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Hiraoka, Hirokazu; Kawasaki, Kohei*; Kimura, Masanori; Saito, Shota; Ezaki, Iwao*; Kameda, Shuji*; Togawa, Orihiko
Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 25(3), p.111 - 121, 2026/08
A method to enable the simultaneous inspection of tires and the wiper area using a portable radiation portal monitor is being developed to improve the efficiency of vehicle inspection during contamination screening. To achieve this, we devised an approach to identify whether contamination is located on the tires or in the wiper area. We designed an L-shaped measurement configuration, where detectors are positioned horizontally near the ground and vertically upright. An identification approach based on this L-shaped configuration was evaluated using Monte Carlo simulations. The results showed that the magnitude relation of counts measured by the horizontal and vertical detectors varies depending on whether the point source is located on the tires or in the wiper area. We examined an identification method that utilizes this relationship to determine the contaminated location. Next, we conducted measurements using a portal monitor (Gamma Pole, manufactured by Chiyoda Technol) and attempted to identify the contaminated location by the L-shaped measurement method. As a result, in the experiment simulating tire contamination, all 30 measurements correctly identified the tires as the contaminated location. In contrast, in the experiment simulating wiper contamination, 29 out of 30 measurements correctly identified the wiper area.
Saito, Shota; Kimura, Masanori; Hiraoka, Hirokazu
Kotsu Kogaku Kenkyu Happyokai Koenshu, 45, p.844 - 849, 2025/00
no abstracts in English
Aoyagi, Noboru; Motokawa, Ryuhei; Okumura, Masahiko; Ueda, Yuki; Saito, Takumi*; Nishitsuji, Shotaro*; Taguchi, Tomitsugu*; Yomogida, Takumi; Sazaki, Gen*; Ikeda, Atsushi
Communications Chemistry (Internet), 7, p.128_1 - 128_13, 2024/06
Times Cited Count：3 Percentile：23.67(Chemistry, Multidisciplinary)Togawa, Orihiko; Hokama, Tomonori; Hiraoka, Hirokazu; Saito, Shota
JAEA-Research 2023-011, 78 Pages, 2024/03
JAEA-Research-2023-011.pdf:2.09MB
When radionuclides are released into the atmospheric environment at a nuclear emergency, protective measures such as evacuation and temporal relocation are carried out using motor vehicles such as private cars and buses to reduce radiation exposure to residents. To confirm conditions of contamination for the evacuated/relocated residents and the used motor vehicles, contamination inspection is conducted in the middle of the route from border areas of Nuclear Emergency Planning Zone to evacuation shelters. In the present inspection in Japan, a value of OIL4 = 40,000 cpm is used as decontamination criteria. For the details and derivation methods of the value, however, no official documents are found which give systematically detailed descriptions and explanation. It is also recognized that even few experts on nuclear emergencies can explain these subjects in detail as a whole. In order to explain scientifically and technically the OIL4 value of decontamination criteria used in contamination inspection in Japan, this report aims at investigating and estimating the deviation methods of OIL4, and examining and considering these results. To achieve the objectives, we show the bases for decontamination criteria, and investigate and estimate the derivation methods for limits of a surface contamination density corresponding to the generic criteria for each exposure pathway. Moreover, we give the OIL4 value some consideration and suggestions from a viewpoint of positioning and feature of OIL4 in Japan, and cautionary points at revising the value.
V
Al alloysSoda, Kazuo*; Harada, Shota*; Hayashi, Toshimitsu*; Kato, Masahiko*; Ishikawa, Fumihiro*; Yamada, Yu*; Fujimori, Shinichi; Saito, Yuji
Materials Transactions, 57(7), p.1040 - 1044, 2016/06
Times Cited Count：3 Percentile：14.45(Materials Science, Multidisciplinary)
-(BEDT-TTF)
ICl under high pressureTakaku, Masaki; Higemoto, Wataru; Sato, Kazuhiko*; Saito, Shota*; Ito, Takashi; Fujihara, Masayoshi
no journal, ,
no abstracts in English
Kawasaki, Kohei*; Hiraoka, Hirokazu; Ezaki, Iwao*; Kameda, Shuji*; Kimura, Masanori; Saito, Shota
no journal, ,
In the current contamination screening plan, the vehicle's tires are measured using a portable radiation portal monitor, while wiper area is measured by an inspector using a survey meter. These two measurements confirm that contamination levels are below the screening thresholds. However, if both areas could be screened simultaneously using the portal monitor, it would improve the efficiency of the screening process. In this study, the degree of efficiency that can be expected from simultaneous screening by the portal monitor was verified through simulated screening using actual vehicles. The results showed that this screening method can contribute to a 9.4 second time reduction, from an average of 29.5 seconds to 20.1 seconds per vehicle, and a reduction of two inspectors per lane.
