RICHLAND (AP) — A new report says Congress should consider authorizing the Department of Energy to use grout to stabilize some of Hanford's radioactive waste, rather than a more expensive plan to turn it into glass.

The Government Accountability Office report was released Wednesday.

The Tri-City Herald says the report argues that grouting is less expensive than turning the waste into glass logs, and might allow the waste to be treated sooner.

But the state of Washington has long insisted that any waste disposed of at Hanford be turned into glass to best protect the environment.

The waste is left over from the production of plutonium for nuclear weapons.

The Hanford Nuclear Reservation contains the nation's highest volume of waste, about 56 million gallons stored in underground tanks. Some tanks are leaking.