Analysis and Optimization of Early Post-overhaul Origin of Wastewater Neutralization Tank of Units 3&4 in Qinshan Nuclear Power Company
Due to the requirements of technological specifications for water quality,during a period of time after shutdown of steam turbines,secondary feedwater needs to be first discharged to wastewater neutralization tanks for treatment.It was found during the 408 overhaul of Unit 4 in Qinshan Nuclear Power Company a rapid increase of liquid level in the wastewater neutralization tank,generating a large amount of wastewater and posing a risk of overflow.This paper reports the causal identification through the method of process analysis observing the effects of the drainage of condenser and the drainage of circulating water pipe pit after shutdown of the steam turbines.Based on detailed calculations of each incoming water quantity,the paper proposes optimization measures,such as delaying the implementation of administrative isola-tion,directly discharging steam generator waste with acceptable quality after desalination bed treatment,and throttling cooling water.The proposed countermeasures were implemented and verified in the 309 overhaul of Unit 3,which helped to solve the problem of incoming water of wastewater neutralization tank and reduce wastewater generation and manpower loss.This process analysis method performs well in solving the weaknesses in unit service and has certain reference signif-icance to similar problems.
major repairsecondary drainageneutralization tankoptimization