Russia's nuclear car-boot sale: 'Atomic fingerprints' should reveal how stolen plutonium ended up in a German garage. Andrew Higgins reports from Moscow

THE TRAIL begins in the garage of a travelling salesman down on his luck in Germany. It ends, or so suggest matching 'atomic fingerprints', inside Arzamas-16, the home of the Soviet Union's first atomic bomb and the hub of Russia's vast, crumbling nuclear archipelago.

When police raided the home of Adolf Jaekle in the small south German town of Tengen in mid-May, they were expecting to confront a counterfeiting ring. What they found was a cylindrical container made of lead. Its contents seemed harmless enough: shards of glass, brush bristle and metallic powder. Three months - and further finds - later, the world's spooks, scientists and diplomats can talk of little else.

It dominated the conversation last week when US Secretary of State Warren Christopher and other senior figures gathered in Brussels for the service in memory of the Nato secretary-general, Manfred Worner. And it pushed its way to the top of the agenda being planned for a summit meeting next month between Bill Clinton and Boris Yeltsin.

Russia's nuclear facilities were once so secret that the towns where they stood did not appear on maps. Now they are blinking in the glare of anxious international scrutiny. The West is having nightmares of a freewheeling nuclear bazaar. Russia, stung by allegations of nuclear incompetence, sees a plot to undermine its last claim to great power status.

The anxiety raised by the contents of Mr Jaekle's garage sharpened to feverish alarm on the discovery two weeks ago of a lead-lined suitcase holding 300 grammes of plutonium-239, the main fissile material used to make atomic bombs. It was the largest quantity of weapons- quality nuclear material so far uncovered on its way to the black market, although it was still a long way from the eight kilogrammes needed to make a bomb.

The suitcase arrived in Munich aboard a Lufthansa flight from Moscow, allegedly the first taster of a total delivery of four kilos, almost enough for an atom bomb. Picked up with it were two Spaniards and a Colombian. Also on the plane was Russia's deputy minister of atomic energy, Viktor Sidorenko, whose colleagues in Moscow still insist not a single gramme of plutonium is missing.

When Soviet scientists exploded their first atomic bomb in the deserts of Kazakhstan in 1949, Stalin lavished them with favours. The designers received the title Hero of the Soviet Union, large cash bonuses, new cars and dachas in the tightly- guarded village of Zhukovka, in woods outside Moscow.

One of them is still alive. Yuli Khariton still has a personal train carriage to travel between Moscow and the laboratories at Arzamas-16, southwest of Nizhny Novgorod, formerly Gorky. But today conditions at Arzamas-16 have no smack of privilege. Morale and living standards are so low among staff there that they wrote to President Yeltsin last December threatening to go on strike over unpaid salaries. Protest banners and posters appeared in the town, no longer entirely lost in the mists of Cold War secrecy but still closed to outsiders without permits. Russia's second main nuclear warhead design laboratory, Chelyabinsk- 70, also staged protests.

'It is not a comforting sign to see bomb designers on strike because they are not being paid,' says Stan Norris, an expert on Soviet nuclear weapons at the Natural Resources Defence Council in Washington. 'Ninety-eight per cent want to do the responsible thing, but there are a few who do not. People in desperate situations do desperate things.'

Among those most eager to find out how desperate they are is the German government, which worries about the contacts between the former East German security services and members of the old KGB, many of whom are now in 'business'. Germany has taken the lead in accusing Russia of letting nuclear materials leak out.

Chancellor Kohl's intelligence co-ordinator, Bernd Schmidbauer, was due in Moscow this weekend to discuss the matter, but Russia, having spent much of the Cold War making sure West Germany never joined the nuclear club, is in no mood to be lectured by Bonn. President Yeltsin has promised co-operation, but no issue is more prickly.

'Western public opinion is trying to create the belief that Russia, with all its problems, is not in a position to maintain reliable controls on materials of this kind,' complained Vladimir Tomarovsky, of the Federal Counter-Intelligence Service. 'This is propaganda.'

Russians complain that the Germans, with their sting operations, have created a market in these materials where none really existed. They may have a point: it now seems that a man recently arrested in Bremen for trying to sell a small amount of plutonium may himself have been an official agent provocateur, although the authorities deny this.

The quickest route to nuclear power status for a state or political group is to buy or steal a warhead. At the height of the Cold War, Russia had as many as 45,000. The disarmament treaties known as Start I and Start II limit the US and Russia to 3,500 each. But this covers only strategic weapons. Tactical (essentially shorter-range) warheads and strategic warheads held on so-called inactive reserve - stored but not dismantled - double this number. So far, however, there is no evidence of a single warhead appearing on the market.

