Washington ? The U.S. Energy Department evacuated some workers at the Hanford nuclear reservation near Richland on Wednesday because of a suspected breach in a container, but initial surveys detected no radioactive contamination, officials said.

The incident occurred in an area where workers have been unearthing containers of waste that had been buried for years. The site is also near a landfill where some waste is being permanently buried.

A brown absorbent material escaped from a 55-gallon drum, but an inner drum that contained a small amount of radioactive material was not believed to have leaked, and there was no environmental contamination, said Katie Larson, a Hanford spokeswoman.

Tests also found no contamination on the two workers closest to the container or on nine others who were in the area, said spokesman Calvin Dudney.

For 40 years, the 586-square-mile Hanford nuclear reservation in south-central Washington made plutonium for the nation’s nuclear weapons, beginning with the atomic bomb made by the top-secret Manhattan Project.

Today, it is the nation’s most contaminated nuclear site, with cleanup costs expected to total $50 billion to $60 billion. The work is scheduled to be completed by 2035.