NORTHAMPTON, Mass. – The head of New Hampshire’s emergency management services said Thursday he’s confident the Vermont Yankee nuclear plant is safe, but he told its managers to do a better job communicating with state officials and the public when problems arise.

There was an equipment failure Monday at the plant, but operators detected the problem immediately and shut down the reactor. The plant was started up again Thursday afternoon.

But miscommunication between Vermont Yankee and officials in New Hampshire led to confusion about what happened and how big the problem was.

“I’m not concerned about safety issues at Vermont Yankee,” said Bruce Cheney, New Hampshire’s director of the Division of Emergency Services. “I am concerned about having better communications and more complete communications with them.”

As required by protocol, plant officials contacted emergency managers in New Hampshire and Massachusetts to alert them to the problem. The plant is located in Vernon, Vt., just across the Connecticut River from Hinsdale, N.H., and a few miles from the Massachusetts border.

The plant operator who notified Cheney said the problem was not an emergency. But the plant’s report to the Nuclear Regulatory Commission used the phrase “catastrophic failure.”

Media organizations seized on the phrase, and Cheney’s boss, New Hampshire Gov. John Lynch, accused the plant of failing to disclose all the facts. He called for a full accounting of what happened.

Cheney met Thursday with Vermont Yankee’s vice president, Jay Thayer, during a previously scheduled conference in Northampton that also was attended by emergency management directors from Vermont and Massachusetts.

Thayer said “catastrophic failure” is an engineering term used to describe a piece of equipment that simply has stopped working.

“If something is broken, or it’s come apart, it’s a catastrophic failure,” he said. “What happened here happened in milliseconds.”

He conceded that the phrase may have set off undue alarms and pledged to better explain problems to state officials when they arise.

“We need to take things to a level of more common understanding,” Thayer said. “This type of language probably needs a level of translation.

“We’re working with our control room operators to give better descriptions than that,” he said.

The incident involved a high-voltage short circuit caused by the failure of an electrical insulator in the switchyard that moves power from the plant to the electric grid. Plant equipment detected the problem automatically and shut down the reactor immediately, officials said.