Groton — The Navy is expected to award Electric Boat the two major contracts, totaling about $450 million, to repair the USS Miami, severely damaged in a fire last May.

The Navy will award a planning contract this month to support the engineering that will guide the repairs and to purchase parts for the Groton-based submarine. The repair contract will be awarded in the spring.

In a recent briefing on the repairs, the Navy told congressional staffers that EB will receive both contracts because of the extensiveness of the repairs and because of the company's expertise as the manufacturer of the submarine, according to a staff member who attended the meeting and asked not to be identified.

The work will be a joint effort between EB and the Portsmouth Naval Shipyard, since the submarine is staying at the naval shipyard, where the fire occurred, the staffer said.

The first contract will be about $100 million, followed by an award of roughly $335 million in the spring, the person said, and EB will have, at its peak, 300 employees working on the project.

"We'd be pleased to support the Navy if we're awarded the contract, and we're still standing by to see whether or not we get it," Electric Boat spokesman Robert Hamilton said Wednesday.

A spokeswoman for the Naval Sea Systems Command said she could not confirm the recipient of the contract until it is awarded.

The Miami (SSN 755) was in a dry dock at the Maine shipyard for maintenance and upgrades when it caught fire May 23 and burned until the next day. The shipyard worker accused of setting the submarine on fire has been charged with arson.

The repairs are much more significant than those Portsmouth had planned for the overhaul and involve rebuilding sections of the boat, the staffer said. The person also said the USS Providence, which was scheduled for maintenance at the shipyard, may now go to EB for the work since the Miami will remain at the Maine shipyard for longer than expected.

EB built the Miami, a Los Angeles-class submarine, for $900 million. It was commissioned at the Naval Submarine Base in Groton in 1990 and arrived at the Portsmouth shipyard in March for a 20-month overhaul.

The Navy has said it will fix the submarine by April 30, 2015, because the Miami still has 10 years remaining in its roughly 30-year service life, making it eligible for at least five more deployments.

j.mcdermott@theday.com