The Nuclear Regulatory Commission investigating two leaks of radioactive gasses -- described as posing no health hazard -- that occurred this week at the Baltimore Gas and Electric Co. nuclear power plant at Calvert Cliffs, 45 miles southeast of Washington.

An NRC spokesman said the gasses, mostly Xenon-133, escaped from one of the plant's reactors Monday and Tuesday.

Although workers were evacuated from an auxiliary building on both days, the radioactivity was described as "extremely low," and one NRC spokesman said radiation from a chest X-ray would be 30,000 times stronger than the maximum exposure from the leaks.

The leaks were discovered by an NRC resident inspector who regularly checks the nuclear plants' log books.

The agency's investigation will try to determine whether the plant properly evaluated the cause of the releases, if any violation of NRC regulations occurred and if the plant followed proper reporting procedures.

Calvert Cliffs' spokeswoman Rona Stokes said workers were exposed to only .008 millirems of radioactivity, an amount that she said, "according to our guidelines . . . is not reportable."

According to Stokes, it was the first time such leaks have occurred at the five-year-old plant, located in Lusby, Md., 70 miles south of Baltimore on the western shore of the Chesapeake Bay.

The first leak occurred at 5:15 p.m. Monday, the NRC said, when radiation alarms in Units 1 and 2 of the plant sounded. The release of the gases stopped 15 minutes later, the NRC said, and the evacuated workers returned to the building at 8 p.m. that night.

At 7:20 a.m. Tuesday, the alarm sounded again. Workers were evacuated but returned 10 minutes later.

NRC spokesman Karl Abraham said the first leak apparently occurred when water in which gases were dissolved under pressure seeped from a leaky valve and the gasses, no longer under pressure, escaped. The second leak, he said occurred because a vent valve was not closed. It may have been human error, he said, or "the valve wouldn't close all the way."

Although the release of radioactivity was "extremely low," said NRC spokeswoman Sue Gagner, any release "would not be routine."

The nuclear plants' two reactors are still in operation, the NRC said yesterday.

Calvert Cliffs is regarded by nuclear experts as a relatively "clean" facility. A 1976 NRC survey gave the plant a "B" grade for overall operation and safety on a scale of "A" to "C." Of the 25 "abnormal occurrences" reported to Congress since 1975, none has involved the Maryland plant.

Baltimore Gas and Electric is Maryland's largest power company, serving nearly 800,000 customers, mostly in the Baltimore area. Calvert Cliffs, with two reactors, is the state's only nuclear power plant.

Gov. Harry Hughes' office said the governor "has asked our environmental health people to make a full report and what steps were taken to correct it. . . .Right now it appears the situa- [TEXT OMITTED FROM SOURCE]