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目的了解三门核电站运行前宁海毗邻区域环境γ辐射剂量和环境介质的放射性水平,建立环境辐射本底基线数据。方法采用碘化钠闪烁体探测法和热释光累积剂量法测定监测区域环境γ外照射剂量率和环境辐射累积剂量,采用低本底α/β探测装置测定监测区域水源水总α和总β辐射剂量,食品样品放射性核素采用γ能谱仪测定。结果监测区域居民人均年有效剂量为0.928 mSv;原野γ外照射剂量率为(98.32±21.08)nGy/h;环境辐射年累积剂量为(1.040±0.044)mSv。原野γ外照射剂量率和环境辐射累积剂量均有季节性差异。20 km范围内监测区域环境γ外照射剂量率和环境辐射累积剂量与10 km和30 km范围的测量结果差异无统计学意义。食品样品放射性核素检出值均远小于国家标准,水源水样品总放射性指标符合国家饮用水标准。结论三门核电站宁海毗邻区域放射性本底在正常水平范围内,环境放射性本底有季节性差异。本次调查为三门核电站运行前宁海毗邻区域放射性本底建立了基线数据,~(90)Sr、~(137)Cs、~(131)I等人工放射性核素是今后食品样品监测的重点。
Objective To understand the environmental γ radiation dose and environmental media radioactivity in the adjacent area of Ninghai before the operation of Sanmen NPP, and establish the baseline data of environmental radiation background. Methods Sodium iodide scintillator detection method and pyro-luminescence cumulative dose method were used to determine the γ radiation dose and the radiation dose of the environment in the monitoring area. The total α and β Radiation dose, food samples radionuclides using gamma spectrometer. Results The annual average effective dose per inhabitant in the monitoring area was 0.928 mSv. The dose rate of field γ was (98.32 ± 21.08) nGy / h. The cumulative dose of environmental radiation was (1.040 ± 0.044) mSv. There was a seasonal difference in the dose rate of field γ external radiation and the cumulative dose of environmental radiation. Within the range of 20 km, there was no significant difference between the γ radiation dose rate and the accumulated environmental radiation dose in the monitored area and the measurements in the range of 10 km and 30 km. The radionuclide detection values of food samples are far less than the national standards, and the total radioactivity index of water samples meets the national drinking water standards. Conclusions The radioactive background of the adjacent area of Sanmen NPP in Ninghai is within the normal range, and there is a seasonal difference in the environmental radioactive background. The survey established baseline data for the radioactive background of the adjacent Ninghai district before the operation of Sanmen NPP. The artificial radionuclides such as ~ (90) Sr, ~ (137) Cs and ~ (131) I are the key points for the future monitoring of food samples.