高温气冷堆核燃料元件生产线辐射危害关键控制点探讨

Radiation hazards and its key control points in nuclear fuel element production line of HTGCR

目的分析高温气冷堆(HTGCR)核燃料元件生产线生产过程中的辐射危害特点,并提出辐射危害关键控制点,为企业的辐射防护决策和管理提供技术支持。方法通过职业卫生调查确定生产线各工序辐射源项、职业人员接触情况、采取的辐射防护设施及措施,通过现场检测和个人剂量估算评估辐射防护措施的有效性,并得出辐射危害关键控制点。结果该生产线辐射源项为铀的不同化合物,职业人员接触途径为内照射和外照射,工作场所γ剂量率处于较低水平(0.11～6.26μSv/h),α表面污染(最高0.02 Bq/cm^2)、空气中铀气溶胶浓度(0.009～0.810μg/m^3)均满足控制值要求,主要岗位个人年有效剂量均低于个人剂量约束值要求,采取的辐射防护设施及措施合理有效。结论化工转化、核芯制备等工序为该生产线辐射危害关键控制点,焙烧、还原、烧结工序应合理设置局部排风装置;在生产线达到设计指标运行后,需进一步评估辐射防护措施的有效性。

Objective To study the radioactive hazards characteristics of high temperature gas cooled reactor（HTGCR）nuclear fuel element production line, find the key control points of radioactive hazards, thereby provide some technical supports for decision and management of radiation protection in this kind of enterprises. Methods The radiation source term, workers＇ occupational exposure situation, facilities and measures for radiation protection in production line were cleared by occupational health investigation; the effectiveness of radiation protection measures was evaluated through on-site testing and personal dose es-timation, thus the key control points of radiation hazards were obtained. Results The results showed that the radiative source i-tems were different kinds of uranium compounds, the occupational personnel contact ways include internal radiation and external radiation; the γ dose rate was at a low level（0. 11 ～ 6. 26 μSv/h） in workplace, meanwhile, α surface contamination（0. 02 Bq/cm^2 at most） and uranium aerosol concentration in air（0. 009 ～ 0. 810 μg/m^3） both satisfied the control value require-ments. Additionally, the individual annual effective doses in key posts were all lower than that of the constraint value, which suggested that the facilities and measures for radiation protection of production line were reasonable and effective. Conclusion The results suggested that the chemical conversion process, core preparation process, etc. were the key control points for radio-active hazards of the production line, meanwhile, the setting of local exhaust devices at roasting reduction and sintering process should be more resonable, and the effectiveness of radiation protection measures should be further evaluated after operation of the production line reached the design targets.