A slower but still fairly straightforward way to The Bomb is to obtain plutonium or highly-enriched uranium that has been produced with bomb- making in mind. American experts estimate that the 12th Main Directorate, the branch of the Russian military responsible for nuclear weapons, has about 165 tonnes of plutonium under its charge. So long as it remains in warheads it is fairly secure. Disarmament, though, entails a great deal of hasty dismantling. Russia is now taking apart up to 2,000 warheads a year and putting the plutonium into storage, mostly at Nizhnaya-Tura near Yekaterinburg and at smaller disassembly facilities known as Svatutsk-36 and Penza-19.

The weakest link in Russia's huge nuclear chain, though, is probably dozens of research laboratories, most of which do work for the armed forces but are not under the tight military supervision of the 12th Main Directorate. At the Moscow Institute of Physics and Technology at Dolgoprudy, outside Moscow, Dr Anatoli Diakov studies the problem at the Centre for Arms Control, Energy and Environmental Studies. He admits: 'Our system (of nuclear control) was built for a different time, for a different regime, for a different country.'

Finding the leak and plugging it depends ultimately on a technique borrowed from any old-fashioned murder mystery: matching fingerprints. The detectives are scientists. At the Trans-Uranium Institute in Karlsruhe, Germany, a laboratory run by the European Union's nuclear agency, Euratom, they have spent weeks studying the powder seized from the travelling salesman in Tengen.

Every batch of plutonium - a substance which does not exist in nature - carries in its nuclear make-up the signature of the reactor or enrichment facility that produced it. 'Fingerprinting is a very exact science if you have something to compare them with,' says Thomas Cochran, a leading US authority. 'If you know how a reactor ran, you can match it very closely with what it produced. It is like the FBI. If you have a fingerprint file you can match prints and names exactly. If you don't have the file, though, you are in trouble.'

Among the signs scientists look for is isotopic purity - which isotopes (slightly different varieties of an element), are present and in what proportions. In plutonium, bomb makers require a high concentration of the isotope plutonium-239. In a typical Soviet warhead, the experts say, this isotope is present with a purity of 94 per cent. Like cocaine, the higher the purity, the more expensive and more difficult to find. Also like cocaine, most plutonium has been 'cut', or mixed. It is 'dirty'.

The batch seized from Jaekle's garage, though, turned out to be an aficionado's delight: six grammes of 'super- grade' plutonium-239. Its purity was a remarkable 99.7 per cent. This is too high even for bomb makers and is usually only used to help calibrate instruments. For scientific detectives, though, this rare quality was very useful, since it narrowed sharply the number of suspects.

A further clue to its provenance came from the glass splinters found in the lead cylinder: remnants of a broken test- tube or some other container. Bits of brush suggested it had been swept up at some point.

The full analysis of the find fills some 50 pages. For the next step, to identify the point of origin, they need access to the 'fingerprints' of likely suspects in the former Soviet Union. For this they must turn to spies. American and European intelligence services have put great effort into establishing data banks on the technical signatures of nuclear facilities across the former Soviet Union.

It is not easy. Take the Kurchatov Institute in Moscow. Set up in the 1940s under the elusive title Laboratory No. 2, it has since dropped its Cold War disguises. But the doors have not exactly been thrown open. Vladimir Kuznetsov, a nuclear engineer whose job it was until 1992 to inspect the institute for safety, says secrecy remains an obsession. 'Everything is secret, top secret or extremely secret. The culture is 'burn before reading'.'

Because the West's fingerprint file is far from complete, determining place of origin for smuggled samples is an inexact science. Euratom announced last week that it narrowed the field to three or four facilities, among them Arzamas-16, Chelyabinsk and Yekaterinburg. In private, though, experts point to Arzamas-16 as the most likely suspect for the Tengen plutonium. According to Mark Hibbs of Nucleonics Week, its purity of 99.7 per cent matches closely the fingerprint of an enrichment plant known as S-2 at Arzamas-16.

The purity of what turned up in Mr Jaekle's garage also reminded several scientists of a paper they had heard last autumn at a conference in New Mexico. It had addressed this very issue of ultra high-purity plutonium-239. Its author was Nikolai Polynov - a high-energy physicist at Arzamas-16.

This particular mystery seems close to being solved. Many loose ends, though, remain. If it was produced in Arzamas, was it stolen from there or from another laboratory to which it could have been sent for research? It may not be suitable for making a bomb, but what does its release say about Russian security? Nor are there likely to be many clear answers from the analysis now under way of three other batches of nuclear material found since May in Germany.

In the end, the diplomatic fallout from the entire drama may prove more damaging than the danger posed by the tiny samples so far being smuggled out. Russia's system, though, has clearly sprung a leak.

(Photograph omitted)