美国滨海核电厂取水设施及生态影响分析和启示

Analysis of water intake structures and their ecological impacts of NPPs in American coastal areas and the enlightenment

介绍美国滨海18个核电厂址(共31台核电机组)取水设施特点及其生态影响。可以看出,在取水设施设计上,美国大部分核电厂采取了减小取水设施对水生生物的撞击和夹带的影响措施,包括采用闭式循环冷却系统;设置改进型滤网及滤网清洗和鱼回流系统;降低穿过滤网流速;设置离岸蘑菇头式取水口;减小取水流量;在取水设施外围设置屏障网等。虽然采取了一些控制措施,由历年监测数据可以看出,美国有些厂址的冷却水取水设施对鱼类、贝类等水生生物的夹带、撞击影响可能为中等水平,甚至是大的。与我国滨海厂址取水设施比较可以看出,我国大部分核电厂未采取减小取水影响的措施。并且,我国核电厂址机组数量较多,冷却水取水量较大,取水可能带来的生态影响不容忽视。因此,应结合厂址特性优化冷却水取水设施位置、设计、建造和能力,以反映最佳适用技术(BTA),最小化环境的负面影响。

The characteristics of cooling water intake structures（ CWIS） and their ecological effects of 18 American nuclear power plants（ NPPs） located in coastal areas（ a total of 31 units） are analyzed. It is found that for the designs of CWIS,most American NPPs have taken measures to reduce the impact of CWIS on aquatic organism entrainment and impingement. These measures include constructing closed-cycle recirculating system; using modified travelling screen with screen-wash system and fish return system;reducing through-screen velocities; constructing far offshore velocity caps; reducing water intake flows; and installing barrier nets at the peripheral sites of the CWIS. Based on the monitoring data of decades,it is found that with these measures,the adverse impacts of fish and shellfish impingement and entrainment are small at many NPPs,but they may be moderate or even large at a few NPPs during the CWIS operations. Compared with China＇s NPPs＇ CWIS,it can be seen that most NPPs in China do not take any measure to reduce CWIS ecological impacts. As the Chinese NPPs＇ sites have more units,more cooling water is taken by CWIS,and the ecological impacts of CWIS may be more obvious. Therefore,we need to optimize the location,design,construction,and capacity of cooling water intake structures based on the analysis of site characteristics,reflecting the best technology available（ BTA） for minimizing adverse environmental impacts.