What fissile materials are there on Mars?

Against the background of political and economic destabilization in the successor states of the Soviet Union, the nuclear legacy of the Cold War is a particularly heavy burden on international security: Nuclear warheads are still outside Russia, and materials suitable for nuclear weapons are in some poorly guarded arsenals, in nuclear power plants and even in metalworking factories or physical-technical institutes. The several thousand employees in the nuclear weapons laboratories and production facilities are just as affected by rising unemployment and falling living standards as other citizens of these countries. There is a great risk that nuclear material will be stolen or that nuclear weapons experts will migrate to states who want to make use of their expertise. Can this complex be brought under control and the proliferation of nuclear weapons and their components prevented?

There have been isolated, rather harmless cases of nuclear smuggling in the past. Since the borders between Eastern and Western Europe have been largely open, such activities have increased at an alarming rate. While only four attempts to illegally trade in nuclear material were known in 1990, there have been well over a hundred in each of the last three years. Usually traders offered weapons-grade uranium or plutonium; As it turned out, however, all such offers were fabricated with fraudulent intent - nothing or only non-weapons-grade material was subsequently delivered.

Even the radioactive substances that could be seized in various actions within Germany or at the borders up to the beginning of 1994 turned out to be of no military relevance. The following were confiscated:

- Natural or weakly enriched uranium in tablet or powder form, as is typical for the manufacture of fuel elements for nuclear power plants;

- Ionization sources and metal disks with a few milligrams of plutonium, as used in smoke detectors of Russian origin or in test emitters for calibrating measuring devices;

- Cesium-137 sources from holdings of the former Soviet army, which were used in decontamination experiments and exercises;

- Radiation sources with cobalt-60, strontium-90 or californium-252, as used in medical devices or scientific experiments.

Although some of these substances are likely to come from military sources, they are not actually part of the nuclear weapons field. Their appearance on the black market does not allow any conclusions to be drawn about a possible trade in weapons-grade nuclear material. However, due to their sometimes considerable radioactivity, if improperly handled they can threaten the health of people (mainly the smugglers themselves). In addition, it cannot be ruled out that criminal organizations or terrorists will attempt to blackmail such substances - similar to poisons and explosives - by threatening environmental pollution.

With the discovery of a not inconsiderable amount of plutonium in May 1994, however, nuclear smuggling took on a completely new dimension. For the first time, material suitable for nuclear weapons was accessible to everyone. But which substances can be classified under this term?

Dangers of proliferation from materials suitable for nuclear weapons

Each nuclear explosive device contains several kilograms of fissile material with a specific isotopic composition. If uranium is used for this purpose, it must consist of at least 80 percent of the isotope uranium-235. Because natural uranium only contains 0.7 percent of this (the rest is non-fissile uranium-238 with traces of uranium-234), it has to be enriched accordingly in a complex and technologically demanding process. In contrast to such highly enriched uranium (HEU), the weakly enriched uranium used in fuel rods for nuclear power plants contains a maximum of three percent uranium-235 and is therefore not suitable for use in weapons.

The artificial element plutonium is also used as a fissile material. It is produced in nuclear reactors together with various other radioactive products and can be extracted from the fuel elements using chemical processes. The proportions of the plutonium isotopes formed vary depending on the type of reactor and the burning time. Attempts are made to maximize the proportion of Pu-239 for military purposes, but in principle almost all other isotope mixtures are also suitable for use in weapons.

Highly enriched uranium and plutonium are also used outside of weapons technology, which increases the number of sources from which these substances could possibly be diverted. Some countries - including Russia - use HEU to drive nuclear submarines. It is also used as fuel in some civil research reactors.

Because of the associated risk of proliferation, great efforts have been made worldwide, with some success, to use a less explosive fuel in such plants. Some industrialized countries also use plutonium in the form of mixed oxide fuel elements (MOX) in light water reactors or in breeder technology. All such operating and production facilities are therefore possible sources of smuggled materials.

Explosive finds

The first significant amounts of material suitable for use in nuclear weapons were discovered in a mixture of elements weighing 56.4 grams, which was seized on May 10, 1994 in Tengen in southern Germany; as later analyzes showed, it consisted of ten percent plutonium. Its isotopic composition was astonishing, because there is no reactor that could have produced such a mixture. The proportion of plutonium-239 turned out to be extremely high, other isotopes were largely absent. Such a high concentration could only have been achieved through an enrichment process - a process that is completely unusual for this fissile material and technically very complex, which would also not be necessary for use in nuclear explosive devices. Apparently this material was intended for research purposes and was probably not produced in large quantities; but about 20 nuclear research institutes in Eastern Europe had received samples of this substance.

One month later, on June 13, 1994, the authorities in Landshut seized 0.795 grams of uranium powder (sintered uranium dioxide) with an enrichment of 87.8 percent - the first HEU ever found, albeit in an insufficient amount for weapons purposes. A multiple of this, namely three kilograms, with the same degree of enrichment was confiscated in Prague in December 1994. One possible source could be the production of fuel for submarine reactors.

The third case of smuggling of military-relevant nuclear material in Germany, which triggered strong press coverage and heated discussions, was discovered on August 13, 1994 at Munich Airport: 560.25 grams of MOX with a plutonium content of 360.12 grams - the largest amount of this material that has been found in the hands of unauthorized persons. But not only this high plutonium content is unusual, but also the isotopic composition: The proportion of plutonium-239 is higher than in civilian reactor plutonium, but lower than in weapons plutonium. It could be fuel for a prototype fast breeder.

