UNDER STALIN, the Chernobyl nuclear accident in the Soviet Ukraine would have been accepted as the price of progress and the victims written off with a shrug. Indeed, building the dams and reservoirs of the Dnieper River, through which the wastes of Chernobyl may now flow on their way south to the Black Sea, cost more lives and hardship in Stalin's time than Chernobyl will now, even at its possible worst. But the Soviet Union has left those times behind.

Today's typical Soviet citizen is no longer a passive peasant but more and more a well-educated and sophisticated urbanite. Soviet leaders, alongside industrial progress, speak increasingly of public welfare. Soviet nuclear engineers would be sincerely indignant at the thought that they take the risks of nuclear power lightly or build shoddily; in some cases they have been more conservative than the Americans.

Take, for example, the Soviet choice of a graphite-core reactor at Chernobyl, a technology that Western experts now condemn as dangerous and passe. It was not so long ago that it was the Westinghouse pressurized-water design, with its single-unit reactor pressure vessel, that was considered the riskier technology. British experts warned that it might "peel like an onion" in case of trouble. The graphite-core reactor, in contrast, was based on a modular pressure-containment principle that raised no such threat. It had the further advantage of requiring less formidable fabricating techniques.

It is nevertheless a fact that the Soviet nuclear industry works in a radically different environment from its present-day American counterpart, and this colors its approach to safety. There is no strong watchdog agency standing over the Ministry of Power. Environmentalists cannot bring suit to stop construction, and Soviet newspapers, though they delight (especially lately) in exposes of official malfeasance, keep their targets modest.

If this recalls the United States of the early 1960s, when the Atomic Energy Commission was more concerned with promoting nuclear power than with regulating it and nuclear engineers promised an era of abundance in which electricity would be "too cheap to meter," the analogy is apt.

The Soviet Union still strikes the Western visitor as a country of technological optimists. They have just finished building a railroad through the rugged wilderness of eastern Siberia and have been talking quite seriously of diverting the equivalent of a large river overland from west Siberia into Central Asia. Most of the top Soviet leaders are engineers by training (even Gorbachev, who has one degree in law, took another by correspondence in agricultural science) and there is little challenge to the notion of "progress" as we defined it 30 years ago.

Unlike the United States, where no new nuclear plants have been ordered for a decade, the Soviet Union has the largest nuclear construction program in the world. Though nuclear plants generated only 11 percent of Soviet electricity last year (vs. 15.5 percent in the United States and 64.8 percent in France), its share is planned to grow to 19 percent in 1990 and to 30 to 40 percent by the year 2000.

Despite the Chernobyl disaster, it is highly unlikely that the Soviet leaders will change these plans, because nuclear power plays a crucial part in Soviet energy policy and there are no ready alternatives. In the USSR west of the Urals, where 80 percent of the population and industry are located, fossil energy sources are growing scarcer. Most Soviet oil, gas and coal now come from Siberia, but they are expensive to develop and transport. In addition, Soviet oil has become uncertain; output declined by 4 percent last year and the oil industry cannot count on stabilizing it by 1990, despite huge increases in investment. Soviet oil exports provide over half of Soviet hard currency revenue, which is essential for Gorbachev's plans for economic modernization. Whether nuclear power is actually the most efficient solution to the problem has been hotly debated among Soviet experts; advocates of Siberian coal, in particular, have criticized the commitment to nuclear. But the issues have been entirely economic, not environmental. Indeed, until last week most Soviet energy experts would have said that nuclear power is safer than coal.

Despite its high priority, the Soviet nuclear program has suffered chronic delays. By 1985 it was supposed to produce 220 billion kilowatt-hours, but it managed only 170. The lag stemmed principally from weaknesses in the Soviet machinebuilding sector, which was consistently starved for funds under Brezhnev, and in the notoriously weak Soviet construction industry. In addition, the Soviet press has routinely complained that skilled workers are in short supply.

The Soviet leadership responded to the delays by steadily increasing funding and pressure for faster results. But the combination of fast growth, political pressure and bottlenecks in construction and industrial support is a familiar formula for trouble in any country. Three years ago the Soviets suffered a major incident at a plant called Atommash, which manufactures nuclear reactors. They began production before construction was even half-complete, evidently skimping on geological studies of the area and neglecting the possible effects of seepage from a local reservoir. In the summer of 1983 some of the foundations gave way and a wing of the plant collapsed.

On the whole, safety standards in Soviet designs have not been as strict as in Western practice. Powerplants are frequently located near major population centers (notably at Voronezh, Gorky, Minsk, and Odessa), and the industry is beginning a new generation of nuclear heating stations that will be located inside cities. Only recently have the Soviets begun equipping some of their new plants with containment vessels. Ironically, Chernobyl-4, the site of the accident, and Chernobyl-3, which were commissioned in the early 1980s, had casing walls of reinforced concrete nearly three feet thick, while Chernobyl-1 and -2, uninvolved in the accident, had less elaborate safeguards.

Technological conservatism adds to safety problems by perpetuating older technologies. Why have the Soviets continued to build graphite-core reactors simultaneously with pressurized-water ones? The same peculiar Soviet reluctance to lay the old aside has also baffled Western students of Soviet military hardware. The explanation is partly bureaucratic: Behind every technology is a network of factories, research institutes and design loyalties.

