某深埋输水隧洞放射性环境地质调查与评价

Geological Investigation and Evaluation of Radioactive Environmental in a Deep-Buried Water Transfer Tunnel

为探究某深埋输水隧洞穿越地层的放射性环境质量,采用原位测试和样品分析等手段,研究隧洞施工期的不利因素。结果表明:隧洞地表沿线的放射性元素含量在背景值变化范围内,未发现放射性异常现象。隧洞穿越的7个钻孔内γ总量和地温测井的结果表明:孔内核素放射性水平较低,基本处于豁免水平,但地温存在异常区域,施工期务必引起重视。钻孔目的层的岩心放射性核素活度浓度低,属于豁免范围内,孔内地下水放射性水平低,满足Ⅲ类地下水要求。辐射防护的计算结果显示,隧洞段地表沿线γ有效剂量当量为0.15 mSv/年,符合国家要求。隧洞段内照射指数和等效镭浓度符合约束值,ZK16钻孔的目的层外照射指数略高于标准值。因此,地下隧洞在施工期需着重关注洞内放射性水平,在辐射异常地段加强岩石采样与分析工作,以保证施工安全。

In order to explore the radioactive environmental quality of a deep-buried water transfer tunnel,the unfavorable factors during tunnel construction are identified by in-situ testing and sample analysis.The content of radioactive elements along the tunnel surface is within the range of background values,and no radioactive anomalies are found.In seven boreholes where the tunnel crosses the results ofγtotal amount and ground temperature logging show that the radioactivity level in the hole is low and basically at the exemption level,but there are abnormal areas in the ground temperature,so attention must be paid during the construction period.The activity concentration of radionuclides in the core at the target layer of the borehole is low,which falls within the scope of exempted activity concentration,and the radioactivity level of groundwater in the hole is low,meet the requirements of third types groundwater.The calculation results of radiation protection show that along the surface of the tunnel section the effective dose equivalent ofγis 0.15 mSv/a,accord with the national requirements.The internal exposure index and radium equivalent activity in the tunnel section which conform to the constraint value,the external exposure index at the target layer of borehole ZK16 is slightly higher than the standard value.Therefore,during the construction of the underground tunnel,it is necessary to pay attention to the radioactive level in the tunnel,and strengthen the sampling and analysis of rock samples in the section with abnormal radiation to ensure the construction safety.