VVER primary coolant chemistry experience and perspectives

Operational experience with VVER primary water chemistry and corrosion has been reviewed. The paper describes the results of measurements of radiation fields at primary system components and occupational doses that are compared with radiation control philosophy based on low content of cobalt in materials, no high-cobalt alloys and boron/potassium/ammonia coordinated water chemistry. The difference in water chemistry guidelines between VVERs and different current operational practices at VVER utilities are outlined. Special emphasis is given to the ammonia/hydrazine water chemistry on some VVER plants and to the next perspectives of primary coolant chemistry. (author)