Damaged Soviet sub leaking radioactivity?

A Soviet nuclear attack submarine that was immobilized after catching fire west of Okinawa Aug. 20 may have leaked radioactive material into the sea, according to the Japanese Foreign Ministry.

Japan has expressed "grave concern" over the incident in which nine crewmen were killed and three others injured aboard the Echo-1 class submarine.

An initial survey by Japanese aircraft has revealed no radioactivity in the air, officials say. But whether the sea has been contaminated or not remains to be seen. A vessel of the Japanese Maritime Safety Agency is steaming into the area to take water samples.

By sunset Aug. 20, 55 of the crewmen had been rescued by the Soviet merchant training vessel Meridian, according to the Japanese Self-Defense Forces.

The captain of the 4,600-ton submarine refused all offers of assistance after the fire, the cause of which is unknown. The Maritime Safety Agency said the submarine would not even identify itself to a nearby Russian warship beyond saying it was based in Vladivostok and carried 100 men.

Had the fire been truly devastating, and had the crew abandoned ship after the accident -- which occurred in international waters -- the submarine could have been a considerable intelligence prize for the West. In 1977, a defecting Soviet pilot flew a sophisticated MIG-25 "Foxbat" warplane to Japan. The plane was later dissected by US and Japanese intelligence experts.

Only five Echo-1 submarines were built, probably because they were prototypes for the Echo-2. The first boat was completed in 1962.

The Echo-2 boats were originally armed with six Shaddock cruise missiles. But 10 years ago they were converted to an attack role when their missile launchers were removed. They are thought to be equipped with 10 torpedo tubes and 36 mines. Officially, each boat carries a complement of 12 officers and 80 men.

The Russians have not forgotten that when they lost a Golf- 2 class submarine northwest of Hawaii in 1968, following an on-board explosion, the US later raised parts of it.

According to Defense Department spokesman Thomas Ross, the US is maintaining "the normal type of surveillance" of the crippled submarine, which is expected to be towed back to its base, damage permitting.