Unit 5 at Bulgaria’s Kozloduy Nuclear Power Plant has returned to electricity generation after completing its scheduled annual maintenance outage. The 1,000 MW reactor was reconnected to the national grid on Monday, 15 June. The restart followed authorization from the Nuclear Regulatory Agency, after it reviewed the maintenance results and approved the unit’s return to service.
The maintenance outage began on 9 May and covered inspection, repair, and modernization activities for continued safe and efficient operation of the unit. In addition to routine maintenance work, engineers carried out upgrades linked to long-term operational sustainability of the reactor.
Fuel reload using Westinghouse-supplied assemblies
A central part of the shutdown involved loading fresh nuclear fuel supplied by Westinghouse. The reload supports the third consecutive operating cycle using RWFA fuel assemblies. Bulgaria is continuing efforts to diversify fuel sources for its VVER-1000 reactors.
The fuel diversification program was initiated in 2024. Plant officials said this step is intended to strengthen fuel supply security through reduced reliance on a single supplier.
Alternative fuel source for EU VVER-1000 reactors
Bulgaria has become the first European Union member state to introduce an alternative fuel source for this reactor type. Officials noted that the initiative has drawn strong attention from the broader European nuclear industry.
They pointed to growing concerns across Europe over fuel security and supply chain resilience in recent years.
