In Hollywood the story might have been advertised as ''The Mystery of the Broken Seals.'' It was kept secret at the time. It has never been fully explained.
Now published for the first time, it turns out to have had a ''happy ending'' - but it also raises urgent questions about methods used to prevent what many diplomats, scientists, officials, and ordinary citizens see as one of the world's pressing problems: keeping nuclear weapons from spreading into unstable, dangerous countries.
In late December 1978, a US government inspector began routinely examining four metal containers at Kennedy Airport in New York. The four carried a total of five kilograms (11 pounds) of highly enriched uranium fabricated into fuel rods in California and in transit to a nuclear reactor in Bucharest, Romania.
The government seal on each container had broken.
The inspector could have stopped the shipment, opened the containers, and checked to see if any of the bomb-grade uranium fuel had been stolen or tampered with. But he did not. Other locks and fastenings appeared secure, so he simply attached new seals and sent the containers along.
Five days later, an inspector from the International Atomic Energy Agency in Vienna examined the containers in Bucharest. The new seals were intact. Nothing inside was missing.
Alarm signals rang on Capitol Hill when word of the episode leaked out in early 1979. Had the New York inspector failed in his duties? If someone had tried to steal the uranium between California and New York, it would have gone undetected for five days later: too late.
The Nuclear Regulatory Commission defended its man. It claimed the seals had broken in flight, accidentally. Eventually Congress let the issue drop.
But there are still questions. Among them: Are the precautions taken to prevent the theft or diversion of nuclear materials good enough? The IAEA is testing a new, US-developed system using automatic sensors to store and relay data to Vienna.
The superpowers could do much to help stop the spread of nuclear weapons. They could sign a comprehensive test ban treaty and limit strategic nuclear weapons. But prospects still seem distant.
Solutions suggested so far include:
* Stopping the exports of reactor, enrichment plant, and plutonium reprocessing components, plus enriched uranium and plutonium fuel (the approach favored by former President Jimmy Carter).
* Trying to strengthen the Vienna agency by providing more money and training for inspectors, upgrading surveillance cameras, counting fuel-rod loadings automatically, and increasing the number of inspections.
* Supplying economic and military aid to try to ease the fears of insecure countries.
* Creating regional nuclear-free zones.
* Making individuals more aware and concerned.
The right answer seems to be a combination of all these. Where experts differ is on deciding which methods to emphasize.
The need for intensified prevention methods is urgent. Nations like Pakistan, South Africa, Israel, and India reject pressure aimed at restricting their own freedom of choice, and regional hatreds and rivalries run deep. Knowledge about nuclear explosives is more freely available than ever.
Even an unknown free-lance writer named Howard Morland was able, after six months' research, to write an article in 1979 for a Wisconsin magazine called the Progressive entitled: ''The H-bomb secret - how we got it, why we're telling it.''
Imagine the resources a state like Pakistan has.
''Pay a visit to the library at the IAEA in Vienna,'' a US scientist advises. ''Look up 'Weapons, nuclear' and just see what is available. You can't recall that knowledge. It exists.''
The world is entering the era of the fast-breeder reactor, whose plutonium production exceeds its fuel consumption.
President Carter tried to stop the US and its allies from building them. President Reagan is attempting to reverse that process, while keeping safeguards. He has ordered work to resume at the Clinch River breeder reactor in Tennessee.
Paul Leventhal, former staff director of the Senate Nuclear Regulation Subcommittee in Washington and now director and founder of an antiproliferation group called the Nuclear Club, whipped out a pocket calculator.
''Safeguard inspectors agree,'' he said, ''that 1 to 1.5 percent of all plutonium or highly enriched uranium is a normal operating loss. They start worrying only when they find more than that amount missing in some way.''
A regular reprocessing plant can process about 1,500 tons of spent fuel rods from reactors. That's 3.3 million pounds.''
That contains 1 percent, let's say, of plutonium - 33,000 pounds. After it has been extracted, inspectors allow, let's say, 1 percent for so-called normal losses. That's 330 pounds.
''So anything less than 330 pounds of plutonium from this reactor is considered 'normal.'''
But, assuming about 16 pounds of plutonium is enough to make a plutonium bomb (the figure is actually smaller), that's 20 warheads and a half - nuclear warheads.''
