SEABROOK – An ammonium hydroxide spill forced the Seabrook nuclear power plant to declare an “unusual event” Wednesday afternoon, but officials said the incident was minor and didn't pose any risks to the public.

The spill, which involved less than a gallon of ammonium hydroxide, occurred around 1:45 p.m. in a stockroom where supplies are store inside an administration building, said Al Griffith, spokesman for NextEra Energy Seabrook Station.

The plant was required to declare an “unusual event” — the lowest of four emergency levels — because the building is located in a protected area.

Griffith said plant operations were not affected.