SPOKANE, Wash. -

Few of the U.S. Department of Energy workers who are helping build a plant to treat the most dangerous radioactive wastes at a nuclear site in Washington state feel they can openly challenge decisions made by management.

That's according to a recent survey by the department, which shows only 30 percent of its employees at the Hanford Nuclear Reservation feel they can openly question their bosses.

The survey results, obtained Tuesday by The Associated Press, were somewhat better for managers at the plant. It shows 65 percent of managers who responded felt they could openly challenge decisions by higher-level managers.

Democratic Sen. Ron Wyden of Oregon says the results show recent allegations of retaliation against Hanford workers who raised safety concerns made other workers less likely to come forward.

Hanford is engaged in a multi-decade cleanup of the nation's largest collection of nuclear waste.