At the moment, commercial-scale reprocessing plants are few and far between. There's one at La Hague, in France, and a pilot plant at Tokai Mura in Japan. India has a plant.
The Reagan administration has decided to try to undo President Carter's 1977 ban on reprocessing plants. Nothing will happen soon: The three US plants (West Valley, N.Y.; Morris, Illinois; and Barnwell, S.C.) are inoperative. But on Oct. 8, 1981, Reagan officials announced sweeping new plans that included lifting Mr. Carter's ban on these plants.
Soon, says Mr. Leventhal, ''There'll be more plutonium than ever before being transported from plant to plant.
''It's just a matter of time before you have diversions, or outright theft, or nuclear terrorism in our cities.''
How effective - and important - is the web of inspections and safeguards under the direction of the IAEA?
This newspaper's probe indicates they are essential - but that they should not be overrated or oversold. They have a role - to detect possible diversions of nuclear material. The IAEA is not a policeman - or a prosecutor.
All the IAEA has is a whistle. At first it blows the whistle softly, to its own members. If it detects diversion of plutonium, the director general can name the country to the IAEA board. Ultimately he can give a piercing blast and inform the United Nations Security Council.
After that, it's a political matter for the rest of the world.
In fact, the agency has never named anyone, either to its own board of governors, or to the Security Council.
Former inspector Roger Richter resigned from the agency to testify on Capitol Hill June 19 that agency safeguards were ''totally incapable'' of detecting whether plutonium was being illicitly produced in a large test reactor.
Countries, he said, could exclude key plants from inspection by saying they were not being used. The Osirak reactor in Iraq, he said, could have secretly produced 17 to 24 kilograms of plutonium a year. Inspectors visited only three times a year. No cameras had been installed.
IAEA safeguards chief Dr. Hans Gruemm visited the US to argue his rebuttal: His inspectors would have seen any attempt to siphon off nuclear materials from Osirak. Surveillance cameras and inspections would have been routinely heightened once a critical mass of highly enriched uranium had been delivered - it hadn't been when Israel attacked.
In fact, Dr. Gruemm has only about 140 inspectors, from various countries, and a safeguards budget of $25 million a year - less than the cost of a single F-16 jet.
To him, that reflects the state of the world - the wishes of IAEA member states, not the wishes of the IAEA. He believes the ratio of his safeguards budget to world spending on arms is 1:20,000.
Overworked and weary, his inspectors fly off to reactors and spent fuel ponds and reprocessing plants around the world, checking the records kept by member states, taking gamma-ray readings, peering through the bluish hue of water surrounding reactor cores or spent fuel ponds, changing film in automatic movie surveillance cameras, checking metal seals of stored nuclear material and camera cases.
Former inspector Emanuel Morgan, an American, has just told the US Nuclear Regulatory Commission that many inspectors don't speak the languages of countries they visit.
It's easy to poke fun at the inspectors: They have too much to do, too little time. They can't drop in unannounced: They have to apply for visas, like everyone else. Pakistan and other countries keep local officials with the inspectors at all times. Any country can reject an inspector because of his nationality - ''which means many of our Soviet inspectors sit around Vienna a lot with nothing to do,'' an IAEA source said.
(Iraq allowed only Soviets and Hungarians to visit Osirak, raising Israeli suspicions to even higher pitch.)
But the ''fault'' lies, not only with the inspectors (who can, over a period, build up a pattern of surveillance by checking and cross-checking records, just as an internal revenue service cross-checks tax returns), but mainly with a world where states remain jealous of the last ounce of sovereignty.
Since 1968, 111 nonnuclear countries, plus the US, the Soviet Union, and Britain, have signed the Nonproliferation Treaty, or NPT.
Nuclear states keep their bombs but agree to negotiate ''in good faith'' to reduce them. Nonnuclear states accept international inspection, in return for freedom to keep using nuclear power for peaceful purposes.
They are also guaranteed a flow of technical assistance to help them develop nuclear programs.
But nonnuclear states are becoming more and more restive. Superpower arsenals are growing all the time. SALT II is in limbo. Nuclear countries sell technology at commercial rates: They don't give it away.
These smaller states are not impressed with new US-Soviet talks on reducing forces in Europe. They tend to be cynical about President Reagan's ''zero option'' plan for eliminating all missiles in Europe if the Soviets agree.
