The cost to dismantle the USS Enterprise will top $1 billion without Congressional action on the matter, a new report warns.

The Government Accountability Office issued the report on Thursday, saying Congressional oversight is needed to resolve conflicting nuclear regulatory jurisdiction in the matter.

The Navy's first nuclear-powered aircraft carrier, the Enterprise was commissioned in 1961, and built at a cost of $3.9 billion, in current dollars.

The Enterprise was the first and only Enterprise-class carrier ever built, and the longest naval vessel ever constructed the world. The carrier sailed more than 1 million miles over 51 years of service.

The Enterprise was the first and only Enterprise-class carrier ever built, and the longest naval vessel ever constructed the world. It is seen above in 2011

Since she was decommissioned last year, the Enterprise has been awaiting strip-down and dismantling at Puget Sound Naval Shipyard in Washington state.

Now, the GAO warns that the 'unprecedented' undertaking of dismantling and disposing of the ship could cost between $1 billion and $1.55 billion.

Under the current plan, the work on the ship's nuclear components, including the eight nuclear reactors that powered the carrier, is to be carried out by Navy workers at the Puget Sound Shipyard, with the non-nuclear components handled by a private contractor.

The GAO estimates that private contractors could do the entire job, including the nuclear components, at a cost of $750 million to $1.4 billion.

The Enterprise is seen prior to decommissioning at Naval Station Norfolk. The cost to dismantle the carrier is set to top $1 billion without Congressional action

However, a disagreement exists between the Naval Reactors office and the Nuclear Regulatory Commission as to which department would oversee the fully commercial scenario, according to the GAO.

'Naval Reactors officials assert that NRC's regulatory authority should apply to the full commercial option. NRC disagrees with this position,' the GAO report says.

The watchdog agency urged Congress to exercise its oversight and require Naval Reactors to work with NRC to break the deadlock.

Under the partial-privatization plan, nuclear waste from the ship was set for disposal at the Department of Energy’s Hanford low-level radioactive waste disposal site in the state of Washington.

Under the fully commercial plan, it is unclear from the GAO report where any nuclear waste from the ship would ultimately be disposed.