General Dynamics received a $146 million contract modification from the U.S. Navy to increase design support requirements for Columbia-class submarines.

The contract's tasks include vendor component and technology development, engineering integration, concept design studies, cost reduction, and prototype manufacturing. General Dynamics will also conduct engineering analysis and cost evaluations for the next-generation submarine program.

The work will be performed in Groton, Conn.; Newport News, Va.; Quonset, R.I.; and Bath, Maine. The U.S. Department of Defense expects the work to be complete by September 2017. The Naval Sea Systems Command in Washington, D.C., is listed as the contracting activity.

Columbia-class submarines, formerly known as Ohio Replacement submarines, are future vessels designed to replace the Trident-armed Ohio-class submarines. The ballistic missile vessels are being designed to be propelled with a nuclear reactor, enabling unlimited range.

Construction on the vessels is expected to begin in 2021, with the first Columbia-class submarine entering service in 2031.