Feasibility study of the one-dimensional radiation distribution sensing method using an optical fiber sensor based on wavelength spectrum unfolding

Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*; Yamazaki, Atsushi*; Sato, Yuki; Torii, Tatsuo; Wakaida, Ikuo

Journal of Nuclear Engineering and Radiation Science, 7(4), p.042002_1 - 042002_7, 2021/10

https://doi.org/10.1115/1.4048841

For the application in the measurement of the high dose rate hot spots inside the Fukushima Daiichi Nuclear Power Station (FDNPS) buildings, we propose a novel one-dimensional radiation distribution sensing method using an optical fiber sensor based on wavelength spectrum unfolding. The proposed method estimates the incident position of radiation to the fiber by the unfolding of the wavelength spectrum output from the fiber edge using the fact that the attenuation length of light along the fiber depends on the wavelength. Because this method measures the integrated light intensity, this method can avoid the problem of counting loss and signal pile-up, which occurs in the radiation detector with pulse counting mode under high dose rate field. Through basic experiments using the ultraviolet light source and Sr/Y radioactive point source, basic properties of source position detection were confirmed.

Development of one-dimensional optical fiber type radiation distribution sensing method based on wavelength spectrum unfolding

Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*; Yamazaki, Atsushi*; Sato, Yuki; Torii, Tatsuo; Wakaida, Ikuo

Proceedings of International Youth Nuclear Congress 2020 (IYNC 2020) (Internet), 4 Pages, 2020/05

Impact of safety design enhancements on construction cost of the advanced sodium loop fast reactor in Japan

Kato, Atsushi; Mukaida, Kyoko

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 10 Pages, 2019/05

Improvement of economic competitiveness is a part of key requirement in the project. By adopting innovative technologies to reduce plant commodities, JSFR could achieve economic competitiveness compared with LWR. After the Fukushima-Dai-ichi Nuclear Power Plants accident, safety enhancement measures were added on LWR in Japan mainly against external hazards. In parallel, Safety Design Criteria and Guidelines (SDC/SDG) for SFR were constructed in the framework of Generation IV international forum. Design studies of JSFR were carried out responding to GIF SDC/SDG and lessons learn from the Fukushima accident. This reports an impact of recent safety design enhancements on JSFR construction cost. Safety design enhancement adopted in JSFR.

Benchmarking of economic evaluation models for an advanced loop-type sodium cooled fast reactor

Mukaida, Kyoko; Kato, Atsushi; Shiotani, Hiroki; Hayafune, Hiroki; Ono, Kiyoshi

Nuclear Engineering and Design, 324, p.35 - 44, 2017/12

https://doi.org/10.1016/j.nucengdes.2017.08.011

An economic calculation model based on detailed mass-flow (the JAEA model) was developed for the comprehensive evaluation of an advanced loop-type sodium-cooled fast reactor cycle system (SFR) designed in the FaCT project. The JAEA model enables calculation of the processing amount and its composition in each facility by simulating mass-flow, and has function to evaluate economics based on the processing amount. In this report, to identify the difference in evaluation methods between the JAEA model and an internationally-authorized code, and verify its calculation functions, the generation cost of SFR system was evaluated using the JAEA model and the G4-ECONS. Consequently, it was clarified that the JAEA model is influenced to higher degree by the discount rate. When the present value was not taken into account, the results of both methods were quite similar, but it was found that the sensitivity of the load factor is relatively larger the G4-ECONS than in the JAEA model.

Development of optical fiber based novel wavelength-resolved type radiation distribution sensing method

Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*; Yamazaki, Atsushi*; Sato, Yuki; Torii, Tatsuo; Wakaida, Ikuo

no journal, , 

We are developing a one-dimensional radiation distribution sensing method using optical fiber to measure the distribution of hot spots in the Fukushima Daiichi Nuclear Power Station (1F) buildings. As a new radiation distribution sensing technique applicable to high dose rate environments, a wavelength-resolved analysis method was developed. This method measures the emission wavelength spectrum derived from the interaction between the optical fiber and radiation on one side of the fiber and estimates the radiation incident position to the fiber reversely using the fact that the attenuation length of light along the fiber depends on the wavelength. In the presentation, we report the results of the principle verification of this method.

Multidimensional evaluation of FR cycle systems in the Phase-II of the feasibility study, 2; Evaluations of environmental burden reduction, proliferation resistance, technical feasibility, and business applicability

Shiotani, Hiroki; Kawasaki, Hirotsugu; Kato, Atsushi; Mukaida, Kyoko; Ono, Kiyoshi; Heta, Masanori*

no journal, , 

no abstracts in English

Development of quick and remote analysis for severe accident reactor, 8-2; Analysis of simulated U-containing debris by fiber-delivered microchip LIBS

Oba, Hironori; Akaoka, Katsuaki; Karino, Takahiro; Wakaida, Ikuo; Ouchi, Atsushi*; Miura, Yusuke*; Eto, Yoshinori*; Sakamoto, Kan*

no journal, , 

no abstracts in English

X-ray radiation simulation of a head tetrahedral phantom with intraoral metal using PHITS

Nagano, Takuya*; Matsuya, Yusuke; Kaida, Atsushi*; Nojima, Hitomi*; Furuta, Takuya; Sato, Kaoru; Yoshimura, Ryoichi*; Miura, Masahiko*

no journal, , 

A dental prosthesis such as a metal crown exists in radiation field when performing head and neck cancer radiotherapy. In our previous studies, we have evaluated the sensitizing effect ratio (SER) of the radiobiological effects around metal crowns by in vitro analysis. However, it is uncertain how much SER is actually expected in complex geometry in clinical practice. Here, we simulated the treatment plan using a head phantom with a metal crown, and evaluated the dose distributions around the metal crown in a realistic patient system by simulation. The simulation results using PHITS agree well with the SER values obtained in vitro. It has been known that localized mucositis occurs around metal crowns during radiotherapy, and this outcome is expected to provide a precise understanding of the mechanism on inflammation in tissues around metals.

Comparison between the PHITS simulation for dose enhancement around metals in the oral cavity and the biological effects

Nagano, Takuya*; Matsuya, Yusuke; Kaida, Atsushi*; Nojima, Hitomi*; Yoshimura, Ryoichi*; Miura, Masahiko*

no journal, , 

In radiotherapy, metals placed close to oral tumors are often irradiated together. To date, physical calculations and dosimetry have confirmed dose enhancement around metals; however, the biological effects remain unclear. In this study, using gold as a dental material and lead which is a high atomic number similar to gold, we investigated the biological effects of tumor cells placed close to metals after therapeutic X-rays. As a result of the cell experiment, the sensitizing effect ratios of the lead plate with 2 mm and 3 mm thicknesses at 1% survival endpoint were 1.41 and 1.27, respectively, and the ratio for the 2-mm gold plate was 1.44. Meanwhile, the PHITS simulation shows that the dose enhancement ratio with and without the metal plate was approximately 1.11, which was equivalent to the measured sensitization effect ratio. In the future, we will measure the DNA damage responses for various metal thicknesses and further elucidate the mechanism of the sensitizing effects from standpoints of a hybrid approach combined with PHITS simulation.