The behaviour of ion exchange resins under the operational conditions of pressurized water reactors

Extensive users' experiences with primary coolant clean-up units based on organic ion exchange materials have proved the latter's reliability. Occasional resin finds in the primary coolant have hardly been considered so far by the operators. Especially the WWER-440 series requires dealing with these problems. Since their design does not provide for resin catchers, reliable information must be available on the consequences of the release of even larger resin amounts into the primary circuit. The hydrothermal and radiolytic decomposition products (gases, anion wastes, residual organic matter) of strongly sour and strongly basic ion exchangers based on styrene-divinylbenzene-copolymerization are discussed on the basis of laboratory data in respect of their effect on water chemistry. Three evaluated operational cases are included. In particular with regard to the release of strongly sour cation exchange resin during power operation, the mechanism can be explained by means of the time courses of selective activity concentrations and sulfate concentration/pHsub(300deg C)-value. (orig.)