Xcel Energy's Monticello nuclear plant will come back online this week after extensive work that included a 12 percent power uprate and equipment upgrades needed for its license extension.

Monticello nuclear plant. Source: NRCOver the course of four months, about 3,000 workers converged on the plant near Minneapolis for refueling, component replacements and other maintenance. Of the project's original $320 million budget, about 41 percent was earmarked for the uprate. As Xcel readies the plant to reenter service, though, it will also have to confront cost overruns totaling more than $267 million, the Minneapolis Star Tribune reported Monday.

The project's budget will factor into the utility's rate case before state power regulators this fall. The company declined to comment on the overages in advance of those proceedings, although in previous regulatory filings executives have cited scheduling, vendor issues and regulatory complications as pertinent factors. A plant representative told the newspaper it will release a full tally of the project's costs later, and the company has indicated it will also release further details on why the outage went over budget.

Through Northern States Power Co., Xcel operates a single General Electric Type 3 boiling water reactor at the site, according to the Nuclear Regulatory Commission. It was first licensed in 1981, and its extended license will expire in 2030. Late last year, Xcel cancelled a similar uprate for its Prairie Island nuclear plant, also in Minnesota, because of declining power demand growth in its service area.