Analysis of Abnormal Rise of Fluorion in the Primary Circuit of PWR
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摘要: 针对某压水堆核电站大修后反应堆冷却剂系统(RCS)氟离子异常升高的问题,本文通过化学分析干扰因素排查、取样代表性验证排查、RCS补水水质排查、工艺系统添加物排查、燃料包壳引入杂质排查、化学辅材使用情况排查以及各相关系统水质排查,经排查之后得出原因是:建筑安装期间用于换料水池和乏燃料池不锈钢表面酸洗钝化的酸洗钝化膏未被清洗彻底而残留于不锈钢表面,经辐照分解后产生的氟离子对一回路水质造成污染,并造成净化离子床氟离子饱和,失去净化能力,换水过程中持续向一回路释放氟离子。Abstract: In view of the abnormal increase of fluorion in the primary circuit of a PWR nuclear power plant after overhaul, in this paper, the interference factors of chemical analysis, the representative verification of sampling, reconnaissance of RCS makeup water quality, additives in the process system, impurities in fuel cladding, the use of chemical auxiliary materials, and water quality of related systems are investigated, the results show that the acid pickling passivation paste used for pickling passivation of stainless steel surface in the refueling pool and spent fuel pool during during construction and installation is not cleaned thoroughly and remains on the surface of stainless steel. The fluorion generated after irradiation decomposition pollutes the primary water, and causes the fluorion in the purification ion bed to be saturated, losing the purification ability of fluorion, and continuously releasing fluorion into the primary water during water exchange.
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表 1 取样代表排查监测数据
Table 1. Sampling Representative Monitoring Data
监测点 取样日期 阴离子浓度/(μg·L−1) 备注 F− Cl− SO42− RCS-HL 2020-02-28 31.8 9.8 3.0 A流道手套箱取样 RCS-HL 2020-02-28 32.0 9.8 2.6 A流道手套箱取样 RCS-HL 2020-02-28 31.3 9.4 2.2 A流道手套箱取样 ACC-B 2020-03-12 6.1 4.4 5.1 B流道手套箱取样 ACC-B 2020-03-12 7.2 4.4 3.4 A流道手套箱取样 RCS-HL 2020-03-13 32.0 5.5 2.1 B流道手套箱取样 表 2 A-EHT、B-EHT大修期间氟离子浓度监测情况
Table 2. A-EHT, B-EHT Fluorion Monitoring During Overhaul
取样日期 A-EHT氟离子
浓度/(μg·L−1)取样日期 B-EHT氟离子
浓度/(μg·L−1)2020-02-11 8.3 2020-03-08 13.1 2020-02-13 9.8 2020-03-12 3.5 2020-02-14 7.6 2020-03-12 3.5 2020-02-15 12.5 2020-03-12 14.4 2020-02-17 5.4 2020-03-17 6.3 2020-02-21 7.7 2020-03-17 7.8 表 3 燃料包壳表面氟离子浓度检测结果
Table 3. Test Results of Fluorion on Fuel Cladding Surface
公司名称 样品编号 氟离子浓度/
(μg·dm−2)西屋公司 1 3 西屋公司 2 3 西屋公司 3 3 国核锆业 4 1 国核锆业 5 3 国核锆业 6 1 表 4 某型不锈钢酸洗钝化膏主要成分表
Table 4. Main Components of a Type of Stainless Steel Passivation Paste
成分 含量/% 硝酸 7~20 硝酸盐 7~20 氢氟酸 5~15 增稠剂 10~30 缓蚀剂 0.5~5 表 5 机组A CVS净化效率
Table 5. Unit A CVS Purification Efficiency
日期 入口氟离子浓度/
(μg·L−1)出口氟离子浓度/
(μg·L−1)净化效
率/%2020-01-25 8.8 5.1 42.0 2020-02-28 31.8 32.5 −2.2 2020-03-03 32.1 33.1 −3.1 2020-04-13 26.0 29.1 −11.9 2020-05-11 21.0 20.7 1.4 2020-06-08 22.6 22.9 −1.3 2020-07-06 21.7 21.6 0.5 2020-08-03 18.8 20.1 −6.9 2020-09-28 16.9 18.4 −8.9 2020-10-26 17.3 19.7 −13.9 表 6 机组B CVS净化效率
Table 6. Unit B CVS Purification efficiency
日期 入口氟离子浓度/
(μg·L−1)出口氟离子浓度/
(μg·L−1)净化效
率/%2020-02-19 1.0 1.0 0 2020-02-28 1.0 1.3 −30.0 2020-03-02 1.0 1.3 −30.0 2020-04-07 6.5 8.4 −29.2 2020-05-11 16.5 17.3 −4.8 2020-06-08 15.5 14.4 7.1 2020-07-07 20.2 20.1 0.5 2020-08-05 18.1 19.2 −6.1 2020-08-31 14.4 18.3 −27.1 2020-09-28 14.9 15.0 −0.7 2020-10-26 15.0 15.5 −3.3 -
[1] EPRI. PWR primary water chemistry guidelines Volume 1, revision 7[Z]. Ft. Lauderdale: Electric Power Research Institute, 2012. [2] 张芳, 李宇春, 朱志平, 等. 电厂水处理技术[M]. 北京: 中国电力出版社, 2014:103-105.