PORTLAND — The Navy spent about $71 million on cleanup, planning and initial repairs on the fire-damaged USS Miami before scuttling plans to restore the nuclear-powered submarine.

The Navy intended to repair the attack submarine, damaged last year, at Portsmouth Naval Shipyard and return it to duty before the discovery of additional cracks in pipes drove the estimated repair costs up from $450 million to $700 million. The Navy announced last month it was scrapping plans to repair the Miami because of the higher estimates coupled with mandated budget cuts.

The $71 million expense consisted mostly of damage assessment, planning, repair materials and some initial repair efforts, along with $7 million for cleanup. The figure was provided at the request of The Associated Press.

Loren Thompson, defense analyst at the Lexington Institute, said the waste of taxpayer dollars underscores the challenges facing the Navy as it shifts priorities to meet reduced funding.

“The figure illustrates the kind of waste that results when unpredictable budget pressures force the military services to change their plans,” Thompson said Friday.

The Miami was severely damaged by a fire set by a shipyard worker in May 2012 while it was in dry dock during a 20-month overhaul at the Kittery, Maine, shipyard.

The submarine remains in the same dry dock, but it won’t be restored. Instead, shipyard workers will remove fuel from the nuclear reactor and make enough repairs so that the submarine can be towed to Puget Sound Naval Shipyard in Washington State, where it’ll eventually be cut up for scrap. Inactivation costs are estimated to be $54 million, the Navy said.

The Navy had intended to repair the Miami with a goal of returning it to service in 2015. The Navy said it would be cost-effective because the 23-year-old submarine could serve another 10 years. But with the higher cost estimate, the Navy decided it made more sense to shift limited dollars elsewhere.

The Naval Sea Systems Command said the expenditure on cleanup, repairs and assessment wasn’t a total loss because part of the spending supported both the repair and inactivation. Materials procured for repair is being assessed for use in maintenance and repair of other active-duty submarines.

Paul O’Connor, president of the Metal Trades Council, blamed Congress and the federal sequestration cuts for the decision to scuttle repairs. The Navy wanted to repair the sub, he said, but just couldn’t afford it.

“The waste is Congress not being clear in the budget. We haven’t had a working budget for years. Every year is a continuing resolution from the previous year. It’s no way to run a business. It’s no way to defend our nation,” O’Connor said Friday.

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