长燃料循环对核电厂蒸汽发生器缝隙化学的影响及对策  

Influence of Long Term Fuel Cycle on Steam Generator Crevice Chemistry in Nuclear Power Plants and Countermeasures

作　　者：蔡金平 田民顺 池利生[2] CAI Jinping;TIAN Minshun;CHI lisheng(Fujian Fuqing Nuclear Power Co.,Ltd.,Fuzhou of Fujian Prov.350318,China;Fujian Key Laboratory of Fuel and Materials in Clean Nuclear Energy System,Fujian Institute of Research on the Structure of Matter,CAS,Fuzhou of Fujian Prov.350002,China)

机构地区：[1]福建福清核电有限公司,福建福清350318 [2]福建省清洁核能系统燃料与材料联合重点实验室,中国科学院福建物质结构研究所,福建福州350002

出　　处：《核科学与工程》2020年第5期783-791,共9页Nuclear Science and Engineering

摘　　要：国内核电厂将燃料循环周期从12个月延长到18个月,提升了机组的能力因子和经济效益,但是迁移、沉积在蒸汽发生器内的腐蚀产物及在缝隙内可溶性杂质累积浓度也随之增加,这对蒸汽发生器的安全运行带来了负面影响。本文根据蒸汽发生器缝隙隐藏与返出原理,研究了核电厂实施长燃料循环对缝隙化学和传热管的影响,揭示当燃料循环延长到18个月后,缝隙内主要杂质Na^+、Cl^-和SO4^2-浓度累积值增加2倍,导致传热管风险因子增加2倍以上,因此传热管腐蚀风险明显地上升了。这些研究结果结合缝隙内可溶性杂质累积控制和传热管风险评估方法,提出采用低功率浸泡、添加分散剂、优化二回路化学控制,水力清洗,化学清洗等对策,目的是最大程度降低因实施长燃料循环对蒸汽发生器所造成的负面影响,供实施长燃料循环的核电厂运行时参考。Domestic nuclear power plants usually extend a fuel cycle from 12 months to 18 months,which can increase the unit capacity factor and improve economic performance.However,the corrosion products deposited in the steam generator and the cumulative concentrations of soluble impurities in the crevices could be higher in a 18-month fuel cycle than those in a 12-month fuel cycle,which would have a negative impact on the safe operation of steam generators.This paper investigates the influence of an extended fuel cycle on the crevice chemistry and steam generator tubes based on mechanism of hideout and hideout return.The results reveal that when a fuel cycle is extended to 18 months,the cumulative concentrations of main impurities Na^+,Cl^-and SO4^2-in the crevices increase by a factor of two,leading to an increase in tube exposure factor by more than a factor of two,thus increasing the risk in corrosion of steam generator tubes.Based on the results obtained in the present study,in combination with integrated exposure control of soluble impurities in the crevices and evaluation for steam generator tube exposure,a number of countermeasures are proposed,such as hot soak,adding dispersant,optimization of secondary water chemistry control,sludge lancing,and chemical cleaning to mitigate the negative impact of implementing the long term fuel cycle in nuclear power plants.These countermeasures could be guidance for the safe operation of nuclear power plants.

关 键 词：蒸汽发生器 缝隙化学 长燃料循环 腐蚀 对策 

分 类 号：TL48[核科学技术—核技术及应用]