U.S. Sen. Maria Cantwell has asked the Department of Energy to pay a 10-year-old debt of $6.8 million to Washington state.

Cantwell, D-Wash., sent a letter to Energy Secretary Spencer Abraham, telling him to send "without further delay" the payment-equal-to-taxes.

The money is due from the late 1980s when Hanford was one of three sites being considered for a national repository for nuclear wastes. Eventually, DOE picked Yucca Mountain, Nev., to receive commercial spent nuclear fuel and federal high-level radioactive wastes from across the nation.

Under the Nuclear Waste Policy Act of 1982, states being considered for the repository were entitled to receive federal money equal to the taxes a private company would have paid for sampling and studying a site for a nuclear waste repository.

Washington levied such a payment against DOE in 1993 to make up the equivalent of unpaid state business and occupation taxes.

With interest, that has grown to $6.8 million.

"For 10 years, (DOE's Office of Civilian Radioactive Waste Management) has denied responsibility for paying Washington's Business and Occupation Tax for activities carried out at the Hanford reservation," Cantwell wrote.

Her letter said DOE's Office of Hearings and Appeals ruled on June 25, 2002, and on July 16, 2003, that DOE must make the payment.

Cantwell's letter told DOE to explain why it has not paid the money and asks when it will.

DOE officials in Washington, D.C., were unavailable to comment on the issue Wednesday.