VERNON, Vt. — Almost 100 people have lost their jobs this month at the Vermont Yankee nuclear power plant, which will cut its staff to 150 full­time workers.

Entergy Nuclear spokesman Martin Cohn said 97 people will be laid off, effective May 5, to reflect the reduced staffing requirements prompted by the elimination of the emergency evacuation zone.

The layoffs were expected; the formal announcement was made Thursday.

Of the 97 people, 38 live in Vermont, 34 reside in New Hampshire and 25 live in Massachusetts.

Emergency planning for the 10­mile zone surrounding Vermont Yankee won’t be necessary, according to the Nuclear Regulatory Commission, once the spent radioactive fuel cools to a certain temperature.

The NRC has put that time at 15 months after being removed from the Yankee reactor core, when the potential for an accident and the release of radiation drops.

Last week’s announcement was a formal notification of “mass” layoffs, as required by the Vermont Department of Labor, Cohn said, although the layoffs had been expected for months.

He said employment at Vermont Yankee was at 625 in August 2013, when Entergy made the decision to shut down the plant in December 2014.

On Jan. 19, 2015, a few weeks after the shutdown, employment dropped to 316 people, he said.

The next drop in employment won’t come until 2020, when all the radiological fuel is transferred from Yankee’s spent-fuel pool to air-cooled concrete and steel casks, a system called dry cask storage.

After that transfer, there will be 57 Entergy employees, Cohn said.

In addition to the notice sent to the state, Entergy was required to send notices to the towns of Vernon and Brattleboro, since the company has offices and employees in both towns.