It is true that none of the finds can be proven to come from the Russian military nuclear complex. Nevertheless, the diversion of weapons-grade material from the civilian or conventional military sector also poses a considerable risk of proliferation. If one of the states that are known to strive for possession of nuclear weapons should get hold of these materials, it could manage the construction of a bomb much more quickly.

Mysterious fabric red mercury

Due to the explosive nature of these cases, the media reported in great detail about other finds from that time; However, they all belong to the category of non-proliferation-relevant smuggling attempts described at the beginning.

A strange substance, called red mercury, plays a special role in this. It was said that Russian researchers had already used this material to build miniature nuclear weapons the size of a beer glass; and because it is already being smuggled everywhere, terrorists will soon be able to use it to blow up entire cities.

However, the alleged chemical and nuclear physical properties of this substance - both as a high-energy explosive and as an excellent neutron reflector - do not stand up to scientific scrutiny. Even if there were a substance with such qualities, the construction of nuclear explosive devices would not be easier because the basic component would still be fissile plutonium or HEU; the technical effort for the ignition technology would not change either.

From admixtures of mercury compounds in some of the smuggled finds of the last few years, some reporters in fact concluded that red mercury existed; In truth, they were all substances that anyone can purchase cheaply - for example, as anti-rust paint, also known as red cinnabar.

Preventing Proliferation

The question arises as to whether there is also a buyer market for weapons-grade nuclear materials in addition to the supplier market. The five so-called established nuclear weapon states - USA, Russia, China, France and Great Britain - are ruled out as potential buyers. (However, the USA flew several hundred kilograms of HEU from Kazakhstan in November 1994 to prevent it from being stolen from the barely guarded camp.) Israel, India and Pakistan, which are generally believed to also have nuclear weapons, also have their own production capacities for Plutonium or HEU in sufficient quantities and are therefore not dependent on methods such as nuclear smuggling.

Iraq, whose advanced nuclear weapons program was exposed after the end of the Gulf War, and North Korea and Iran, which are also allegedly seeking an option for nuclear weapons, are different. However, it is unlikely that these states will seek weapons-grade material on the black market at this very moment, because if such actions become known they would have to fear economic, technological and political projects: North Korea would like civilian nuclear technology worth several from the USA Receive billions of dollars in return for giving up its previous nuclear weapons activities; Iraq seeks to have UN sanctions lifted, and Iran is keen to demonstrate its non-proliferation reliability over a boycott of civilian nuclear technology.

In principle, however, it cannot be ruled out that other countries may use nuclear smuggling, even though there have not yet been any concrete indications of this. Such a nuclear weapon aspirant could certainly try to gain access to the stocks in the former Soviet Union - most likely in one of the ten cities, which have been closed to this day, in which the research and production facilities of the Russian military nuclear complex are located (picture).

Whether - as feared - a kind of mafia is actually organized there, which smuggles nuclear materials in a professional manner and on a large scale to the end users, depends not least on the social situation of the employees in these facilities. The tendencies towards dissolution and drastic changes can no longer be overlooked here.

There is also fear of an exodus of experts who could make substantial contributions to a nuclear weapons project with their knowledge. The group in question probably includes around 10,000 to 15,000 employees. However, this also includes experts on partial aspects such as enrichment, as it is also found in various industrialized non-nuclear weapon states such as Germany. Around 2,000 employees should have specialized knowledge directly related to the design and operation of nuclear weapons.

Various programs with financial support from Western countries have already started to offer the scientists and engineers concerned from the Commonwealth of Independent States incentives to use their skills for peaceful purposes in their own country. At the end of 1992, after long negotiations, the International Technology Center was founded in Moscow, which serves as a point of contact and intermediary for projects in applied research in the areas of environmental protection, energy production and the safety of nuclear facilities. The European Union, the USA and Japan are mainly involved in the financing with a total of around 80 million dollars.

Another measure has become known under the term "Nunn Lugar Money", named after two American senators. It is intended to support the dismantling of Russian nuclear weapons. However, the process has become more complicated because the United States has asked Russia to be more transparent than it was prepared to allow when dismantling its warheads. In the meantime, however, there is a noticeable rethinking here. Because the passage through the bureaucratic authorities of the USA took so long, part of the money has already expired.

In Russia, people are skeptical or even suspicious of these programs: many fear that only the valuable knowledge of Russian scientists should be spied on, but that the money is primarily intended for Western industry.

The European Atomic Energy Community (Euratom) is pursuing a different approach, setting up a training center for inspectors and operating staff in Russia itself and organizing seminars and guest visits at its headquarters in Brussels. The aim is to create a material balance system based on standards similar to those of Euratom.

In the long term, international controls (so-called safeguards) for plutonium and uranium must also be introduced in the nuclear-weapon states, as they have been in the non-nuclear-weapon states for a long time. Even if the diversion of such small quantities as has emerged in the most recent smuggling cases could not be determined, it would result in a discipline and also a national and central registration of all stocks, which does not yet exist in Russia. The military fissile material should also be subject to these international controls. Before that happens, there are still many strenuous negotiations to be conducted - but this idea is no longer unrealistic under today's circumstances.

From: Spectrum of Science 3/1995, page 116
© Spektrum der Wissenschaft Verlagsgesellschaft mbH

This article is contained in Spectrum of Science 3/1995