Optimization of dissolved hydrogen concentration for mitigating corrosive conditions of pressurised water reactor primary coolant under irradiation, 2; Evaluation of electrochemical corrosion potential

Hata, Kuniki; Hanawa, Satoshi; Chimi, Yasuhiro; Uchida, Shunsuke; Lister, D. H.*

Journal of Nuclear Science and Technology, 60(8), p.867 - 880, 2023/08

https://doi.org/10.1080/00223131.2022.2127955

One of the major subjects for evaluating the corrosive conditions in the PWR primary coolant was to determine the optimal hydrogen concentration for mitigating PWSCC without any adverse effects on major structural materials. As suitable procedures for evaluating the corrosive conditions in PWR primary coolant, a couple of procedures, i.e., water radiolysis and ECP analyses, were proposed. The previous article showed the radiolysis calculation in the PWR primary coolant, which was followed by an ECP study here. The ECP analysis, a couple of a mixed potential model and an oxide layer growth model, was developed originally for BWR conditions, which was extended to PWR conditions with adding Li (Na) and H effects on the anodic polarization curves. As a result of comparison of the calculated results with INCA in-pile-loop experiment data as well as other experimental data, it was confirmed that the ECPs calculated with the coupled analyses agreed with the measured within 100mV discrepancies.

Research on atmospheric radioactivity concentration in the specified reconstruction and revitalization base (FY2018-FY2021)

Abe, Tomohisa; Funaki, Hironori; Yoshimura, Kazuya; Shiribiki, Natsu*; Sanada, Yukihisa

JAEA-Data/Code 2023-001, 38 Pages, 2023/05

JAEA-Data-Code-2023-001.pdf:3.04MB
JAEA-Data-Code-2023-001-appendix(CD-ROM).zip:32.02MB

In this study, commissioned by the Cabinet Office, we conducted a survey on radioactive materials in atmospheric dust in three municipalities (Futaba Town, Okuma Town, and Tomioka Town) in Fukushima Prefecture to contribute to the assessment of internal exposure in the Specified Reconstruction and Revitalization Base (SRRB). Air dust samplers were installed in the targeted municipalities to investigate the atmospheric Cs concentrations and to evaluate internal exposure doses based on measured value. This report summarizes the results of measurements between 2018 and 2021. A database of information on internal exposure dose assessment results based on atmospheric radioactivity concentrations and actual measurements, and meteorological observation data was compiled.

Research and development of the sample-return technique for fuel debris using the unmanned underwater vehicle (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; National Institute of Maritime, Port and Aviation Technology*

JAEA-Review 2022-070, 70 Pages, 2023/03

JAEA-Review-2022-070.pdf:5.27MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Research and development of the sample-return technique for fuel debris using the unmanned underwater vehicle" conducted in FY2021. The present study aims to develop a fuel debris sampling device that comprises a neutron detector with radiation resistance and enhanced neutron detection efficiency, an end-effector with powerful cutting and collection capabilities, and a manipulator under the Japan-UK joint research team. We will also develop a fuel debris sampling system that can be mounted on an unmanned vehicle. In addition, we will develop a positioning system to identify the system position, and a technique to project the counting information of optical cameras, sonar, and neutron detectors to be developed ...

Development of adjusted nuclear data library for fast reactor application

Yokoyama, Kenji

EPJ Web of Conferences, 281, p.00004_1 - 00004_10, 2023/03

https://doi.org/10.1051/epjconf/202328100004

In Japan, development of adjusted nuclear data library for fast rector application based on the cross-section adjustment method has been conducted since the early 1990s. The adjusted library is called the unified cross-section set. The first version was developed in 1991 and is called ADJ91. Recently, the integral experimental data were further expanded to improve the design prediction accuracy of the core loaded with minor actinoids and/or degraded Pu. Using the additional integral experimental data, development of ADJ2017 was started in 2017. In 2022, the latest unified cross-section set AJD2017R was developed based on JENDL-4.0 by using 619 integral experimental data. An overview of the latest version with a review of previous ones will be shown. On the other hand, JENDL-5 was released in 2021. In the development of JENDL-5, some of the integral experimental data used in ADJ2017R were explicitly utilized in the nuclear data evaluation. However, this is not reflected in the covariance data. This situation needs to be considered when developing a unified cross-section set based on JENDL-5. Preliminary adjustment calculation based on JENDL-5 is performed using C/E (calculation/experiment) values simply evaluated by a sensitivity analysis. The preliminary results will be also discussed.

Ferromagnetic crossover within the ferromagnetic order of UTe

Opletal, P.; Sakai, Hironori; Haga, Yoshinori; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Kambe, Shinsaku; Tokunaga, Yo

Journal of the Physical Society of Japan, 92(3), p.034704_1 - 034704_5, 2023/03

https://doi.org/10.7566/JPSJ.92.034704

We investigate the physical properties of a single crystal of uranium telluride UTe. We have confirmed that UTe crystallizes in the hexagonal structure with three nonequivalent crystallographic uranium sites. The paramagnetic moments are estimated to be approximately 1 per the uranium site, assuming a uniform moment on all the sites. A ferromagnetic phase transition occurs at = 48 K, where the in-plane magnetization increases sharply, whereas the out of-plane component does not increase significantly. With decreasing temperature further below under field-cooling conditions, the out-of-plane component increases rapidly around T= 26 K. In contrast, the in-plane component hardly changes at T. Specific heat measurement indicates no -type anomaly around T, so this is a cross-over suggesting a reorientation of the ordering moments or successive magnetic ordering on the part of the multiple uranium sites.

