The Maintenance management of electricity and machinery unit on advanced volume reduction facilities

Yokota, Akira; Seya, Manato; Sugawara, Satoshi; Ishikawa, Joji; Yokobori, Tomohiko

JAEA-Technology 2026-010, 73 Pages, 2026/07

JAEA-Technology-2026-010.pdf:17.11MB

The Advanced Volume Reduction Facilities (AVRF) were constructed to produce waste packages compatible with future near-surface disposal. The facilities primarily target low-level beta/gamma solid waste generated from the Nuclear Science Research Institute and other research facilities. The processing operations at the AVRF include dismantling, sorting, repackaging, supercompaction, melting and other treatments. Since operations commenced in 1999, approximately 10,000 units (equivalent to 200-liter drums) of waste have been processed as of the end of FY2018. The conduct of treatment operations and the stable operation of AVRF require proper maintenance and management of the Electricity and Machinery Unit, which include power distribution unit, air compressor unit, exhaust unit, gas supply units, drainage units, and other electromechanical units. Since these units were first put into operation, they have been appropriately maintained and operated, including routine inspections and repairs. Compiling the operational and maintenance records of the Electricity and Machinery Unit to date is considered important for ongoing operations. This paper reports on the operational and maintenance status of the Electricity and Machinery Unit.

Compliance measures at the Radioactive Waste Treatment Facilities at the Nuclear Science Research Institute; Aseismic reinforcement of the Radioactive Waste Treatment Facility No. 3, Waste Size Reduction and Storage Facility, and Waste Volume Reduction Facility

Iketani, Shotaro; Suzuki, Takeshi; Yokobori, Tomohiko; Sugawara, Satoshi; Yokota, Akira; Kikuchi, Genta; Muraguchi, Yoshinori; Kitahara, Masaru; Seya, Manato; Kurosawa, Tsuyoshi; et al.

JAEA-Technology 2025-001, 169 Pages, 2025/08

JAEA-Technology-2025-001.pdf:14.22MB

The radioactive waste treatment facilities at the Nuclear Science Research Institute includes the Radioactive Waste Treatment Facility No. 3, Waste Size Reduction and Storage Facility, and Waste Volume Reduction Facility. These three facilities come under the purview of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors, and are included under Class C of the act based on the seismic requirements specified in the Act. We assessed the seismic capacity of these three radioactive waste treatment facilities based on the current Building Standards Act, to verify whether they comply with the new regulatory requirements enforced by the Nuclear Regulation Authority (NRA) in the aftermath of the 2011 nuclear accident at the Fukushima Daiichi Nuclear Power Station operated by the Tokyo Electric Power Company. We found that the allowable stress of a few structural members used in the construction of the facilities did not meet the regulatory requirements. After studying the approval granted by the NRA for the construction plans, including the design and construction methods (design and construction plans) of the three facilities on March 5, 2021, we made aseismic reinforcement at these facilities between 2021 and 2022. This report presents an overview of the seismic design of these facilities and an outline of the aseismic reinforcement conducted, management system existing, safety measures adopted, and the preoperational inspections conducted at these facilities.

Molecular dynamics simulation of high-energy beam irradiation of SiO single crystal with three different morphologies; No free surface, with a free surface, and thin films

Otsuka, Shunya*; Kimata, Satoshi*; Sasajima, Yasushi*; Ishikawa, Norito

ECS Journal of Solid State Science and Technology, 13(11), p.114005_1 - 114005_10, 2024/11

https://doi.org/10.1149/2162-8777/ad905a

High-energy beam irradiation of SiO crystal was simulated by the molecular dynamics method. Three types of specimen structures were examined: a single crystal without a free surface, a single crystal with a free surface, and a thin film. The single crystal structure of quartz without the free surface gradually became amorphous with increasing thermal energy. In case of single crystal structure with the free surface, high thermal energy deposition resulted in a facet-like structure at the impacted surface, which corresponds to the V-shaped nanostructure which has been observed by the previous experiment. Nano-hole formation was observed in the irradiation process of the film structure.

Tuning critical current density properties of YBaCuOy thin films under longitudinal magnetic field by using heavy-ion irradiation

Sueyoshi, Tetsuro*; Enokihata, Ryusei*; Yamaguchi, Hiroshi*; Semboshi, Satoshi*; Ozaki, Toshinori*; Sakane, Hitoshi*; Nishizaki, Terukazu*; Ishikawa, Norito

Superconductor Science and Technology, 37(7), p.075010_1 - 075010_7, 2024/06

https://doi.org/10.1088/1361-6668/ad51ae

We attempted to improve the critical current density (Jc) under a longitudinal magnetic field (LMF) by using columnar defects (CDs) tilted toward the transport current, where the CDs were produced with 80 MeV Xe ions at an incident angle(s) up to 87.5 degree relative to the c-axis of YBaCuOy thin films. The formation of CDs extending throughout the film was confirmed by cross-sectional transmission electron microscopy. The CDs tilted at 87.5 degree weakened the magnetic field dependence of Jc under the LMF, providing a Jc higher than that of the unirradiated film in a high magnetic field. This is the first study to demonstrate that CDs and/or irradiation defects contribute to flux pinning under the LMF in high-Tc superconductors.

