Prospects for zinc injection in Russian design reactors

The experience with operation of a Russian Model VK-50 boiling reactor has shown a positive effect of zinc presence in the primary coolant on the radiation situation and corrosion resistance of reactor materials since 1960s. Selective corrosion of brass tubes in turbine condenser and low pressure heaters caused presence of zinc in the coolant. Replacement of brass tubes to copper-nickel tubes resulted in deteriorated radiation situation due to replacement of ⁶⁵Zn as a major source term with the more hazardous ⁶⁰Co. In 1990, Russia's nuclear ministry was asked to deliver a large amount of depleted zinc to reduce radiation exposures at US BWRs exhibiting primary piping cracking. In the early 1990s, Zelenogorsk's Electrochemical plant launched commercial production of top quality depleted zinc. Nowadays, Russian depleted zinc is delivered in many BWRs and PWRs worldwide. The current depleted zinc production capacities in Russia are also sufficient for Russian design water cooled nuclear reactors too. Zinc injection programs are currently under consideration at some Russian design reactors. Zinc injection programs at Russian design VVER and RBMK reactors could be improved as compared with current practice at PWRs and BWRs thanks to some water chemistry features. (author)