They were upset when former President Carter persuaded Congress to pass the 1978 Nuclear Nonproliferation Act, because its effect was to deny fuel and technology to any country unwilling to accept full-scope safeguards. To them, this showed the US owning massive nuclear arms and determined not to share nuclear know-how.
''If we tried to negotiate the NPT today, we couldn't,'' one expert in Vienna says.
Major nonsigners of the NPT: France and China, Pakistan and India, Israel and South Africa, Argentina, Brazil, Chile, and Cuba.
France remains controversial. It says it behaves as though it had signed the NPT. But, in fact, scientists and officials in the US and Britain, and even some in France itself blame Paris for selling two of the most controversial reactors in the world today. One went to Dimona in Israel's Negev Desert in 1963. It has been used to create plutonium ever since. The other was Osirak.
France also agreed to sell Pakistan a large reprocessing plant in the mid- 1970s. It backed away from the deal only under US and European pressure. But blueprints had already been delivered. Pakistan, sources say, copied them and used them to build a smaller reprocessor - an essential part of the cycle needed to make nuclear bombs from plutonium.
A spokesman for the Atomic Energy Commission in Paris says that France had agreed to rebuild Osirak. But talks about the site, the type of reactor, the fuel, and safeguards could take up to a year. Privately, French officials acknowledge heavy world pressure to tighten safeguards and to substitute ''caramel'' fuel, which is harder to use in a bomb.
Nonetheless, the system has its uses. A state like Pakistan, which refuses the degree of inspection Vienna officials want, is automatically spotlighted.
No state has yet given the requisite three-month notice to withdraw. To do so would be to confess openly it intended to build a bomb.
The IAEA does not work in a vacuum. It is just one part in a wider system that includes (1) military intelligence from the US, Israel, India, and other states; (2) the knowledge that spreads like wildfire on the unofficial ''gossip'' network of nuclear scientists around the world; (3) pressure by the superpowers on states like Pakistan (and West Germany, which Moscow watches like a hawk).
The US will not sell any nuclear material to a country that does not subscribe to NPT full-scope safeguards. Many other countries demand IAEA inspection only on material they themselves provide.
On a desktop in Vienna sits a white metal box. Once a week it flashes an automatic signal to seven black boxes sitting on other desktops around the world.
One black box is at a nuclear storage site at Lucas Heights, Australia; others are at a reactor outside Sofia, Bulgaria; in Manitoba, Canada; outside Cologne, West Germany; north of Tokyo near the city of Mito; at a research reactor in Cambridge, Mass.; in the rolling countryside of Harwell, outside Oxford, England.
When the tamper-proof black boxes receive the command signal, they release coded information they have already retrieved and stored from tiny automatic sensors. The sensors are on automatic surveillance cameras in sealed metal boxes, at the entrances or exits of nuclear reactors, and on stockpiled nuclear material.
Within three minutes, all the boxes have released their stored data and zipped it back across thousands of miles to the master white box in Vienna.
Now the white box knows whether film in the cameras in Australia, Bulgaria, Canada, West Germany, Japan, the US, and England has been broken . . . if the video system is working . . . if the power is still turned on inside the cameras . . . whether sealed boxes or sensors have been tampered with.
This is dizzying technology. It has been developed by the American firm, TRW, in answer to a US idea to peer more efficiently and more often into countries' nuclear sites.
But it is also a problem.
So far, it is only a pilot plan - Operation RECOVER (for Remote Continual Verification). It has cost $3.5 million. Failures and random signals have occurred at a rate of a mere 0.5 percent, US officials on the program report.
It is real Buck Rogers material - except that the system might work too well.
The USSR won't accept it (as a nuclear weapons state, it doesn't have to). Other states could also reject it as too intrusive.
Already poorer countries on the board of governors of the IAEA are raising a host of questions - what will it cost? Who pays for installing the black boxes and the sensors? How often can Vienna call up stored data? How many sensors should be affixed to how many reactor sites? What control will each country retain? (Inspectors have to be issued visas - but an electronic signal is a different matter.)
Detractors say, ''Too much machinery, too much reliance on wires and circuits , too much danger of false signals and equipment failure. . . .''
A similar system is being developed to cover nuclear materials - plutonium, enriched uranium - in transit. It is called Operation TRANSEAVER.
Japan prefers instruments to inspectors at Tokai Mura because the plant could keep working while sensors operated. Australia is interested in TRANSEAVER as a way of safeguarding long sea voyages.