Selective adsorption of Pd(II) over Ag(I) in nitric acid solutions using nitrogen-donor-type adsorbents

Suzuki, Tomoya*; Otsubo, Ukyo*; Ogata, Takeshi*; Shiwaku, Hideaki; Kobayashi, Toru; Yaita, Tsuyoshi; Matsuoka, Mitsuaki*; Murayama, Norihiro*; Narita, Hirokazu*

Separation and Purification Technology, 308, p.122943_1 - 122943_7, 2023/03

https://doi.org/10.1016/j.seppur.2022.122943

HNO leaching is used in recycling Pd metal from spent products that primarily contain Ag, and most Pd residues are separated from solutions containing Ag(I). However, a small amount of Pd(II) often remains in these Ag(I) solutions. Therefore, the separation of Pd(II) and Ag(I) in HNO solutions is essential to promote efficient Pd recycling. In this study, the separation of Pd(II) and Ag(I) in HNO solutions was investigated using four N-donor-type adsorbents functionalized with amine (R-Amine), iminodiacetic acid (R-IDA), pyridine (R-Py), or bis-picolylamine (R-BPA). R-Amine, R-IDA, and R-Py selectively adsorbed Pd(II) over Ag(I), Cu(II), Ni(II), and Fe(III) from HNO solutions (0.3-7 M), but R-Amine exhibited a lower Pd adsorption efficiency. In contrast, 90% of Pd(II), Ag(I), and Cu(II) were adsorbed by R-BPA over the entire range of HNO concentrations. Structural analyses of the adsorbed metal ions using Fourier transform infrared spectroscopy and extended X-ray absorption fine structure spectroscopy revealed the separation mechanisms of the N-donor-type adsorbents. Pd(II) adsorption on R-IDA, R-Py, and R-BPA occurred via Pd(II) coordination of the functional groups (iminodiacetic acid, pyridine, and bis-picolylamine, respectively), whereas that on R-Amine occurred via anion exchange of NO with [Pd(NO)]. The coordinative adsorption mechanisms resulted in the higher Pd(II) adsorption behaviors of R-IDA, R-Py, and R-BPA. HCl (5.0 M) and thiourea (0.1 M) eluents desorbed 83% of Pd(II) from R-IDA and 95% from R-Py, respectively. R-Py was the most effective Pd(II) adsorbent based on adsorption selectivity and desorption efficiency.

Conformation, hydration, and ligand exchange process of ruthenium nitrosyl complexes in aqueous solution; Free-energy calculations by a combination of molecular-orbital theories and different solvent models

Kido, Kentaro; Kaneko, Masashi

Journal of Computational Chemistry, 44(4), p.546 - 558, 2023/02

AA2022-0469.pdf:1.33MB

https://doi.org/10.1002/jcc.27021

Development of genetic and electrochemical diagnosis and inhibition technologies for invisible corrosion caused by microorganisms (Contract Research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; National Institute for Materials Science*

JAEA-Review 2022-045, 82 Pages, 2023/01

JAEA-Review-2022-045.pdf:4.6MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Development of genetic and electrochemical diagnosis and inhibition technologies for invisible corrosion caused by microorganisms" conducted in FY2021. The present study aims to develop innovative diagnostic techniques such as accelerated test specimens and on-site genetic testing for microbially induced and accelerated corrosion of metallic materials (microbially influenced corrosion, MIC), and to identify the conditions that promote MIC at 1F for proposing methods to prevent MIC through water quality and environmental control. We also aim to develop a research base based on materials, microorganisms, and electrochemistry, to develop technologies that can be used by engineers in the field, …

Introduction of Cu to the inside of the crevice by chelation and its effect on crevice corrosion of Type 316L stainless steel

Aoyama, Takahito; Kato, Chiaki

Corrosion Science, 210(2), p.110850_1 - 110850_10, 2023/01

https://doi.org/10.1016/j.corsci.2022.110850

The chelated complex of Cu: [Cu(EDTA)] was used to introduce Cu from outside to the inside of crevice. The introduced Cu was expected to act as an inhibitor for the crevice corrosion on stainless steels. Crevice corrosion tests, confirmed the introduction of Cu to the inside of the crevice via electromigration of [Cu(EDTA)] was confirmed. Migrated [Cu(EDTA)] reacted with H and inhibited decrease in pH inside the crevice, where Cu was separated from [Cu(EDTA)] and suppressed active dissolution of the stainless steel.

Measurements of capture cross-section of Nb by activation method and half-life of Nb by mass analysis

Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi

Journal of Nuclear Science and Technology, 11 Pages, 2023/00

https://doi.org/10.1080/00223131.2023.2198526

The thermal-neutron capture cross section () and resonance integral (I) for Nb among nuclides for decommissioning were measured by an activation method and the half-life of Nb by mass analysis. Niobium-93 samples were irradiated with a hydraulic conveyer installed in the research reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Gold-aluminum, cobalt-aluminum alloy wires were used to monitor thermal-neutron fluxes and epi-thermal Westcott's indexes at an irradiation position. A 25-m-thick gadolinium foil was used to sort out reactions ascribe to thermal-and epi-thermal neutrons. Its thickness provided a cut-off energy of 0.133 eV. In order to attenuate radioactivity of Ta due to impurities, the Nb samples were cooled for nearly 2 years. The induced radio activity in the monitors and Nb samples were measured by -ray spectroscopy. In analysis based on Westcott's convention, the and I values were derived as 1.110.04 barn and 10.50.6 barn, respectively. After the -ray measurements, mass analysis was applied to the Nb sample to obtain the reaction rate. By combining data obtained by both -ray spectroscopy and mass analysis, the half-life of Nb was derived as (2.000.15)10 years.