An investigation of abnormal personal doses of external exposure

Objective A case of abnormal personal doses of external exposure was reported in this paper. According to the investigation of the dose rates of the radiation sources and the workplace, the actualdose was estimated correctly. Methods The radiation level of storage containers at work site was measured by BH3103A portable X and γ radiation dosimeter. The thermoluminescence personal dosimeter was placed in the work site for a month, then it was measured with the RGD3 dosimeter to estimate the dose rateat the work site. The actual personal dose of external exposure was calculated based on the dose rateand the effective working time of the staff in the field. Results The location with highest dose rate was the empty containers which had been filled with raw materials. The second was a container filled with ingredients. The dose rate on the surface of empty container is generally higher than that of full container. The time weighted method was used to calculate the possible dose which was 2.32 mSv for this position. Conclusion The personal dose measured by the personal dosimeter was found to be erroneous, and it should be recorded with the revised dose of 2.32 mSv. 摘要： 目的 通过对某单位出现外照射个人剂量监测结果异常的岗位的现场剂量水平以及辐射来源进行调查, 调查 工作人员实际所受到的外照射个人剂量。 方法 用 BH3103A 便携式 X、γ 辐射剂量率测量仪对工作现场存放容器表 面剂量率进行测量, 调查辐射来源；在外照射个人剂量异常岗位工作现场放置热释光个人剂量计一个月后, 用 RGD3 型热释光剂量仪对剂量计进行测量, 并结合工作人员在现场的有效工作时间, 推算该岗位工作人员实际所受外 照射个人剂量。 结果 辐射水平最高的是装过原料的空容器, 其次是装满原料的容器；空容器表面剂量率普遍大于满 容器;用时间加权的方法计算出该岗位人员可能接受的剂量水平为 2.32 mSv。 结论 本次出现工作人员异常的个人 剂量计的监测结果不是本人真实的受照剂量, 应当剔除, 以估算的名义剂量 2.32 mSv 代替其本季度的受照剂量。