NUCLEAR PLANT IN RUSSIA LEAKS RADIOACTIVE GAS

MOSCOW, MARCH 24 -- MOSCOW, MARCH 24 -- A nuclear power plant outside St. Petersburg was shut down today after a leak of radiation, but Russian officials said the incident poses no significant threat to the environment or nearby population.

Russian authorities said radioactive iodine leaked early this morning from one of the four reactors at the Leningrad power plant, but that the only contamination risk was on the plant's premises. Monitoring stations in Austria, Sweden and Finland reported picking up no unusual amounts of radiation in their areas.

Yuri Rogozhin, a spokesman for the Russian nuclear energy inspection agency, said that while the incident was "serious," it was in no way comparable to the 1986 disaster at the Chernobyl nuclear plant -- which killed 31 people, forced the evacuation of thousands more and spewed radioactivity across Ukraine, Belarus and much of Europe -- or to the 1979 nuclear accident at Three Mile Island in Pennsylvania.

Despite the official reassurances, today's incident at the plant near Sosnovy Bor, 60 miles west of St. Petersburg -- formerly Leningrad -- on the Gulf of Finland, rang alarm bells across Europe, where worries of contamination from another Chernobyl run high.

A large number of aging nuclear power plants, many of questionable safety, are still in operation in Eastern Europe, especially in the former Soviet Union. Some nuclear experts have warned that a combination of design flaws, age and poor maintenance make another major disaster inevitable and have urged that many of these power plants be shut down.

"This accident is yet another example of how aging reactors are threatening the world," said John Willis, a nuclear power specialist with the Greenpeace environmental group.

Concerns are strongest over the reactors in the former Soviet Union, because of the chaotic atmosphere in which many things seem to be crumbling. A Russian newspaper recently reported cutbacks in operating personnel at some nuclear plants.

There are 45 nuclear reactors at 15 nuclear power plants in the territory of the former union; 16 of them, including those near St. Petersburg, are based on the Chernobyl model, according to the International Atomic Energy Agency in Vienna. These plants, which are built without any containment structures that protect against leaks, produce about half of the nuclear power in the former Soviet Union. Foreign experts have said that safety standards have improved somewhat since the Chernobyl disaster but are still well below international levels.

After hearing reports of Tuesday's leak, Germany's environment minister, Klaus Toepfer, called for an immediate shutdown of all Chernobyl-type reactors. "They must be switched off as soon as at all possible," he said at a news conference in Bonn. He said the West should provide aid to help countries in Eastern Europe and the former Soviet Union develop safer alternative sources of energy.

While there have been no major nuclear accidents in the ex-Soviet republics since Chernobyl, small incidents involving temporary shutdowns are reported with some frequency. Chernobyl, for instance, was shut down briefly in October because of a fire. And Leningrad was shut down momentarily last month after a drop in power to the plant triggered its emergency system.

At the same time, economic pressures have made the continuing use of the plants vital right now despite safety concerns. Chernobyl, which is north of Kiev in Ukraine, for instance, is scheduled to be shut down for good in 1993, but for now it continues to operate, with the reactor where the 1986 explosion occurred encased in cement. Armenia, left without heat or electricity because of an oil and coal blockade by neighboring Azerbaijan, may soon start up a reactor that was shut down for safety reasons after the December 1988 earthquake.

Just two months ago, the Leningrad plant was criticized by Swedish inspectors, who reported that its safety standards fell well below international levels. They said the facility lacked proper equipment to contain leaks in two of its four reactors. Russian nuclear energy officials reported last month that two nuclear power plants, including Leningrad, were no longer being operated at full capacity for safety reasons.

Greenpeace officials said the Leningrad plant had been under partial rehabilitation recently. One reactor already had been refitted -- a process that involves cleaning and strengthening the facility -- and the second reactor's refitting was now underway. The third reactor, where the radiation leaked early today, was scheduled to be shut down for rehabilitation soon, they said.

According to Russia's Itar-Tass news service, the incident began at 2:37 a.m. when radioactive iodine leaked into the reactor's machine room, causing radiation levels there to reach 10 times the normal level. The radioactivity then escaped into the atmosphere through the ventilation system, passing through cleansing filters first. Rogozhin, the spokesman for the regulatory agency, said the power plant's emergency system was triggered immediately and the facility then shut down.

According to Rogozhin, a team of investigators was sent from Moscow to conduct a thorough inspection of the reactor, which will take about three days to cool down completely. Rogozhin said officials are constantly monitoring radioactivity levels at the power plant to see if any further leakage is occurring.

He also said the incident was rated at level 3 on the IAEA's 7-point scale of nuclear accidents, meaning there had been no off-site contamination.

The Russian Atomic Energy Ministry later downgraded the incident to a 2; this, the IAEA said, "would indicate that no significant levels of radiation exposure or contamination have occurred." Chernobyl, the worst nuclear accident in history, was ranked at 7.

In St. Petersburg, meanwhile, city officials said they believed the radiation had been contained and there was no reason for panic. The chairman of the city council, Alexander Belyayev, said the third reactor would be stopped for about four days for repairs and that the city would receive energy supplies from elsewhere.

The Soviet Union has 15 nuclear plants with a total of 45 reactors. Both Chernobyl and Leningrad, site of yesterday's accident, are older designs considered unsafe due to a lack of containment. No reactors of this design are operating commercially outside the former USSR.

........... YESTERDAY'S ACCIDENT ...........

The Leningrad nuclear plant is of the same type as Chernobyl, site of world's worst nuclear accident.

Radioactive gases leak from Leningrad nuclear plant.

International Atomic Energy Agency accident scale

7. Major accident - Chernobyl (1986)

6. Serious accident

5. Accident with off-site risks

4. Accident mainly in installation

3. Serious incident

2. Incident - Leningrad nuclear plant

1. Anomaly

............... LOCATIONS AND TYPES OF REACTORS ..............

LENINGRAD

Yesterday:

A leak in the graphite tubing of reactor No. 3 emits a small amount of radioactive gas into the atmosphere.

IGNALINA

July 10, 1991:

Leak contaminates three people and parts of the facility.

KURSK

June 26, 1989:

During repairs, radioactive water spills. Some leaks out of the building.

BALAKOVO

March 4, 1992:

Fire forces shutdown. No radiation is reported released.

CHERNOBYL

April 26, 1986:

Explosion, fire spread a cloud of radiation. Government says 32 people were killed, but scientists and physicians claim the toll was at least 250 and possibly as high as 10,000.

Oct. 11 and Nov. 1, 1991:

Fires at plant. No radiation release reported.

SOURCES: U.S. Council for Energy Awareness, Associated Press

Articles appear as they were originally printed in The Washington Post and may not include subsequent corrections.