Water Quality Control And Optimization Of The Second Circuit Of Tianwan Nuclear Power Station

The water quality of the secondary circuit of a nuclear power plant is related to the life of the main equipment,such as the steam generator,steam turbine,and condenser.Furthermore,it would affect the integrity of the third safety barrier of the nuclear power plant.Since the Tianwan Nuclear Power Station No.1 and No.2 units were put into operation,the water quality of the second loop has become an important technical problem that could affect the safety of the equipment during the power operation of the nuclear power plant.First,the article briefly described the main processes and monitoring indicators of the soda water cycle in the second loop of the Tianwan Nuclear Power Station,and also the effects of different water quality monitoring indicators.The importance of water quality issues for steam generators,steam turbines,generators,and condensate polishing treatment system are also discussed.The impact and requirements for major water quality control indicators in the second-line water quality online monitoring points,water quality indicators,and nuclear power plant technical specifications are also described.Secondly,the article details the condensate polishing treatment system,the addition of chemical reagents,thermal desorption,the purification of the steam generator,the leakage monitoring of the primary side of the steam generator,and the chemical cleaning of the steam generator.The technical measures to control the water quality of the second circuit were analyzed,and the causes and phenomena of the water quality deviation were also discussed.The deterioration events of water quality were analyzed from eight aspects,including:switching of circulating cooling water pump speed,failure of the dosing pump,leakage of the heat transfer tube of the condenser,failure of the purifying resin bed,deterioration of raw water quality,changes in operating conditions of the system,suction of dirty water at the vacuum boundary,and incorrect operation of personnel.Next,the article starts with the main water quality indicators of dissolved oxygen and conductivity in the condensing water,conductance of the steam generator discharge water,chloride ion,and feed water pH,and analyzes the measures for checking the deviation of the water quality in the second circuit.A new method to quickly troubleshoot water quality deviation is put forward.After that,the article proposed 10 aspects of water quality optimization control measures,and carried out a detailed discussion,including:vacuum boundary leak detection,condenser heat transfer pipe leakage treatment,condensate polishing,condensate polishing treatment system regeneration optimization,cancel the ammoniating operation,optimize the operation mode of the condensate polishing treatment system,control the water quality of the secondary circuit water supply source,transform the shaft seal water jet extractor,and maintain and flush the equipment during the unit overhaul.Finally,a comprehensive method to optimize the two-way water quality is put forward,which can effectively stabilize the two-way water quality and solve the water quality deviation problem by practice.Through the discussion of the article,the aim is to provide PWR nuclear power plants with the same type of operational control ideas,defect investigation plans,and practical operating experience references for the deviation of the water quality of the second circuit,so that they can learn from experience and continuously improve the water quality of the second-circuit system,at the same time guarantee the safe and stable operation of nuclear power plant in the secondary circuit.