The state and region put emergency response plans and procedures to the test Tuesday during an exercise built around a release of potentially dangerous levels of radioactivity after two fictitious accidents at Millstone Power Station.

"We have just gotten a notice from the plant that they have a general emergency, involving the actual or potential release off-site of large amounts of radioactivity," Reid Burdick, New London's emergency management director, announced shortly after 11 a.m. to city police, fire and other officials assembled in the emergency operations center for the drill.

Ten communities in Millstone's Emergency Planning Zone participated — Lyme, Old Lyme, East Lyme, Waterford, New London, Groton City, Groton Town, Ledyard, Montville and Fishers Island. Based at the state armory in Hartford, 11 departments provided the state response, along with the Coast Guard, the American Red Cross, New York state emergency management officials, the Nuclear Regulatory Commission and the Federal Emergency Management Agency.

Emergency drills take place annually, but this year's was an enhanced exercise that is being evaluated by FEMA and the NRC. The two federal agencies will review the drill during a briefing for local officials and the public at 1 p.m. Friday at Waterford Town Hall.

"The focus is making sure that the utility knows how to run a good exercise and knows how to self-evaluate it," said Steve Barr, senior emergency preparedness inspector at the NRC, who spent the six-hour exercise observing Millstone staff.

The scenario began at 8:17 a.m. with the declaration of an "unusual event," the lowest of three levels of emergency declarations. Towns and the state were alerted that a spent fuel assembly from the Unit 3 reactor had been dropped while it was being moved into the cooling pool, knocking off its nozzle and dislodging an adjacent assembly in the pool. The accident resulted in a small, filtered release of radioactivity through vents in the spent fuel pool building.

About 90 minutes later, the episode escalated to a "site emergency," when a second, unrelated accident occurred in Unit 3. A tube ruptured in the steam generator, leading to the release of radioactive steam through a safety valve that then became stuck in the open position. As crews in the plant began damage and repair assessments, Unit 3 was shut down and Millstone crews began taking measurements of radioactivity levels around the plant and at locations in the surrounding towns. Ultimately, a "general emergency" — the highest level — was declared as off-site radiation levels rose.

"The scenario was developed by Millstone... ," said Paul Blasioli, Dominion's director of nuclear protection services and emergency preparedness. "It has to be a new scenario. You have to test yourself in a way you haven't been tested before."

Editor's note: This version corrects Blasioli's title.

Once the assessment of the drill is complete, the scenario will be adopted as the basis of a training exercise for Millstone staff, he added.

At 11 a.m., the governor declared the general emergency. State parks and forests were closed, farmers were ordered to shelter livestock and feed them only covered food and water, and plans were being made to move schoolchildren in Waterford, East Lyme, New London, Old Lyme and part of Lyme to evacuation centers. A general evacuation of the area within a 5-mile radius of the plant was ordered.

The governor's office also ordered the distribution and ingestion of potassium iodide pills by the public to protect people's thyroids from absorbing radioactive iodine that can be inhaled from radioactive releases.

"But people should keep in mind this is not a magic pill," Burdick said. Potassium iodide, he noted, only protects the thyroid from harmful radiation, not other areas of the body vulnerable to exposure.

Burdick said the exercise was particularly useful for New London because the city has a new mayor, deputy police chief and deputy fire chief who have not participated in this type of drill before. In addition, he said, it gave New London a chance to try out its new emergency operations center, which has been relocated to a room in fire department headquarters on Bank Street. It previously had been in the police station.

Scott DeVico, spokesman for the state Department of Emergency Services and Public Protection, said that while no major problems were revealed, the exercise was good practice.

"Initial reviews are that it was a successful drill," he said. "It also helps with other types of emergency planning, for things like hurricanes and prolonged power outages."

j.benson@theday.com