Radiation exposure and oxidative stress status of wild Japanese macaques in the ex-evacuation zone of the Fukushima Daiichi Nuclear Power Plant accident

Ishikawa, Ryoya*; Suzuki, Masatoshi*; Kino, Yasushi*; Endo, Satoru*; Nakajima, Hiroo*; Oka, Toshitaka; Takahashi, Atsushi*; Shimizu, Yoshinaka*; Suzuki, Toshihiko*; Shinoda, Hisashi*; et al.

KEK Proceedings 2022-2, p.61 - 66, 2022/11

https://lib-extopc.kek.jp/preprints/PDF/2022/2225/2225002.pdf

The balance between oxidative stress and antioxidant activity, which is a defense mechanism against oxidative stress, was investigated in the liver and bladder of wild Japanese macaques captured in Fukushima Prefecture. No significant induction of oxidative stress by exposure to environmental radionuclides after the Fukushima nuclear accident was observed, suggesting that the stress defense mechanism of the organism is activated in some organs.

scattering length from photoproduction on the proton near the reaction threshold

Ishikawa, Takatsugu*; Fujimura, Hisako*; Fukasawa, Hiroshi*; Hashimoto, Ryo*; He, Q.*; Honda, Yuki*; Hosaka, Atsushi; Iwata, Takahiro*; Kaida, Shun*; Kasagi, Jirota*; et al.

Physical Review C, 101(5), p.052201_1 - 052201_6, 2020/05

https://doi.org/10.1103/PhysRevC.101.052201

Zeolitic vanadomolybdates as high-performance cathode-active materials for sodium-ion batteries

Zhang, Z,*; Wang, H.*; Yoshikawa, Hirofumi*; Matsumura, Daiju; Hatao, Shuya*; Ishikawa, Satoshi*; Ueda, Wataru*

ACS Applied Materials & Interfaces, 12(5), p.6056 - 6063, 2020/02

https://doi.org/10.1021/acsami.9b19808

Guidance for gamma spectrometry intercomparison based on the information obtained through five intercomparisons during the Fukushima mapping project

Mikami, Satoshi; Ishikawa, Daisuke*; Matsuda, Hideo*; Hoshide, Yoshifumi*; Okuda, Naotoshi*; Sakamoto, Ryuichi*; Saito, Kimiaki

Journal of Environmental Radioactivity, 210, p.105938_1 - 105938_7, 2019/12

https://doi.org/10.1016/j.jenvrad.2019.03.014

Five intercomparisons of in situ spectrometry by 6-7 participating teams have been conducted between December 2011 and August 2015 at sites in Fukushima prefecture which affected by the fallout of FDNPS accident occurred in March 2011. The evaluated deposition densities agreed within 5-6% in terms of coefficient of variation (CV) for radiocesium (Cs and Cs), by our best achievement, and the ratio of Cs/Cs in deposition density agreed within 1-2% in CV, through five intercomparisons. These results guarantee the accuracy of the measurements of the mapping project. Two different methods for intercomparison were conducted: (1) sequential measurements at an identical point; and (2) simultaneous measurements in a narrow area within 3 m radius. In a comparison between the two methods at a site, no significant difference was observed between the results. The standard protocols for the two different intercomparison methods were proposed based on our experience.

Oxidation characteristics of lead-alloy coolants in air ingress accident

Kondo, Masatoshi*; Okubo, Nariaki; Irisawa, Eriko; Komatsu, Atsushi; Ishikawa, Norito; Tanaka, Teruya*

Energy Procedia, 131, p.386 - 394, 2017/12

https://doi.org/10.1016/j.egypro.2017.09.473

The chemical behaviors of lead (Pb) based coolants in the air ingress accident of fast reactors were investigated by means of the thermodynamic considerations and the static oxidation experiments for Pb alloys at various chemical compositions. The results of the static oxidation tests for lead-bismuth (Pb-Bi) alloys indicated that Pb was depleted from the alloy due to the preferential formation of PbO in air at 773K. Pb-Bi oxide and BiO were formed after the enrichment of Bi in the alloys due to the Pb depletion. The oxidation rates of the alloys were much larger than that of the steels, and became larger with higher Pb concentration in the alloys. The compatibility of Pb-Bi alloys with stainless steel was worse when the Pb concentration in the alloys became low, since the dissolution type corrosion was promoted by the Bi composition in the alloy. The Pb-Li alloys were oxidized as they formed LiPbO and LiCO. Then, Li was depleted from the alloy.

The CIELO collaboration; Progress in international evaluations of neutron reactions on Oxygen, Iron, Uranium and Plutonium

Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Kahler, A. C.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Pigni, M.*; Dunn, M.*; Leal, L.*; et al.

EPJ Web of Conferences, 146, p.02001_1 - 02001_9, 2017/09

https://doi.org/10.1051/epjconf/201714602001

The CIELO collaboration has studied neutron cross sections on nuclides (O, Fe, U and Pu) that significantly impact criticality in nuclear technologies with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.