HEARING about the Navy jet with a nuclear bomb that rolled off an aircraft carrier 24 years ago near Japan, one is tempted to say, ``So what?'' It couldn't possibly blow up, and Japanese officials are only pretending to be surprised at the knowledge that US warships routinely carry such weapons in and around their territory. Everybody knows nuclear strike aircraft at sea have been part of the US war-fighting plan for decades. That's why Moscow is so eager for arms-controlling them out of existence.
But the point is not that one A-4 Skyhawk with its one-megaton nuclear device and unfortunate aviator was lost at sea during a routine bomb-loading exercise in international waters. Or even that a substantial chunk of plutonium - the most poisonous substance there is - is rolling around the seabed 80 miles off an inhabited island in the Ryukyu chain.
The point is, there have been far too many accidents at sea involving nuclear weapons and nuclear reactors, and the radioactive litter that results should be of greater concern to governments and international agencies.
There are upwards of 400 nuclear-powered ships and submarines worldwide today, powered by more than 550 reactors. Oceans being hazardous places, there have been about 60 incidents involving such vessels since navies went nuclear after World War II.
The USS Thresher and USS Scorpion, both nuclear submarines, were lost in the 1960s. But in general, the safety record for the US Navy's nuclear power propulsion program is quite good.
The Soviet record is not so good. Moscow says little about such things, but most of the nuclear accidents at sea over the years (including at least one reactor meltdown) involved Soviet ships and subs. In 1986, a Yankee-class submarine with 32 nuclear missile warheads and two reactors went down. And just last month, a Mike-class sub with two reactors (and possibly nuclear-armed torpedoes) was lost as well.
Like space, the oceans have traditionally been viewed as so vast that a bit of man-made junk doesn't matter. But astronauts and cosmonauts do have to worry about space junk, including nuclear reactors. And the same should certainly be true of the sea. Countries have curtailed their dumping of low-level radioactive waste. The US Navy ran into flak some years ago over its plans to scuttle decommissioned nuclear subs.
The US and the USSR have just agreed to a new cooperative effort on oil spills. They should do the same for the greater potential threat posed by the increasing use of nuclear power at sea.