Groups critical of the Vermont Yankee nuclear plant are observing the facility's 40th birthday by renewing their calls for the plant to be shut down.

Vermont Yankee's initial 40-year license expires Wednesday. It has won approval from the federal Nuclear Regulatory Commission to operate an additional 20 years. The state Public Service Board has yet to rule on the plant's future, but it's expected the Vernon reactor will continue operating in the meantime.

The Vermont Public Interest Research Group, Conservation Law Foundation and other groups say plant owner Entergy Corp. isn't trustworthy and that the plant is unreliable.

A pro-Yankee group, the Vermont Energy Partnership, which includes Entergy, responded by releasing a statement on a recent study showing economic harm to southeastern Vermont if the plant is closed.