Present status and recent improvements of water chemistry at WWER and RBMK plants

摘要

The current Russian nuclear program includes life extension of the oldest plants and construction of new plants in Russia and abroad. Water chemistry is an important contributor to reliable plant operation, safety barrier integrity, plant component lifetime, radiation safety, environmental impact, etc. Primary and secondary system water chemistry standards of Russian plants have been modified to meet the new safety standards. Some changes in new water chemistry specifications are based on investigations and studies of recent abnormal events at WWER and RBMK plants related to corrosion problems, flow assisted corrosion, corrosion cracking, foreign material intrusion, equipment fouling, chemistry control deviations, -etc. Traditionally, the primary and secondary system water chemistry at WWER and RBMK plants differ significantly from water chemistry at Western designed PWRs and BWRs due to different design and development history. Co-operation between Russian and Western organisations and specialists under some recent joint programs, e.g. within the framework of EU-RF project on safety issues for future reactors, brought about useful findings from both WWER and PWR chemistry control programs, which may be successfully implemented in future projects and at PWR and WWER plants in operation.