压水堆核电厂安全壳过滤排放系统卸压策略分析

Analysis of Depressurization Strategy of PWR Containment Filtered Venting System

压水堆核电厂可采用过滤排放的方式来应对严重事故下安全壳超压失效的风险。本文采用一体化事故分析程序,建立了压水堆(PWR)核电厂大型干式安全壳节点模型以及过滤排放通道模型,选取全厂断电(SBO)始发的严重事故序列,分别计算了无安全壳过滤排放的工况、过滤排放系统(EUF)在安全壳压力上升到安全壳设计压力0.52 MPa(a)时启动但不关闭工况下,安全壳的压力情况以及放射性物质向外释放的量。并分析EUF不同开启压力0.52 MPa(a)/0.625 MPa(a)/0.73 MPa(a),不同关闭压力0.30 MPa(a)/0.35 MPa(a)/0.40 MPa(a)对安全壳卸压的影响,分析表明:EUF系统的投入可以在避免安全壳超压失效的同时,有效减少气溶胶类放射性物质的释放;EUF关闭整定值较高时,相同时间段内开启次数相应增加,向环境的放射性释放量也较少;提高EUF的开启压力,会延迟放射性物质向环境释放的时间。

The filtered venting can be applied for the large dry containment of PWR to mitigate the risk of overpressure in severe accidents. The plant and the containment filtered venting system （EUF） were modeled, and the containment pressure and radioactive release to the environment were analyzed by using integrated safety analysis code in case of station blackout （SBO）, which was chosen for analysis, with/without EUF. and the influence of EUF close pressures, 0.30MPa（a）/0.35MPa（a）/0.40MPa （a）, and EUF operation pressures 0.52MPa（a） /0.625MPa（a） /0.73MPa（a） were investigated. The result showed that EUF system could avoid containment overpressure and reduce the release of aerosol effectively. EUF close pressure is higher, the interval of EUF operation is smaller and radioactive release is less EUF operation pressure is increased, and radioactive release to the environment is delayed.