As of now, we have learned more about Mikhail Gorbachev than about the nuclear accident still unfolding in his country.

The expectation when he took office was that the general secretary was a "new" kind of Soviet leader, an open executive whose paramount interest was making things, that is communism, work. His criticism of drunkenness, sloth and inefficiency held promise of an era of common sense.

But the ghastly events of the past few days show that Gorbachev is as conventional and hidebound as his predecessors.

The Soviet inability to admit error, to publish bad news except about other countries, has been grossly, grotesquely, on view. The practice of concealing all domestic calamities without redeeming elements of socialist heroism has been carried to new depths in the case of the Chernobyl meltdown.

Indeed the Soviets might have made no mention of it had not they been forced to by an outcry from neighbors to whom an ill wind had brought frightening levels of radioactivity.

It was only in response to these outraged alarms that Soviet television broadcast a terse notice about the accident. Subsequently, admission was made of two deaths. Communication with Kiev, the major city near the nuclear site, has been cut off and Soviet officialdom continues to deny that an accident that could affect the lives of all Soviets and many Europeans is anything more than "a local accident" -- as a visiting Soviet bureaucrat termed it.

Only a call for outside help from Swedish and West German experts -- Soviets regard an SOS as a humiliation -- and a single reference on Moscow radio to the meltdown as "a disaster" -- suggest a realization of the dimensions of the tragedy.

At a moment when the Soviets could have had world sympathy and scientific solicitude, they have created a meltdown of their credibility and underlined the black secretiveness of their system and their callousness to human suffering.

Gorbachev has behaved like the most monolithic, unimaginative and brutal of commissars and has served notice that he cannot break out of the mold of paranoia, defensiveness and obliviousness to "a decent respect for the opinions of mankind."

His conduct has almost guaranteed that the catastrophe will produce no beneficent fallout -- except possibly to technocrats who knew already that graphite reactors are chancy and that it is unacceptable to have civilian power plants without a containment building to hold lethal emissions.

Any benefit to the cause of world peace that might have resulted in a steady flow of information disclosed in a timely manner is not likely. Those who wish to make a connection between the nuclear arms race and the shrouded suffering of the people of Chernobyl and Kiev must do it on their own.

If Gorbachev had invited the world to view the devastation at the plant and the victims -- they have belatedly begun to admit there were more than two -- he would have made the most powerful imaginable case for the nuclear test ban he has so vigorously espoused in other less-promising circumstances.

Real-life scenes reminiscent of "The Day After" could have done more than anything else to bring the world up short on the mad pileup of nuclear weapons (50,000 at last count) and brought home the incontrovertible fact that even the most benign nuclear use in power plants carries risks that deserve reexamination.

But that is not the Soviet way.

And the day, or days, after -- even the exact time of the meltdown is not divulged -- when the talk might have been about how to avert other such disasters, how to rein in the nuclear monster, Washington officials were smugly saying that "it can't happen here" and others were talking about a repulsive system that lies as it breathes -- and making sick jokes about the wonderful political fallout for Ronald Reagan, who, due to the potential contamination of the soil of the Soviet breadbasket, may solve his problem with failing U.S. farmers.

On Tuesday, in answer to sharp questions from Sen. Carl Levin (D-Mich.) at an Armed Services subcommittee hearing, those two militant enemies of arms accords, Richard N. Perle of the Defense Department and Kenneth L. Adelman of the so-called Arms Control and Disarmament Agency, were unreconstructedly reiterating their opposition to negotiations on a comprehensive test-ban treaty even if there were no verification problems.

Gorbachev had helped make it easier for them. He has shown himself, when it mattered most, not to be the "different" Kremlin boss of global hope.