压水堆一回路应用富集硼酸对堆芯CIPS影响的研究  

Research on the CIPS Effection of Using Enriched 10B Boron Acid in PWR Primary Coolant System

作　　者：杨建锋 秦慧敏 刘婵云 YANG Jianfeng;QIN Huimin;LIU Chanyun(Shanghai Nuclear Engineering Research&Design Institute Co.,Ltd.,Shanghai 200233,China)

机构地区：[1]上海核工程研究设计院有限公司,上海200233

出　　处：《核科学与工程》2020年第6期932-936,共5页Nuclear Science and Engineering

摘　　要：反应堆冷却剂系统(RCS)内的腐蚀积垢物(又称污垢)在燃料棒表面沉积导致轴向功率峰值向堆芯入口处偏移(堆芯CIPS现象)会影响核电厂运行,它可能导致反应堆降功率时反应堆轴向功率分布控制困难、临界工况评估出现偏差等问题。在压水堆核电厂一回路中采用富集硼酸替代天然硼酸可以降低冷却剂中的硼酸浓度,有利于控制冷却剂pH与降低锂浓度,改善水化学环境与降低材料腐蚀。本文研究压水堆一回路应用采用富集硼酸替代天然硼酸对堆芯CIPS现象的改善作用,参考美国核电厂运行研究所(INPO)发布的CIPS风险评价准则,通过堆芯硼酸沉积量评估堆芯CIPS风险程度。文章以CAP1000的前三循环为例,采用BOA程序研究不同10 B丰度下、堆芯不同时刻的硼酸沉积质量变化规律。结果表明:采用富集硼酸替代天然硼酸可以降低冷却剂中硼酸浓度,硼酸沉积质量因此大幅减少。相对于采用天然丰度硼酸,CAP1000采用40.0%10B丰度硼酸后堆芯最大沉积硼酸质量降低约80%,CIPS风险等级将由中高风险降为低风险。因此,在压水堆核电厂一回路冷却剂中采用富集10B的硼酸对堆芯CIPS现象有良好的抑制效果,有助于提升堆芯运行性能。The deposition of corrosion crud on the fuel rod surface can cause the axial power peak to shift to the core inlet,that is,Crud Induced Power Shift phenomenon(CIPS).This will affect the nuclear power plant operation.It may bring difficulty to control the axial power distribution when the reactor power is reduced or it may cause extra deviation in the evaluation of critical conditions.The use of enriched boric acid instead of natural boric acid in the primary circuit of the PWR nuclear power plant can reduce the concentration of boric acid in the coolant,which is beneficial to control the pH value of the coolant and reduce the lithium concentration,improve the water chemical environment and reduce material corrosion.This paper studies the influence on CIPS phenomenon by using enriched boric acid instead of natural boric acid in the primary loop of pressurized water reactors.With reference to the CIPS risk assessment criteria issued by the Institute of Nuclear Power Plant Operations(INPO),the CIPS risk level of the core is evaluated by the amount of boric acid deposited on the fuel rod surface.Taking the first three cycles of CAP1000 as an example,the BOA program is used to study the changes of boric acid deposition quality at different 10 B abundances and at different times in the core.The results show that the use of enriched boric acid can reduce the concentration of boric acid in the coolant,and the quality of boric acid deposition is therefore greatly reduced.Compared with the use of natural abundance boric acid,the maximum core deposited boric acid quality is reduced by about 80% with the use of40.0%10 B abundance boric acid,and the CIPS risk level will be reduced from medium high risk to low risk.Therefore,the use of 10 B enriched boric acid in the primary loop coolant of the PWR has a good inhibition effect on the CIPS phenomenon and is helpful to improve the core operating performance.

关 键 词：压水堆 富集硼 CIPS 

分 类 号：TL364.4[核科学技术—核技术及应用]