Hiraoka, Hirokazu; Kawasaki, Kohei*; Kimura, Masanori; Saito, Shota; Ezaki, Iwao*; Kameda, Shuji*
no journal, ,
In the current contamination screening plan, the vehicle's tires are measured using a portable radiation portal monitor, while wiper area is measured by an inspector using a survey meter. These two measurements confirm that contamination levels are below the screening thresholds. However, if both areas could simultaneously be screened using the portal monitor, it would improve the efficiency of the screening process. In this study, we estimated the accuracy of simultaneous screening using the portal monitor based on radiation counts obtained from examinations using a vehicle. As a result, it was shown that tire screening with the portal monitor is less affected by wiper area's contamination and achieves high accuracy. Furthermore, it was found that keeping the alarm threshold low in wiper area screening can reduce the likelihood of false negatives. However, since wiper area screening has a higher likelihood of false positives, it is recommended that an inspector re-measure wiper area only if an alarm is triggered.
Onuki, Toshihiko; Masaki, Shota*; Utsunomiya, Satoshi*; Tanaka, Kazuya*; Yu, Q.; Kozai, Naofumi; Sakamoto, Fuminori; Saito, Takumi
no journal, ,
Some low-molecular-mass organic species released from the yeast after exposure to CeNPs. Although the CeNPs did not cause cytotoxicity, the organic species enhaced solubility of Ce nano particles. Formation of Ce nano-particles on the cell surface suppressed the oxidation of trivalent Ce to tetravalent Ce by Mn oxides.
Hiraoka, Hirokazu; Kawasaki, Kohei*; Kimura, Masanori; Togawa, Orihiko; Saito, Shota; Ezaki, Iwao*
no journal, ,
When the nuclear emergency occurs, inhabitants take the contamination inspection to evacuate. A large number of vehicle will come to the inspection area and make there congested. To do the quick inspection, simultaneous measurement of tires and wipers using the portable radiation portal monitors for vehicles is a key point. Consequently, we attempted the count rates obtained from tires and wipers are discriminated. First, the vehicle was driven at 5 km/h and the 
-ray counts rate was measured by the monitor. 
Ba sources were attached around the tire or on the wiper and measurements were taken 30 times each. Next, discrimination conditions based on a linear function were applied to the normalized count rates, with the maximum count rate of the measured values (Net value) set to 1.0, to evaluate the discrimination accuracy between the tire and the wiper. The evaluation results showed that the pattern with the source attached around the tire correctly discriminated 29 out of 30 times, while the pattern with the source attached on the wiper correctly discriminated 20 out of 30 times. It was found that in order to improve the accuracy of discrimination, the measurement method must be improved so that there is a large difference between measured values of the tire and the wiper.
Saito, Shota; Hiraoka, Hirokazu; Kimura, Masanori
no journal, ,
In nuclear emergency, evacuees are scheduled to undergo contamination screening of their vehicles and other items along the evacuation route. To facilitate their evacuation, efficiently vehicles screening is necessary. The vehicle screening involves two types of inspections: a designated spot inspection, which all vehicles must undergo, and a detailed inspection, conducted if contamination is suspected. These inspections are conducted in separate lanes. The authors examine the lane allocation of these inspections with limited personnel and equipment. In this presentation, we present results of evaluating the efficiency of vehicle screening with different lane configurations by traffic simulator SUMO (Simulation of Urban Mobility), based on the proportion of contaminated vehicles, entry-to-exit time, and number of vehicles passing through the site.
-(BEDSe-TTF)GaCl
observed by muon spin rotation methodSaito, Shota; Higemoto, Wataru; Ito, Takashi; Fujihara, Masayoshi
no journal, ,
no abstracts in English
alloy under high pressure and high temperatureSaito, Hiroyuki; Morimoto, Shota*
no journal, ,
no abstracts in English
Kawasaki, Kohei*; Hiraoka, Hirokazu; Ezaki, Iwao*; Kimura, Masanori; Togawa, Orihiko; Saito, Shota
no journal, ,
Vehicles carrying evacuees during a nuclear emergency are subject to contamination inspections, and the operation of screening by measuring tires and wiper are required. The introduction of portable radiation portal monitors for vehicles is expected to be quick tire inspections, however, it is difficult to inspect the tire and the wiper at the same time, so further speeding up the inspection process is an issue. In this study, we attempted to discriminate each type of contamination by using a different the new set up of detectors for the purpose of simultaneous inspection of tires and wiper. We will report the usefulness of the new set up and the results of simulation calculations of detector response under realistic contamination assumptions.
Hiraoka, Hirokazu; Kawasaki, Kohei*; Kimura, Masanori; Togawa, Orihiko; Saito, Shota; Ezaki, Iwao*
no journal, ,
In nuclear emergency, vehicles which evacuating inhabitants use be taken the contamination inspection. For the quick inspection, it seems that realization of simultaneous inspection of tires and wipers by portable radiation portal monitors for vehicles is necessary. In order to fulfill the simultaneous inspection, the authors develop the measuring method which is able to suitably distinguish and evaluate each contamination. Monte Carlo simulation showed ahead that the new set-up of detectors improves the discriminative ability for contamination. In this study, based on the simulation results, the authors attached radiation sources to a vehicle, and verified the ability by the new-setup. As a result, the ability improved compared to one of the usual method.
