IN the frantic and free-wheeling economy of the post-communist Soviet Union, the melody of the moment seems to be "Anything Goes." Chetek, a new private venture linked to the central government's nuclear ministry, is now offering "peaceful nuclear explosions," in your country or mine, as an effective means of disposing of highly toxic wastes or stimulating gas and oil production. While at first glance the proposition appears almost laughable, it is said to be technically feasible, even economical. But its political and strategic implications are profoundly troubling. Chetek's entrepreneurial venture is just the most visible and "legitimate" manifestation of a rapidly burgeoning trade in nuclear goods and services now beginning to leak out of the disintegrating Soviet military machine like radiation from a ruptured reactor. Ironically, nuclear technologies and expertise represent one of the few markets in which the Soviet Union possesses a highly exportable, world-class product, one much in demand by those in a position to pay - and pay well - in precious hard currenc y. In an economy in desperate disarray, the incentives to sell - no questions asked, to whomever and for whatever purpose - are overwhelming. The disincentives, in the form of agencies monitoring and constraining the trade and alternative employment for idled nuclear workers, are virtually nonexistent. "Have bomb, will travel," Christopher Paine of the Natural Resources Defense Council calls it. But in actuality, the peril arises less from the possibility that ready-made nuclear devices will be marketed (though that is certainly a danger as tactical nuclear weapons are taken out of service) than that nuclear materials, technologies, and expertise will find their way into the many wrong hands now desperately seeking them to advance their personal or national ambitions. The challenge is exacerbated by the ambiguity of boundaries between military and civilian nuclear activities, since the export of many of these materials can be camouflaged as peaceful and legitimate commerce. Vital technological components, key hardware in the construction of nuclear weapons, could also be pilfered by disgruntled workers from existing stocks and surreptitiously sold to eager buyers. But most menacing, because it is least visible and most innocuous in appearance, is the probable proliferation of nuclear knowledge and expertise heretofore confined to highly secret government laboratories. This is not a case of a single genie being released from the bottle, but of thousands. As the START Treaty and unilateral arms reductions cut deeply into the Soviet military, thousands of highly trained military and civilian nuclear scientists are being laid off, along with thousands more technical s taff and military personnel who have maintained the arsenal. Many retain long-standing personal contacts with counterparts in countries whose civilian and military nuclear programs the Soviet Union assisted during the cold war. "Nuclear mercenaries," William C. Potter calls them. A nonproliferation specialist at the Monterey Institute of International Studies, he warns that in addition to seeking private profit, some disgruntled nuclear workers may see themselves as aiding their religious or ideological allies. Testing grounds and major facilities for producing vital weapons materials are located in Central Asian republics with close historical and ethnic ties to the Middle East. Working relationships have already been forged b etween Soviet Muslim scientists and their counterparts in Libya, Iraq, and Syria. Without impugning the integrity of any of these individuals, it is perfectly understandable that in the desperate circumstances in which many find themselves, the temptation to share their knowledge for a price could become irresistible. In short, we face a new Chernobyl, whose effects will be felt far beyond the toxic cloud spewed forth by that disaster. Now that the rupture has occurred, what can be done to stem the flow? Nonproliferation specialists see few quick remedies - indeed, few answers at all. "At this point, it would be an advance just to admit the scale of the problem," says Gary Milhollin of the Wisconsin Project on Nuclear Arms Control. Current international safeguards are pathetically inadequate. The International Atomic Energy Agency (IAEA), established under the Non-Proliferation Treaty as the only global nuclear monitoring body, has proven to be a half-blind cop, overlooking obvious traces of malfeasance in Iraq's nascent bomb program. But the problem goes deeper than the surreptitious activities of a few rogue outsiders seeking entry into the nuclear club. One of the chief reasons why IAEA safeguards are so lax is because none of the declared nuclear nations is willing to accept more rigorous scrutiny of its own activities. Current IAEA monitoring standards authorize its infrequent inspections only at sites officially designated by the host country, an arrangement that allows nations to undertake illicit activities anywhere else witho ut fear of being found out. Hans Blix, the IAEA's director general, has called for more frequent and intrusive inspections, as well as surprise visits. But the agency's board of governors, influenced by in- dustrial nations reluctant to send a message that would undermine public confidence in nuclear energy, recently deferred action on these proposals. In magnitude and significance, the disintegration of the Soviet nuclear empire dwarfs all other proliferation perils. Yet so few feasible remedies appear that nonproliferation specialists find themselves making suggestions that sound almost absurd. Some propose bringing unemployed Soviet nuclear scientists to the West to work and study - except that we already have a surplus of our own. Others suggest buying strategic raw materials (enriched uranium and plutonium) or even entire Soviet missiles, taking t hem off the market, then dismantling them and recycling wherever possible for civilian uses. But we can't even figure out where to put our own nuclear wastes. This predicament forces on the world community a task that it has long avoided - to establish a rigorous and comprehensive system to track the global movements of nuclear materials, technologies, and (to the limited degree possible) expertise. It is clearly neither equitable nor adequate to force such scrutiny solely on a few "prime suspects" like the Iraqis or Soviets, when there is strong evidence that nearly everyone else is also implicated in this highly lucrative trade. Soviet republics are likely t o bristle at such special treatment, especially if they come to see a value in retaining their nuclear apparatus as power cards in negotiations with other republics. Only when they see the same standard being applied to all other nuclear powers will they be willing to forego the strategic advantages that still accrue to those with a piece of the action. The ironies are extreme. The end of the superpower nuclear arms race has generated a new and more diffuse nuclear threat, supplanting a singular and unthinkable Armageddon with many smaller but more imaginable conflicts. Newly converted to capitalism, the former Soviet Union's most attractive export turns out to be nuclear technology and expertise. The crisis of the Soviet economy becomes a crisis of security for the entire world community, creating a class of nuclear refugees burdened with lethal knowle dge. The societies that created this knowledge must now cooperate as never before to assure that it is not misused.