Nuclear power plants are full of signs warning people to be careful. "Beware of" signs are almost everywhere. But on a refrigerator?

Perhaps. On Wednesday someone removed a sandwich from a refrigerator at the Calvert Cliffs Nuclear Power Plant, a plant operated by the Baltimore Gas and Electric Co. What the thief didn't know was that the owner of the sandwich, victimized several times in the past, had set a trap by spraying insect repellent on this particular sandwich.

The repellent apparently was not toxic enough to do anything more than give someone a bad stomachache, but when the sandwich's owner found that his bait had been taken, he experienced remorse and reported what he had done to plant authorities.

A call went out over the public address system asking the thief to report to the medical office.

"We had no takers and no one has turned up sick," said BG&E spokesman John Metzger.

The guilt-ridden -- and perhaps hungry -- trap-setter, an employe of a private contracting company working in the plant's sewage treatment area, was led off the premises.

"I can almost sympathize with him," Metzger said. "He had lost his sandwich on a number of occasions. But we certainly couldn't condone what he did, even if he did confess."

Because the incident took place at a nuclear power plant, even though it was not near any of the vital plant areas, a preliminary incident report was filed with the Nuclear Regulatory Commission.

Carl Abraham, spokesman for the NRC's Region I office in Harrisburg, received a copy of the report. "I've dealt with a lot in this job, including Three Mile Island," he said. "But this takes the cake."

Or the sandwich.