秦山核电厂气态流出物监测系统的研究及其改进

Research and Improvement of Monitoring System for Gaseous Effluent in Qinshan Nuclear Power Plant

秦山核电厂气态流出物取样监测系统采用了较长的水平取样管和垂直取样管,使核电站气态流出物排放监测存在设计上的缺陷。由于取样管道过长(特别是水平取样管道),会造成气溶胶和碘取样过程的管道沉积损失。改进后,将气溶胶和碘的取样监测系统移至烟囱底部的校正室,取消了长度为85.4m水平取样管线,取样管改为只有70.6m的垂直管。试验测试及评价结果表明:放射碘的取样校正因子可取作1.65。对于放射性气溶胶,按最保守的估计,事故工况下,其校正因子最大也不可能大于1.65;在正常运行期间,气溶胶粒子均以小粒径为主,可将校正因子取作1.1。

The long horizontal and vertical sampling pipelines are used in the gaseous radioactive effluent monitoring system in Qinshan Nuclear Power Plant, so there is design deficiency for the monitoring of gaseous effluent. The long sampling pipelines, especially horizontal pipe, will result in the losing of sampling particulate and iodine. By means of modification, the sampler for particulate and iodine is moved into the small corrective room at the bottom of the stack, therefore, 85.4 meters long horizontal sampling pipe is cancelled, only 70.6 meter long vertical sampling pipe is reserved. The test and assessment result indicated that the corrective factor of the radioactive iodine sampling is 1.65. For radioactive particulate, according to conservative estimate, the corrective factor is less than 1.65 under accident condition. During normal operation, the particulate is consisted of tiny particles, and the corrective factor is 1.1.