A wildfire burned an estimated 3,000 acres on the Hanford nuclear reservation early Saturday morning, and a larger fire was burning uncontained on Saddle Mountain.
The nuclear reservation fire burned to the east of Highway 240 in the southern end of Hanford, said Rae Moss, spokeswoman for Hanford contractor Mission Support Alliance.
No buildings or areas with radioactive waste were involved, she said.
The fire was discovered about 3:20 a.m. and the Hanford Fire Department had it contained at 6:50 a.m., according to Mission Support Alliance
Highway 240 was closed from Highway 225 to the Highway 24 until about 4:30 a.m., according to the Washington Department of Transportation.
Hanford workers were told to use the Wye Barricade entrance to the site just north of Richland rather than the Yakima Barricade secure entrance.
The cause of the fire has not been announced, but a thunderstorm passed through the Mid-Columbia overnight.
The thunderstorm was the likely cause of two more fires that started on the Saddle Mountain area of the Hanford Reach National Monument north of the Columbia River. The reach includes the original security zone around the nuclear reservation.
The fires started about 10:30 p.m. Friday and merged.
The combined size was estimated at about 12,000 acres, with 30 percent of the fire contained at 10 a.m. Saturday.