How Will the Technical Failure at Kozloduy’s Sixth Unit Impact Energy Security Until the End of 2025?

In late July 2025, the sixth unit of Kozloduy Nuclear Power Plant was shut down due to a technical failure in the cooling system of its fourth parallel generator. The unit, with a capacity of 1,000 MW, supplies about 15% of Bulgaria’s total electricity. This temporary outage presents a critical test for the country’s energy system.

Energy dependence and risk scenarios

Nuclear energy is the backbone of Bulgaria’s energy security — units 5 and 6 together produce over 34% of the country’s electricity. The shutdown of one of them creates an urgent need to compensate for the shortfall with alternative sources like gas-fired plants, coal power, and electricity imports.

Possible scenarios until the end of 2025

Scenario A: Rapid recovery

If repairs are completed within 1–2 weeks, Bulgaria can avoid significant deficits and price hikes. The national energy operator has reserve capacities that can be activated.

Scenario B: Medium-term repair

A repair lasting 3–6 weeks will require increased electricity imports from Romania and Greece. Wholesale prices may rise by 5–10%, with industry bearing the brunt.

Scenario C: Long repair and market impact

If complications extend repairs beyond six weeks, there may be pressure on household price caps. This could accelerate political calls for investments in new capacities and greater reliance on renewable energy.

Investments and long-term solutions

Alongside short-term measures, Bulgaria has already taken steps to diversify its nuclear fuel supply through contracts with Westinghouse, reducing dependence on Russian deliveries and enhancing long-term energy security. The potential construction of new capacities — including small modular reactors — is back on the agenda.

Conclusion

The failure of Kozloduy’s sixth unit is a serious challenge for Bulgaria’s energy system. Whether it turns into a short-lived incident or exposes systemic weaknesses depends on the speed and efficiency of repairs and the energy sector’s readiness to respond.

Disclaimer:
This article is an analytical review by the BurgasMedia editorial board and reflects the opinion of an expert group based on current political, economic, and social developments.
The conclusions presented are not predictions or factual statements, but a hypothetical interpretation of possible scenarios.
The publication is not responsible for any discrepancies with future developments and encourages readers to form independent judgments based on verified sources.