Further complicating Soviet policy on safety is a military angle. The Soviet nuclear power industry, like its American counterpart, was born from technologies first developed for military purposes. Two civilian ministries build most of the equipment for nuclear power plants and another, the Ministry of Power and Electrification, assembles and operates them. But it is the ministry that makes nuclear weapons, an organization with the wonderfully euphemistic name of the "Ministry of Medium Machine-Building," that is in charge of fuel-cycle operations. This fact adds to the general secrecy with which safety questions are treated.

Nevertheless, there has been in recent years a slow but steady rise in the salience of the nuclear-safety issue inside the Soviet Union. As in so many other spheres of Soviet life, Western experience and practice seep into the country. The near-disaster at Three Mile Island was observed closely by Soviet engineers, and afterwards, containment vessels started to appear on new power plants. Foreign buyers were another influence on Soviet consciousness: When the Finns bought two Soviet powerplants in the 1970s, they insisted on Western safety features.

Many Westerners will be surprised to learn that there is a vocal environmentalist movement inside the Soviet Union, composed mainly of scientists but backed by strong popular sentiment tinged with nationalism. Though weakly organized, it has gained surprising coverage in the media and has scored some victories, notably against the pollution of Lake Baikal, hydropower construction in south Russia and the Ukraine and the dumping of untreated wastes in air and water. The Soviet government, which was totally indifferent to environmental concerns a generation ago, has mounted a modest environmental program. But the environmentalists' experience has been that, with rare exceptions, they make headway and gain publicity only when it suits the government's larger purposes.

A few years ago, the late physicist Petr Kapitsa stood up at a meeting of the USSR Academy of Sciences to warn of the environmental hazards of nuclear power. Later one of the founding fathers of Soviet nuclear engineering, Nikolai Dollezhal, criticized the practice of siting nuclear plants near major population centers. In 1983, in the wake of the Atommash scandal, Andropov created a State Committee for Nuclear Safety -- headed, revealingly enough, by an official drawn from the Ministry of Medium Machine-Building.

What will be the consequences of Chernobyl? We can be sure of one thing: The near-term commitment of the Soviet government to nuclear power will not waver. The remaining graphite-core reactors, reportedly shut down all over the country, will probably soon resume operation. The Soviets must displace oil, come what may, and nuclear is one of the few immediately available answers. Indeed, the recent collapse in world oil prices makes the problem more urgent than ever, since in order to maintain hard-currency revenues, the Soviets must export more than twice as much oil as before.

Eastern Europe may be another matter. The Soviet Union supplies nuclear powerplants, fuels and expertise to its East European allies, and nuclear power has been an important component of Soviet efforts to reinforce cooperation within the Bloc and to eliminate subsidized oil deliveries. The East Europeans initially welcomed nuclear power as a relief from their own energy problems (which are far more serious than those of the Soviets), but they may now take a cautious second look.

In the longer run, Chernobyl will strengthen the hand of Soviet critics who have been arguing that nuclear power is not as cheap as it looks. If heightened consciousness of safety problems leads the planners to take fuller account of the costs of containment, long-term storage, decommissioning and other matters that have become familiar fare in the West, nuclear power may begin to look less attractive to them than the newer coal technologies, such as slurry pipelines or "coal by wire" from mine-mouth plants in Siberia and Kazakhstan.

The emergency at Chernobyl has also exposed the weaknesses of Soviet civil-defense procedures, which seem to have been mostly paper plans. One of the repercussions of the accident will probably be the retirement of the chief of Soviet civil defense, Gen. Altunin, and a strengthening of the program.

Chernobyl is Mikhail Gorbachev's first major crisis as general secretary, and it is both a test and an opportunity. It is a test, first of all, of his proclaimed policy of public openness. So far, he has not exactly earned top grades, but if the unprecedented testimony of a Soviet embassy official on Thursday before a committee of Congress is any indication, we may yet see franker follow-up coverage. On the political level, Gorbachev will almost certainly pin the blame on local authorities and use the occasion to get rid of Ukrainian party boss Shcherbitskii, one of the few remaining holdovers of the Brezhnev era in the Politburo, and to gain control of the Ukrainian Party machine, which until now has eluded his grasp. Gorbachev will also use Chernobyl as an opening to shake up the power industry and to drive home two of his favorite policy themes, the need to improve quality control and to modernize the machinery and construction sectors.

Chernobyl is also Gorbachev's chance to show his people they now have a fully modern leader to lead their modern citizenry. By conducting a full public inquiry into the disaster, by taking elaborate measures to protect the population and submitting them to popular scrutiny, by tackling head on and in the open the dangers and risks of nuclear power, Gorbachev can do more than he could in a thousand Party Congress speeches to gain lasting public support for himself and his programs.

Chernobyl is unlikely by itself to shake the basic technological optimism of the Soviet establishment and people, or to bring fundamental changes to the Soviet approach to technological risks. But it is one more reminder of the frailty of the human animal in dealing with the products of its mind. Chernobyl is a lesson in humility for the Soviet Union, but also for the whole world.