BALTIMORE (AP) _ One of the first firefighters to respond to the blaze at the Soviet nuclear plant at Chernobyl said Thursday the crews didn't realize they were being exposed to potentially lethal radiation.

''At the hospital, the doctors gave us our first medication. We didn't think of death; we thought this would be a check-up,'' Soviet firefighter Lt. Col. Leonid Telyatnikov told the audience at a national firefighters' convention here.

Thirty-one people, mostly firefighters, have died since the accident in April 1986, the Soviet government has said. Six of the first 28 firefighters on the scene were among the casualties.

Telyatnikov said the firefighters responded to the blaze with just helmets, jackets and boots.

''I saw in front of me the remains of the damaged building of the fourth reactor. There was a glow - a bluish glow - above the building. There were flames of fire on other buildings. And it was absolutely silent.

''I was confused, and it was eery,'' the 36-year-old Telyatnikov said through an interpreter.

He said firefighters had no idea how much radiation they were exposed to - meters in the plant's control room were all ''stuck on maximum.''

Telyatnikov fought the fire for three hours before succumbing to radiation. He remained hospitalized for about a month with what Soviet doctors called second-degree radiation sickness, and didn't fully recover until after seven months, he said.

''Now I'm feeling fine, relatively,'' Telyatnikov said with a chuckle. ''I'm very lucky to be alive.''

Telyatnikov said he walked around the disaster site and saw debris from the initial explosion littered about, including pieces of radioactive graphite from the reactor building. Zirconium, used to protect fuel rods, burned like ''special lights on the Fourth of July,'' he said.

The fire burned for days before being contained by tons of sand dumped on it from the air.

Two of the six men Telyatnikov ordered to the top of an adjacent reactor collapsed from radiation exposure. They later died.

Telyatnikov attended the Great American Firehouse Exposition Muster '87, sponsored by Firehouse magazine, with Igor Kimstach, deputy chief of the 200,000-member fire service, a branch of the Soviet military.

Maryland State Fire Marshal Rocco J. Gabriele said Telyatnikov's visit emphasized the problems firefighters face with hazardous materials. ''Hazardous materials are a serious problem (for firefighters),'' he said. ''They're not going to go away.''