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.

Verification of probabilistic fracture mechanics analysis code for reactor pressure vessel

Li, Y.; Katsumata, Genshichiro*; Masaki, Koichi; Hayashi, Shotaro*; Itabashi, Yu*; Nagai, Masaki*; Suzuki, Masahide*; Kanto, Yasuhiro*

Journal of Pressure Vessel Technology, 143(4), p.041501_1 - 041501_8, 2021/08

https://doi.org/10.1115/1.4049693

Activities of Working Group on Verification of PASCAL; Fiscal year 2015

Li, Y.; Hayashi, Shotaro*; Itabashi, Yu*; Nagai, Masaki*; Kanto, Yasuhiro*; Suzuki, Masahide*; Masaki, Koichi*

JAEA-Review 2017-005, 80 Pages, 2017/03

JAEA-Review-2017-005.pdf:16.85MB

For the improvement of the structural integrity assessment methodology on reactor pressure vessels (RPVs), the probabilistic fracture mechanics (PFM) analysis code PASCAL has been developed and improved in JAEA based on latest knowledge. The PASCAL code evaluates the failure probabilities and frequencies of Japanese RPVs under transient events such as pressurized thermal shock considering neutron irradiation embrittlement. In order to confirm the reliability of the PASCAL as a domestic standard code and to promote the application of PFM on the domestic structural integrity assessments of RPVs, it is important to verify the probabilistic variables, functions and models incorporated in the PASCAL and summarize the verification processes and results as a document. On the basis of these backgrounds, we established a working group, composed of experts on this field besides the developers, on the verification of the PASCAL3 which is a PFM analysis module of PASCAL, and the source program of PASCAL3 was released to the members of working group. Through one year activities, the applicability of PASCAL in structural integrity assessments of domestic RPVs was confirmed with great confidence. This report summarizes the activities of the working group on the verification of PASCAL in FY2015.

Contribution of particulate Cs from rivers to Cs concentrations in coastal sediment off Fukushima

Suzuki, Shotaro*; Sakuma, Kazuyuki; Tsuruta, Tadahiko; Matsumoto, Akira*; Amano, Yosuke*; Enomoto, Masahiro*; Morioka, Yoshiaki*; Kamiyama, Kyoichi*; Takata, Hyoe*

no journal, , 

Mesoscopic structure of vermiculite and weathered biotite clays in suspension with and without cesium ions

Motokawa, Ryuhei; Endo, Hitoshi*; Yokoyama, Shingo*; Nishitsuji, Shotaro*; Yaita, Tsuyoshi; Kobayashi, Toru; Suzuki, Shinichi

no journal, , 

no abstracts in English