Analysis of Primary Coolant Corrosion Product Effect on Solid Waste Source Term

Corrosion product in the primary coolant is formed mainly by structure material corrosion and activated corrosion product. Under normal condition, source term of corrosion product maintains at a low level while its radioactive concentration reaches a peak value after the primary is injected with hydrogen peroxide during shutdown oxygenation operation. Following the procedure of corrosion product elimination, analysis has been made on effect which accumulated corrosion product exerts on RCV pre-filter and mixed bed demineralizer. Different primary coolant source terms and the cold shutdown peak value of corrosion product have been considered in the analysis. Under the assumption that dissolved and particle dissolved product has a fixed ratio of 1:1, the surface dose rate of RCV pre-filter varies as the different primary coolant varies. Nuclides proportion has been listed and charted based on the calculation. If cold shutdown condition has been taken in primary coolant source term calculation, then the RCV pre-filter surface dose rate will reach 345Sv/h; If primary coolant design value has been taken in source term calculation, then the RCV pre-filter surface dose rate will reach 42.2Sv/h; If 1/3 primary coolant design value has been taken in source term calculation, then the RCV pre-filter surface dose rate will reach 14.1Sv/h. For the waste resin in RCV mixed bed demineralizer, the corrosion product leaves a small contribution (less than 5%) if the cold shutdown is not considered in primary coolant source term calculation; and a contribution of over 90% if the cold shutdown is considered. The analysis provides a radiation safety analysis basis for NPP solid waste.