核设施烟囱气态流出物取样代表性验证的技术要求研究

Study on qualification methods and technologies of sampling representativeness of airborne effluents from the stacks of nuclear facilities

核设施的排放烟囱都设有连续取样和在线监测系统,对流出物中排放的气载放射性活度进行测量,以判明气态流出物排放是否满足管理限值要求,并及时发现污染异常,提供报警。但是,取样和监测系统中气态流出物的取样是否具有代表性,将直接影响流出物测量的准确性。ISO标准(ISO 2889—2010)和美国标准(ANSI/HPS N13.1—2011)都对核设施气态流出物取样监测的有关性能,提出了详细的量化指标和判定方法。本文在对上述标准编写的技术背景和国内外所开展的相关工作进行调研的基础上,研究分析了这些标准推荐的各项性能指标和验证方法。

Nuclear facilities are equipped with continuous sampling and on- line monitoring systems for measuring airborne radioactivity discharged from the stacks to determine if airborne effluent emissions would meet the regulatory requirements. These systems are also used for timely detection and alarm of abnormal releases. However,measurement accuracy would be directly affected by the representativeness of sampling from airborne effluents. Both the ISO standard ISO 2899—2010 and ANSI / HPS N13. 1—2011 standard have established specific quantitative criteria on the performance of sampling and monitoring systems for airborne effluents from nuclear facilities. In this paper,technical background for the preparation of the above standards and the relevant work conducted both at home and abroad are reviewed. The quantitative criteria and validation methods recommended in these standards are analyzed.This can provide guidance for demonstration and implementation of sampling representativeness of airborne effluents. Meanwhile,the study can also provide references for the design of vents and sampling systems of airborne effluents in nuclear facilities.