On 27 May 2020 the design lifetime of power unit No.5 of Zaporizhya NPP is going to come to the end, so, the power unit will have to go through the process of lifetime extension. To that end, an outage campaign started on 16 April 2020 on power unit No. 5 that will be somehow different from the previous ones. Unlike previous outages, this will proceed in two directions: the first dealing with maintenance and repair as such, and the second focused specifically on extension of the equipment lifetime.
The scope of works scheduled for completion during outage will include carrying out a medium repair of the reactor facility with unloading all fuel from the core; a medium repair of the steam turbine and technologically interrelated equipment, such as turbine generator – exciter – breaker, and a routine maintenance of busbars.
Also, as a part of outage efforts, a major repair of steam generator No. 1 will be conducted along with main coolant pump No. 3, including the repair of electric motor; and the repair of heat mechanical equipment of the diesel generator for the stand-by diesel power station. Two sealed multi-seat baskets loaded with 48 spent fuel assemblies will be moved to the storage site of the dry spent fuel storage facility of Zaporizhya NPP. The routine maintenance of phases ?,? and ? will be carried out on the unit transformer.
In addition, some unscheduled maintenance works will be done, which include changing self-contained air conditioners for those qualified for harsh conditions and seismic impacts; replacing the turbine condenser with a new modular-type condenser made of corrosion-resistant materials; and replacing packaged house transformer substations.
The modernization of refueling machine control systems and stand-by diesel generators will be performed along with modernization of the automatic fire alarm system. Also, during outage, new monitoring points will be arranged to provide measuring of a boron-10 isotope concentration in boric acid solution within the primary circuit systems; the control rod drives bank/individual control rod drives control system will be replaced, and the power unit will be equipped with a system for remote monitoring of prestressing forces in tendons of the prestressing containment system.
(Source: Energoatom – Image: Zaporizhya NPP)