SPOKANE - An emergency has been declared at the Hanford Nuclear Reservation in southeastern Washington state after a portion of a tunnel that that contains rail cars full of nuclear waste collapsed.

Randy Bradbury, a spokesman for the Washington state Department of Ecology, said officials detected no release of radiation and no workers were injured.

He says there were no workers inside the tunnel when it collapsed Tuesday morning but that nearby workers were evacuated and others who were farther away were told to remain indoors.

Hanford for decades made plutonium for nuclear weapons and is now the largest depository of radioactive defense waste that must be cleaned.

The sprawling Hanford site is about half the size of Rhode Island.