RICHLAND, Wash. -- Employees of Washington River Protection Solutions have worked more than 5 million hours without a work day lost to injury.

"This is unprecedented in Hanford's tank farm history," said Mike Johnson, president, in a statement.

Employees have worked 520 days or more than 15 months without an injury that required a day away from work.

The Hanford contractor for the tank farms, where 56 million gallons of radioactive waste is held in underground tanks, has about 1,400 employees.