| アイテムタイプ |
会議発表用資料 / Presentation(1) |
| 公開日 |
2025-09-29 |
| タイトル |
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タイトル |
Radiation Protection at a New 3 GeV Synchrotron Radiation Facility: NanoTerasu |
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言語 |
en |
| 言語 |
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|
言語 |
eng |
| 資源タイプ |
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資源タイプ識別子 |
http://purl.org/coar/resource_type/c_c94f |
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資源タイプ |
conference presentation |
| 著者 |
Hagiwara Masayuki
Matsuda Hiroki
Takeuchi Akihiro
Hayakawa Seiya
糸賀 俊朗
JASRI
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| 抄録 |
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内容記述 |
Introduction:NanoTerasu is the first synchrotron radiation facility in Japan designed to exclude most of the Experimental Hall from radiation-controlled areas by optimizing its shielding design and radiation protection systems to facilitate broader user accessibility.Objective:This paper presents the shielding design and dose control measures implemented during the commissioning phase of NanoTerasu, in preparation for user operations.Methods/Approach:he shielding was designed using semi-empirical methods supported by Monte Carlo simulations with PHITS. Structural concrete shielding encloses the 3 GeV electron linear accelerator and storage ring, with supplementary local shielding installed to suppress high-energy bremsstrahlung photons. The radiation protection system consists of access control and real-time monitoring of beam current and secondary radiation. Access is managed via personal dosimeters equipped with QR codes. Prior to beam injection, an evacuation confirmation sequence ensures that all interlocked areas are unoccupied and securely locked. Ambient dose rates are measured every 10 seconds using multiple gamma-ray and neutron detectors installed around radiation-controlled areas and at the site boundary. If the dose rate exceeds a predefined threshold, the system halts beam operation and sends an alarm to radiation safety personnel. Integrated dose throughout the facility is also monitored using several hundred passive dosimeters to ensure that the effective dose remains below 1.3 mSv over a three-month period at the boundary of radiation-controlled areas.Results/Findings:A temporary increase in ambient dose rate behind the shielding was observed near the beam injection area during initial beam commissioning. To further reduce leakage dose, additional local shielding is scheduled to be installed at beam loss points in the storage ring tunnel. Nevertheless, all measured values have remained below regulatory limits. No significant radiation exposure to users has occurred to date, and the public dose remains below the ICRP-recommended annual limit of 1 mSv.Conclusion:This design successfully minimizes radiation-controlled areas while ensuring safety and regulatory compliance. |
| 会議概要（会議名, 開催地, 会期, 主催者等） |
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内容記述 |
International Technical Safety Forum ITSF 2025 |
| 発表年月日 |
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日付 |
2025-09-23 |