But many other countries may reject the new gadgetry. There's such a thing as a too-super supersleuth.
One solution to spreading weapons is the setting up of regional nuclear-free zones. So far, however, progress is slow.
There is one nuclear-free zone: Latin America. In 1967 a number of nations there signed a treaty with an almost unpronounceable name: Tlatelolco, named after the place in Mexico where it was drafted.
Today, 14 years later, Cuba, Chile, Guyana, and the two hemisphere giants, Argentina and Brazil, still have not accepted the treaty.
Twenty-two states in the area have signed, plus the US.
The five nuclear-club members in the world (US, Soviet Union, France, Britain , and China) have agreed not to introduce nuclear weapons into the zone. The US, Britain, and the Netherlands have agreed not to station nuclear weapons on their Latin American territories.
France has a constitutional problem. Since all French departements are equal, France could not forswear nuclear weapons in Martinique without doing so in Marseille.
Much depends, of course, on Argentina, Chile, and Brazil. Why haven't they accepted the treaty?
The answer lies in a mixture of regional rivalries, insecurities, and ambitions.
Chile and Brazil say everyone else must ratify first. Translation: They won't sign before their rival, Argentina.
In fact, Chile and Brazil have signed, and ratified - but they have not waived a provision that says the treaty takes effect only when everyone has signed. The 21 other states have waived this provision and accepted the treaty for themselves and all other signers already.
What about Argentina?
It has signed - but not ratified. It has offered a variety of reasons over the years. The latest: It has to negotiate safeguards with the IAEA first. (Other states have ratified first, then talked about safeguards.)
Adm. Castro Madero, head of Argentina's Atomic Energy Commission, puts his view of the IAEA in a nutshell: He tells newsmen that every country ''has the right to develop the technologies it needs.'' Buenos Aires refuses to give up its right to peaceful nuclear explosions.
Partial translation: Brazil must agree first, please.
The US ''continues to be hopeful'' that Argentina will accept Tlatelolco. Translation: Don't hold your breath.
All those who don't accept the treaty worry about the possibility of Soviet nuclear warheads in Cuba. Cuba might come under heavy pressure from Moscow to sign if everyone else does so first. Without that, Moscow won't insist.
Argentina is moving steadily toward an independent fuel cycle. It leads the field in Latin America.
Experts say its power reactor Atucha 1 has produced 200 kilograms of plutonium since January 1974 - still in spent fuel rods and safeguarded by the IAEA under a three-way agreement with Vienna and West Germany, which provided the reactor.
Argentina is ambitious. It has plans to spend $5 billion to $7 billion in this decade alone. Its scientists are well-trained.Canada has built a second reactor. West Germany is working on a third.
Canada insists on safeguards, and would have demanded even stricter ones had it landed the contract for the one it lost to Bonn. Bonn is asking safeguards only on the reactor it is building - not full-scope safeguards on everything in Argentina.
Switzerland is building a heavy-water plant (also asking for safeguards only on its own plant). Argentina is working toward making its own fuel rods and building a small reprocessing plant.
Ambitious, wealthy, determined, it is a country to watch.
Brazil entered the field much later, and less efficiently.
Almost all its nuclear eggs are in one West German basket: a gigantic agreement signed in 1975 for a total of nine reactors, a reprocessing plant, and two enrichment plants.
Bonn has also agreed to build a plant to make fuel rods.
The US and others have made clear to Bonn that they have grave doubts about this huge scheme.
In fact, Brazilian uranium is to be enriched at the URENCO plant in the Netherlands, run by Holland, West Germany, and Great Britain. The Dutch are adamant they will not agree unless ultra-strict safeguards are clamped on.
Nonetheless, if the deal goes through, the Brazilians will have considerable knowledge by 1990. The more it has, the more Argentina will worry - and the less likely it may be that Tlatelolco will be fully accepted.
But there is a bright side to the story. ''Yes,'' said Jeremy Stone, director of the Federation of American Scientists in Washington, in an interview. ''Yes, the dike could be breached. Weapons could spread.''
But so far the process of proliferation hasn't happened automatically or quickly. It's been slower than people thought, and that gives hope that it can be further restrained and even halted.
''The whole name of the game is to buy time, until the security problems of the world - the Mideast, South Korea, Taiwan, and others - might be eased. . . .''
