CHARLOTTE — A Charlotte engineering firm estimates repairs to a nuclear reactor in Florida could cost more than $3 billion and take eight years to complete.

Estimates by Zapata Inc. came at the request of Duke Energy, which inherited the plant in Crystal River, Fla., when it completed a merger in July with Raleigh-based Progress Energy.

The plant has been closed since 2009.

The newspaper reported Duke's directors said problems at Crystal River contributed to their quick dismissal of former Progress Chief Executive Bill Johnson, who had been expected to lead the combined company.

Progress has estimated it would take more than $1 billion to replace the concrete portion of the containment structure. But Zapata says unforeseen problems could push costs as high as $3.4 billion.