Washington Closure Hanford and its subcontractor employees have worked 6 million hours without losing a day of work to an accident.

It is the first time a Department of Energy decommissioning and demolition contractor has reached the six million hour mark, according to Washington Closure. Washington Closure is cleaning up 220 square miles of Hanford along the Columbia River.

There has not been a lost workday accident on the River Corridor Closure Project since July 2009.

"This safety achievement reflects our employees' dedication to a strong safety culture," said Carol Johnson, Washington Closure president, in a statement.