The state of Washington has issued a $1 million fine to the Hanford Nuclear Reservation in eastern Washington for restricting access to critical data.

The Washington Department of Ecology issued the fine on Monday to the Hanford Nuclear Reservation, which is owned by the U.S. Department of Energy.

Hanford for decades made plutonium for nuclear weapons, and the site is now engaged in cleaning up some of the most radioactive sites in the world. The Department of Energy is expected to appeal the fine.