During a recent full-scale emergency planning exercise at Seabrook Station, the power plant's personnel failed to recognize that the scenario involved an airborne release of radiation from the site, an oversight of “low to moderate safety significance,’’ according to preliminary findings released Tuesday by the Nuclear Regulatory Commission.

The most recent emergency exercise at the Seabrook, N.H., power plant, which is operated by Next­Era Energy Resources, was conducted on April 17. During the drill, plant personnel did not identify the radiation release scenario and consequently neglected to communicate information about the release to off-site authorities. According to the NRC report, this represents “a performance deficiency that was reasonably within NextEra's ability to foresee and prevent.’’

“Timely sharing of information with off-site emergency responders would be essential in the event of an actual plant emergency,’’ said NRC spokesman Neil Sheehan.

The agency will determine within 90 days whether the incident should be finalized as a “white’’ inspection finding, which connotes low-to-moderate safety significance, he said. The finding would result in the Seabrook plant receiving additional NRC inspections, Sheehan said.

NextEra is reviewing the preliminary finding and has not yet decided whether to contest it, according to plant spokesman Alan Griffith, who acknowledged that the reported lapse during the drill fell short of the plant's high standards in emergency planning.

“While a real-life event at Seabrook is highly unlikely, we conduct regular drills in order to identify issues and areas where we can further enhance our emergency planning processes,’’ he said. “We take this finding and all feedback from the NRC very seriously, and have already taken a number of steps to ensure this does not happen again.’’

The preliminary finding comes at a sensitive time for the plant, which has applied to the NRC for a 20-year extension of its 40-year operating license. The license is set to expire in 2030.

Several elected officials have sent letters of concern to the NRC, urging the agency to ensure that safety conditions at Seabrook have been addressed before rendering a decision on the plant's application for a license renewal. The public outcry was prompted by the discovery of degraded concrete in a safety-related electric control tunnel.