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目的掌握辐照装置清污治理后的辐射环境状况,最终核实该装置治理完毕后是否符合国家相关标准而达到无限制开放。方法采用便携式X-γ剂量率仪进行现场γ辐射空气吸收剂量率监测,采用α、β表面污染仪进行现场β表面污染监测,采用高纯锗γ能谱分析仪进行~(60)Co核素比活度分析,采用四路低本底分析仪进行水中总β分析。结果辐照装置治理后γ辐射空气吸收剂量率贮源井测值为(10.0~19.9)×10~(-8)Gy/h,辐照室和附属建筑物(7.1~16.8)×10~(-8)Gy/h,辐照室以外的区域测值为(4.9~14.1)×10~(-8)Gy/h,辐照厅排水口测值为(13.5~20.3)×10~(-8)Gy/h;治理后β表面污染贮源井测值为未检出~0.06 Bq/cm~2,辐照室和附属建筑物测值为未检出~0.12 Bq/cm~2,辐照室以外的区域测值为未检出~0.08 Bq/cm~2,辐照厅排水口测值为0.17~0.25 Bq/cm~2;治理后水样中未检出~(60)Co地下水及地表水中未检出~(60)Co;水样中总β测值为0.18~0.21 Bq/L;固体样品中~(60)Co比活度辐照室出水口土壤样品中为15.4~23.0 Bq/kg,辐照室周围其他位置土壤样品中为未检出~1.7 Bq/kg,对照点土样未检出~(60)Co,贮源井表面瓷砖~(60)Co比活度为1324.7 Bq/kg,1#水池(贮源井水排放池)底泥~(60)Co比活度110 Bq/kg,2#水池底泥未检出~(60)Co。结论经过退役及环境治理,各源项均已达到《电离辐射防护与辐射源安全基本标准》(GB 18871-2002)及其他相关标准限值,整个项目区域已经达到无限制开放的要求。
OBJECTIVE To understand the radiation environment after the pollution control of the irradiation device, and finally to verify whether the device is in compliance with the relevant national standards after the treatment is completed and reach the goal of unlimited openness. Methods A portable X-γ dose rate meter was used to monitor the air dose rate of γ radiation in the field. The α, β surface contamination meter was used to monitor the β surface contamination in the field. The high purity germanium gamma spectrometer was used to measure the radioactivity of ~ (60) Co Specific activity analysis, the use of four low background analyzer for total water β analysis. Results After the irradiation device was treated, the measured values of γ ray radiation absorbed dose rate of source wells were (10.0 ~ 19.9) × 10 ~ (-8) Gy / h, irradiation room and ancillary buildings (7.1 ~ 16.8) × 10 ~ -8 Gy / h, the area outside the irradiation room was (4.9-14.1) × 10-8 Gy / h, the value of the outlet of the irradiation room was (13.5-20.3) × 10 (- 8 Gy / h; after treatment, the measured β surface contamination source reservoir was undetected ~ 0.06 Bq / cm ~ 2, and the radiation chamber and ancillary buildings were undetected ~ 0.12 Bq / cm ~ 2 The area measured outside the chamber was undetected ~ 0.08 Bq / cm ~ 2, and the radiation chamber outlet was 0.17 ~ 0.25 Bq / cm ~ 2. ~ (60) Co groundwater was not detected in the treated water samples (60) Co was not detected in surface water and 0.18 ~ 0.21 Bq / L in water samples. The content of ~ (60) Co in the solid samples was 15.4 ~ 23.0 Bq / kg, undetectable ~ 1.7 Bq / kg in soil samples at other locations around the irradiation room, ~ (60) Co in soil samples at the control point, ~ (60) 1324.7 Bq / kg, sediment of # 1 pool (storage well water discharge tank) ~ (60) Co specific activity 110 Bq / kg, sediment of # 2 pool not detected ~ (60) Co. Conclusion After decommissioning and environmental management, all the source items have reached the “basic standard for ionizing radiation protection and radiation source safety” (GB 18871-2002) and other relevant standards. The entire project area has reached the limit of opening up.