Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2015, Vol. 26 ›› Issue (6): 060103 doi: 10.13538/j.1001-8042/nst.26.060103

• SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS • Previous Articles     Next Articles

Decommissioning analysis of the scrapers in the NSRL Linac using depth profiling

HE Li-Juan, LI Yu-Xiong, LI Wei-Min, CHEN Yu-Kai, REN Guang-Yi   

  1. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
  • Contact: LI Yu-Xiong E-mail:lyx@ustc.edu.cn
  • Supported by:
    Supported by National Natural Science Foundation of China (Nos. 11175180 and 11175182)
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HE Li-Juan, LI Yu-Xiong, LI Wei-Min, CHEN Yu-Kai, REN Guang-Yi. Decommissioning analysis of the scrapers in the NSRL Linac using depth profiling.Nuclear Science and Techniques, 2015, 26(6): 060103     doi: 10.13538/j.1001-8042/nst.26.060103

Abstract:

For a high-energy electron facility, estimates of induced radioactivity in materials are of considerable importance to ensure that the exposure of personnel and the environment remains as low as reasonably achievable. In addition, accurate predictions of induced radioactivity are essential to the design, operation, and decommissioning of a high-energy electron linear accelerator. In the case of the 200-MeV electron linac of the National Synchrotron Radiation Laboratory (NSRL), the electrons are accelerated by five acceleration tubes and collimated by copper scrapers. The scrapers, which play a vital role in protecting the acceleration cavity, are bombarded by many electrons over a long-term operation, which causes a significant amount of induced radioactivity. Recently, the NSRL Linac is the first high-energy electron linear accelerator in China to be out of commission. Its decommissioning is highly significant for obtaining decommissioning experience. This paper focuses on the measurement of induced radioactivity on the fourth scraper, where the electron energy was 158 MeV. The radionuclides were classified according to their half-lives. Such a classification provides a reliable basis for the formulation of radiation protection and facility decommissioning. To determine the high-radioactivity area and to facilitate the decommissioning process, the slicing method was applied in this study. The specific activity of 60Co in each slice was measured at a cooling time of ten months, and the results were compared with the predictions generated by Monte Carlo program FLUKA. The trend of the measured results is in good agreement with the normalized simulation results. The slicing simulation using Monte Carlo method is useful for the determination of high-radiation areas and proper material handling protocols and, therefore, lays a foundation for the accumulation of decommissioning experience.

Key words: NSRL Linac, Decommissioning, Scraper, 60Co, Slicing method