Long Island Lighting Co.'s board of directors unanimously approved an agreement with the state under which the completed but unused Shoreham nuclear power plant would be torn down.

It would be the first time in the nation that a completed nuclear plant was abandoned.Under the proposal approved Wednesday, the utility would continue as a privately owned company and be provided with annual rate hikes of about 5 percent over 10 years.

The agreement is subject to the approval of various state agencies and the Legislature. It calls for the utility to sell the $5.3 billion plant to the state for $1. The plant would then be torn down.