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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.
Takasaki, Koji; Sagawa, Naoki; Kurosawa, Shigeyuki; Mizuniwa, Harumi
Journal of Nuclear Science and Technology, 48(6), p.911 - 918, 2011/06
Times Cited Count：14 Percentile：69.17(Nuclear Science & Technology)An autoradiographical method using an imaging plate (IP) was developed to analyze the plutonium contamination in the plutonium handling facility and was applied to the monitoring of the workplace in a practical uranium-plutonium mixed oxide (MOX) fuel fabrication facility. A good relationship between the photo stimulated luminescence (PSL) intensities of IP and radioactivities measured by a radiation counter was obtained by the least-square fitting, taking the fading effect into consideration. The 
-radioactivities of plutonium contamination were derived from the PSL image in this IP method, and their relative errors were evaluated from exposure time.
Sagawa, Naoki; Yamazaki, Takumi; Kurosawa, Shigeyuki*; Izaki, Kenji; Mizuniwa, Harumi; Takasaki, Koji
JAEA-Technology 2010-051, 35 Pages, 2011/03
JAEA-Technology-2010-051.pdf:1.83MB
The image analysis method using a imaging plate (IP) is recent technique, and this method can get the information of radioactivity distribution by the unit of Photo Simulated Luminescence (PSL). We have investigated the PSL images obtained by measuring some plutonium samples which are radiation protection samples in order to apply imaging plate to the radiation protection at the MOX fuel facility. Plutonium spots were extracted from the PSL image extracted by the threshold, in which about 99% of the back ground was excluded, and identified by the additional requirement that the spot size is more than 40 pixels. The average background is subtracted from PSL strength of the spot area identified as Pu, and the radioactivity of the Pu spot was evaluated by multiplying the conversion calculation that is in consideration of fading.
Horikoshi, Yoshinori; Nemoto, Norio; Kurosawa, Shigeyuki*; Takasaki, Koji; Mizuniwa, Harumi
JAEA-Testing 2008-003, 29 Pages, 2008/04
JAEA-Testing-2008-003.pdf:1.65MB
In the Plutonium Fuel Technical Development Center, protective clothing suitable for sweltering radiation work was examined. Since it worried about the influence of wet protective clothing with sweat on detection of MOX powder contamination, Detection situations, the diffusion of contamination, and the osmosis and penetrability to wet protective clothing were examined about the present fabric and other new fabrics. As a result of examination, it was confirmed that the influence of detection on alpha ray in the wet condition of new fabrics was smaller than the current fabric. This report compiled the result of examination and points in the fabric selection suitable for protective clothing.
Takasaki, Koji; Sagawa, Naoki; Kurosawa, Shigeyuki*; Shioya, Satoshi; Suzuki, Kazunori; Horikoshi, Yoshinori; Mizuniwa, Harumi
JAEA-Technology 2008-028, 73 Pages, 2008/03
JAEA-Technology-2008-028.pdf:5.88MB
Recently, an imaging plate (IP) was developed. Pu analysis by an IP was studied in the JAEA Cooperative Research Scheme on the Nuclear Fuel Cycle, and the availability about detection of Pu and discrimination with radon progenies was shown. In order to apply these results to the radiation control, this research aims at evaluation of radioactivity, discrimination with radon progenies, and evaluation of AMAD by an IP. In the conventional autoradiography (ARG) by a ZnS and Polaroid film, Contamination of Pu can only be grasped by viewing. Since the digital data of the radiation and location is obtained by an IP, Pu can be detected quantitatively and radioactivity can be evaluated. As a result of this research, the image of alpha emitter on an IP is the same as that of the conventional ARG, and can be applied also to the ARG of beta and 
emitter. In measurement of Pu, the function of Image J (image-analysis software) was very available. Pu radioactivity was evaluated by an IP.
Sagawa, Naoki; Kurosawa, Shigeyuki*; Takasaki, Koji; Mizuniwa, Harumi
no journal, ,
no abstracts in English
Mizuniwa, Harumi; Takasaki, Koji; Horikoshi, Yoshinori; Suzuki, Kazunori; Shioya, Satoshi; Sagawa, Naoki; Kurosawa, Shigeyuki*
no journal, ,
no abstracts in English
