Part of a morning newspaper's daily commitment to its readers is informing you of unusual events.

But some unusual events are more interesting than they are important. Take, for example, anything involving a pop music star.

And then there are the unusual events that involve nuclear power plants.

The phrase "unusual event," you see, is the specific designation given to some emergency situations that arise every once in a while at some of America's nuclear power plants. It is, as the name suggests, the lowest of the four government-delineated emergency classifications.

Here's how they're spelled out:

Unusual event -- The event poses no threat to the public or to plant employees, but emergency officials are notified. No action by the public is necessary. You can relax. The government and the power companies have everything under control.

Alert -- This is declared when an event has occurred that could reduce the plant's level of safety, but backup plant systems still work. Emergency agencies are notified and kept informed. No action by the public is necessary, beyond the obligatory raising of eyebrows.

Site Area Emergency -- OK, now we're talking. This is declared when major problems with the plant's safety systems may require the release of some radioactivity into the air or water. Still, the situation is not expected to exceed Environmental Protection Agency Protective Action Guidelines beyond the site boundary. No action by the public is necessary -- unless you're living in a trailer park in the shadow of the cooling towers.

General Emergency -- This means trouble. The most serious of the four classifications, it is declared when an event at the plant has caused a loss of safety systems. Radiation could be released that would travel beyond the site boundary. The alert and notification system will be sounded, and state and local authorities will take action to protect the residents living near the plant. People in the affected areas could be advised to evacuate. Promptly.

Yesterday, the PPL Corp.'s Susquehanna nuclear power plant in Berwick, about 250 miles east of us, had a situation. Or, more precisely, an "unusual event."

According to The Associated Press, a problem with the cooling system at the Luzerne County plant's Unit 2 prompted the declaration and, with it, the reduction of power output.

The trouble was an electrical failure in a panel and to the system that removes certain gases from the turbine's main condenser, without which the unit cannot operate at full power. But it was repaired quickly, the utility said.

The unit was back up to full power last night.

The event was reported at 1:25 p.m. and was declared at an end at 3:52 p.m. You were probably so busy at work you didn't even notice that the birds and the bugs stopped making noise.

(Just kidding.)