三门核电站宁海毗邻区域辐射水平本底调查

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,⁹⁰Sr、¹³⁷Cs、¹³¹I等人工放射性核素是今后食品样品监测的重点。

Survey of radiation baseline level in Ninghai areas adjacent to the Sanmen Nuclear Power Station

Objective To obtain the environmental gamma radiation dose and the radioactivity level of environment medium in the Ninghai areas adjacent to Sanmen Nuclear Power Station before the Station running, and to establish the baseline data for environmental background radiation.Methods The environmental gamma radiation rate and cumulative dose was measured by sodium iodide scintillation detection and cumulative dose of thermoluminescence method. The total α and total β of water source in the monitoring areas was detected by low background α or β detector, and the radionuclide in the food samples was detected by γ-ray spectrometer.Results Annual effective dose per residents in surveillance areas was 0.928 mSv. γ-ray of field external radiation dose rate was (98.32±21.08) nGy/h, and the annual cumulative environmental radiation dose was (1.040±0.044) mSv. There were seasonal differences in the γ-ray of field external radiation dose rate and cumulative environmental radiation dose. γ-ray of external radiation dose rate and the annual environmental cumulative dose in the range of 20 km was higher than in the range of 10 km and 30 km, but there were no statistical significance. Radioactive detection value of food samples were much less than the national standards, and the total radioactivity index of water source samples can be up to the national standard of drinking water.Conclusion Radioactive background in Ninghai areas adjacent to the Sanmen Nuclear Power Station was in the normal range, and there was seasonal variations. The study established baseline data for environmental background radiation before the Sanmen Nuclear Power Station running. In the future, the food sample monitoring should be focused on the artificial radionuclide ⁹⁰Sr, ¹³⁷Cs, ¹³¹I, etc.