The superpower arms race has gone worse than anyone had expected.
''Proliferation has gone far better.''
The list of states that could take a quick step across the nuclear threshold is limited - though experts agree that by 1990 it will have two dozen or so names.
Experts like Jeremy Stone say you have to deal with these states on an individual basis, rather than looking for some kind of global, overall strategy.
Three of the many ideas offered to this correspondent:
Israeli scientist and member of parliament Dr. Yuval Neman: ''No country should sell highly enriched uranium to another. It should lease it, guard it, inspect it on site, and repossess fuel rods containing plutonium.''
Paul Leventhal of the Nuclear Club Inc.: ''Ban the use of highly enriched uranium and plutonium in commercial reactors.Use only natural or low-enriched uranium. Lock up all spent fuel rods, which contain plutonium, in some kind of international storage.'' (Talks on such a storage system have bogged down.)
US defense consultant and research professor Edward Luttwak: ''Concentrate on the countries trying to get the bomb. Collect intelligence. Put pressure and publicity onto the big companies that sell nuclear components. Other governments might resent US pressure; the people of the world would welcome it. Don't use armed force - unless Libya starts to get nuclear weapons. In that one case, you would have to strike.''
The last word, perhaps, should come from a man who was close to having the first: Bertrand Goldschmidt of France, the grand old man of safeguards and nonproliferation, author of the book ''Le Complexe Atomique.''
Small, wiry, neat, precise, he worries as much these days about the nuclear stockpiles possessed by weapons states as he does about other countries or terrorists or Libya getting a bomb.
''The 11,000 tactical nuclear warheads stored in West and East Germany could be stolen,'' he told me in Vienna.
He paused, thinking back as well as forward.
''Don't forget the positive aspects,'' he reminded me. ''There have been three miracles.''
Miracle No. 1: ''August Lindt of Switzerland and I struck the compromise that allowed the IAEA to be born in October 1956,'' he recalled. ''States were allowed to keep fissionable materials they needed for research or in existing reactors or those being built - before then, the idea was that states had to yield their stocks to an international body. France and India and others saw that as exploitation. After all, in those days, the US controlled most of the world's uranium, along with Britain.
''Safeguards were accepted - a political revolution!
''For the first time countries gave up some sovereignty to get the nuclear materials they wanted - unprecedented.''
The USSR after 1963 supported the US on the need to stop other nonnuclear countries from getting the bomb.
Miracle No. 2:
In the first decade after World War II, three countries got the bomb: the US in 1945, the USSR in 1949, the United Kingdom in 1952.
In the second decade, two: France in 1960, China, 1964.
In the third decade, one: India, 1974.
In the fourth decade: none - if the flash in the sky on Sept. 22, 1979, between South Africa and Antarctica was not a bomb. No one seems to know.
''The fact is that no one has embarked on an open nuclear arms campaign since 1964,'' Mr. Goldschmidt said.
Miracle No. 3:
The five countries that could easily have built a bomb after the war did not.
West Germany, Japan, and Italy had to renounce nuclear weapons as part of settlement agreements after the war. Canada decided it was secure and didn't need a bomb. Sweden had a long struggle, but eventually went the same way.
Romania, Hungary, Finland, and Bulgaria also had to renounce nuclear arms after the war to obtain peace treaties.
But the ''pause'' in proliferation of recent years may be coming to :n end - unless much more is done.
What can YOU do to help halt the spread of nuclear weapons?
Experts, including Paul Leventhal, suggest:
Take an interest in the issue. Become involved.
Contact your representatives in Congress and ask what their views are. Let them know you support arms control.
Find out more about what the International Atomic Energy Agency is and what it does.
Look into nuclear power in your area. Whether or not you think nuclear energy is desirable, there are other issues:
How safe is your local reactor (if you have one) against sabotage and theft? What is happening to the spent fuel rods taken from the reactor every two years or so? Are they being held for reprocessing (to extract plutonium from them) or are they being kept in cooling ponds with the plutonium still locked up harmlessly inside?
''Proliferation is ultimately a home-town problem,'' Mr. Levanthal says. ''Stolen plutonium can be used anywhere, including Main Street.''
Mr. Leventhal's organization, the Nuclear Club Inc., is at 1742 ''N'' St., NW , Washington, DC 20036.