Radiation Protection Practices during the Helium Circulator Maintenance of the 10 MW High Temperature Gas-Cooled Reactor-Test Module (HTR-10)

Chengxiang Guo,Sheng Fang,Hong Li,Liqiang Wei,Jianzhu Cao

doi:10.1155/2016/5967831

Abstract

Current radiation protection methodology offers abundant experiences on light-water reactors, but very few studies on high temperature gas-cooled reactor (HTR). To fill this gap, a comprehensive investigation was performed to the radiation protection practices in the helium circulator maintenance of the Chinese 10 MW HTR test module (HTR-10) in this paper. The investigation reveals the unique behaviour of HTR-10’s radiation sources in the maintenance as well as its radionuclide species and presents the radiation protection methods that were tailored to these features. Owing to these practices, the radioactivity level was kept low throughout the maintenance and only low-level radioactive waste was generated. The quantitative analysis further demonstrates that the decontamination efficiency was over 89% for surface contamination and over 34% forγdose rate and the occupational exposure was much lower than both the limits of regulatory and the exposure levels in comparable literature. These results demonstrate the effectiveness of the reported radiation protection practices, which directly provides hands-on experience for the future HTR-PM reactor and adds to the completeness of the radiation protection methodology.

Highlights

Radiation protection practices protect people from harmful effects of exposure to ionizing radiation [1], which is a key issue throughout the life-cycle of a nuclear reactor
The quantitative analysis further demonstrates that the decontamination efficiency was over 89% for surface contamination and over 34% for γ dose rate and the occupational exposure was much lower than both the limits of regulatory and the exposure levels in comparable literature
The radiation protection practices and radiation data in the maintenance of high temperature gas-cooled reactor (HTR)-10’s helium circulator were investigated thoroughly in this study. This investigation reveals that the graphite dust was the most concerned radiation sources during the maintenance, in which Co-60 and Cs-137 were qualitatively identified as the primary radionuclides

Summary

Introduction

Radiation protection practices protect people from harmful effects of exposure to ionizing radiation [1], which is a key issue throughout the life-cycle of a nuclear reactor. Because the radiation sources and hazards can vary significantly between different types of reactors, the corresponding radiation protection strategies and practices have to adapt to these changes as well. Most researches on radiation protection practices of nuclear reactors are focused on the commercial light-water reactors. For those light-water nuclear reactors in operation, there has been a continuous effort to reduce the annual collective dose [2,3,4,5,6,7]. For recently developed Generation III light-water reactors, various radiation protection methods have been proposed in the design stage and the collective dose has been estimated to be lower than existing commercial light-water reactors [8, 9]

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Conclusion