}$$Fe (half-life 2.62$$times$$10$$^{6}$$ years), and $$^{90}$$Sr (half-life 28.9 years) in AMS. For example, the study analyzing $$^{244}$$Pu in ferromanganese crust samples successfully quantified $$^{244}$$Pu from outside the solar system, which had been hidden by $$^{244}$$Pu from nuclear tests. Furthermore, the research has revealed that $$^{244}$$Pu is produced in neutron star mergers, etc., leading to unraveling the production sites where the heavy elements originate. This topic highlights the frontline of studies on $$^{244}$$Pu, $$^{60}$$Fe, and $$^{90}$$Sr utilizing AMS.

Journal Articles

Birchite Cd$$_{2}$$Cu$$_{2}$$(PO$$_{4}$$)$$_{2}$$SO$$_{4}$$ $$cdot$$ 5H$$_{2}$$O as a model antiferromagnetic spin-1/2 Heisenberg $${it J}$$$$_{1}$$-$${it J}$$$$_{2}$$ chain

Fujihara, Masayoshi; Jeschke, H. O.*; Morita, Katsuhiro*; Kuwai, Tomohiko*; Koda, Akihiro*; Okabe, Hirotaka*; Matsuo, Akira*; Kindo, Koichi*; Mitsuda, Setsuo*

Physical Review Materials (Internet), 6(11), p.114408_1 - 114408_8, 2022/11

 Times Cited Count:2 Percentile:7.18(Materials Science, Multidisciplinary)

$${it S}$$ = 1/2 Heisenberg $${it J}$$$$_{1}$$-$${it J}$$$$_{2}$$ chain antiferromagnets have been investigated extensively due to their exotic magnetic states. Here, we report the magnetic behavior of birchite Cd$$_{2}$$Cu$$_{2}$$(PO$$_{4}$$)$$_{2}$$SO$$_{4}$$$$cdot$$5H$$_{2}$$O and its effective spin model. Experimental studies by magnetic susceptibility, magnetization, heat capacity, and $$mu$$SR measurements indicate the absence of long-range order down to 0.4 K. Theoretical studies reveal that birchite is a model compound for the $${it J}$$$$_{1}$$-$${it J}$$$$_{2}$$ antiferromagnetic chain: the intrachain interactions $${it J}$$$$_{1}$$ and $${it J}$$$$_{2}$$ are antiferromagnetic and their magnitude is about 100 times larger than the interchain interactions. The magnitude of $${it J}$$$$_{2}$$ is two to three times larger than that of $${it J}$$$$_{1}$$, thus the spin gap is expected to be only a few percent of that of $${it J}$$$$_{1}$$. The temperature dependence of the specific heat shows a broad peak at about 1 K ($$simeq$$ 0.036 $${it J}$$$$_{1}$$), which suggests the presence of a spin gap.

Journal Articles

Particle-based simulation of jet impingement behaviors

Takatsuka, Daichi*; Morita, Koji*; Liu, W.*; Zhang, T.*; Nakamura, Takeshi*; Kamiyama, Kenji

Proceedings of 12th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS12) (Internet), 10 Pages, 2022/10

Journal Articles

On the origin of localized electrons in SrTiO$$_3$$ metallized by hydrogen irradiation

Ito, Takashi

Meson, (56), p.21 - 26, 2022/09

no abstracts in English

858 (Records 1-20 displayed on this page)