某排风中心室外通风管沟放射性污染源项调查

Investigation of radioactive source term in outdoor ventilation ducts of a certain exhaust air center room

目的对某排风中心室外通风管沟进行放射性污染源项调查,以确定通风管沟及周围土壤污染范围、污染程度(包括污染核素和活度)、放射性废物的总量,为该设施后续的退役工作提供源项数据。方法采用一系列调查及监测的优化组合,制定了源项调查的组合方法流程图,利用现场监测、取样、实验室分析、废物估算等手段对该设施进行了源项调查。结果通风管沟周围土壤有局部污染,主要污染区域为T7、T17区域,主要放射性核素为137 Cs和90 Sr;拆除时会产生放射性固体废物量约为456.1 m3,其中极低污染土约为312 m3,低污染土约为56 m3,其它放射性固体废物约为88.1 m3,放射性废液体积约3.0 m3。结论在该设施后续的退役过程中,应采取适当的辐射防护措施,并对废物进行合理分类,以实现辐射防护最优化及废物最小化。

Objective Radioactive source term in outdoor ventilation ducts of a certain exhaust air center room was investigated.The contamination extent and degree(including contaminated nuclides and activity)of soil around the ventilation ducts as well as the total quantity of radioactive waste were determined,which provided important radioactive source term data for the decommission of the facility.Methods The optimization combination of a series of investigation and monitor methods was carried out.In this process,the combined method flow chart of source item survey was developed,and by use of on-site testing,sampling,analysis,waste estimate and other means,the source term investigation work was done.Results The result showed that there were radioactive contaminations in parts of the surrounding soil,among which the main contaminated parts were T7,T17 area,and the main radioactive nuclides were 137Cs and 90 Sr.The contamination would bring about 456.1 m3 solid waste,among which very low polluted soil was about 312 m3,low polluted soil was about 56 m3,and the other solid radioactive contaminated waste was about 88.1 m3.In addition,radioactive water was about 3.0 m3.Conclusion This work indicated that proper radioprotection steps should be taken during the decommission of this facility,and the waste should be assorted reasonably to realize optimization of radioprotection and minimization of waste.