Nuclear Monitor Issue: 

(February 13, 2004) The decision regarding where the new International Thermonuclear Experimental Reactor (ITER) will be located, Cadarache (France) or Rokkasho Mura (Japan) is expected to be resolved when ITER partners meet (at a yet unknown date). Dr. Andre Gsponer and Dr. Jean-Pierre Hurni, director and senior researcher at the Swiss based Independent Scientific Research Institute (ISRI), have published a report on the proliferation aspects of ITER and fusion research.

(603.5574) WISE Amsterdam - There are several valid arguments against the construction of the ITER reactor and continued research into fusion energy; tremendous costs, safety risks, radioactive waste to name a few. The ISRI researchers focussed on the strategic-political and military-technical implications of the fusion research and reviewed two aspects of the proliferation risk: the availability of tritium, which can be used both in fusion reactors and nuclear weapons, and scientific knowledge on fusion physics.

Tritium and nuclear weapons
The oldest design for nuclear weapons consists of pure high-enriched uranium and/or plutonium materials. The Nagasaki bomb for instance contained 6 kilograms of plutonium and 120 kilograms of uranium; to compress the materials and start the chain reaction, 2,500 kilograms of high explosives surrounds the nuclear core making the bomb large (1.3 meters), heavy (about 3,000 kilograms) and deliverable by airplane only.

"Boosting" technology has made it possible to decrease the weight and size of a weapon. Its core materials remain the same but prior to detonation, the center is injected with a mixture of deuterium-tritium gas. Compressed by chemical explosives, an initial chain reaction begins with subsequent X-rays and neutrons heating the gas at the center. The pressure and temperature of the gas is sufficient to start the fusion reaction, the mixture rapidly burns out generating an intense pulse of neutrons. These fusion neutrons cause the rest of the core to fission, which generates most of the yield of the explosion.

In "boosted" bombs, fusion is used to produce neutrons for fission making them very different from powerful "hydrogen" or "thermonuclear" bombs where fusion itself is more important and causes the main yield.

A few grams of tritium are sufficient to "boost" bombs made of a few kilograms of military- or reactor-grade plutonium making them smaller and lighter than conventional designs and deliverable by missiles instead of bomber planes. "Boosted" bombs contain only 4 kilograms of plutonium or 12 kilograms high enriched uranium, weighs less than 100 kilograms and is about 30 centimeters in diameter. Their reduced size and weight also makes these weapons a terrorists object of desire given that they could be deliverable using a vehicle and do not require testing.

"Boosted" bombs can be perceived as 'user friendly' in that the prospect of accidental nuclear explosion is considered near impossible. In storage, the deuterium-tritium gas is contained in a separate reservoir outside the core, should an accidental explosion of the chemical explosives components occur, the relatively small amounts of plutonium or uranium involved would not be sufficient for a full nuclear explosion. This means that reactor-grade plutonium, which is relatively unstable and prone to spontaneous fission, could be utilized at significantly reduced risk given the small amounts of material required in a "boosted" bomb.

"Boosting" is essentially used all modern nuclear weapons, including those in Israel, India, Pakistan and possibly North Korea. The development of "boosted" bombs thus confirms the tremendous importance of tritium to the issue of non-proliferation of fission weapons.

Tritium and ITER
At present, only small amounts of tritium are shipped globally for industrial or scientific use, it is estimated that the current world market corresponds to the shipment of about 100 grams annually, mostly produced in Canada. Tritium is already used for various industrial applications, for example luminous dials and gun sights, but only in minute quantities (micrograms). In comparison the ITER project will require the international shipment of large amounts of tritium.

Once operational, ITER's tritium inventory will be about 2 kilograms with an annual consumption of 1.2 kilograms: amounts comparable to several thousands of "boosted" nuclear weapons. To operate on a commercial-scale, reactors would require an inventory of 10 kilograms. Currently, the total amount of tritium in the U.S. weapons stockpile is some 100 kilograms, an average of 10 grams tritium per warhead so the inventory of 2 kilograms in the ITER will be enough to "boost" 200 nuclear weapons.

The expected six annual transports of tritium to the ITER reactor will pose certain risks, theft or hijack being of most concern. Although the tritium will most likely be produced in Canadian CANDU reactors, it is possible for a special facility (like an accelerator) to be built in the host country. This would go some way to addressing the issue of unsafe transports but does not resolve the threat of theft. It is much easier to conceal significant amounts of tritium and given that the required amounts are smaller (grams instead of kilograms), much less radioactive and more difficult to detect, effective procedures will need to be put in place to ensure the security of the material.

After withdrawing from the ITER project five years before, in January 2003, the U.S. decided to rejoin the project. This is seen as a calculated political move to gain influence over the project from a proliferation view. Since its withdrawal in 1998, Pakistan and India have conducted nuclear tests and North Korea has been working on nuclear weapons. As the (suspected) weapons of these countries are deliverable by missiles, they are likely to be "boosted" bombs, containing tritium. For this reason, any international enterprise, like ITER, in which large amounts of tritium are to be used becomes a sensitive undertaking with which the U.S. must participate in order to exert as much influence as possible.

Other fusion proliferation risks
Tritium may be the most important proliferation risk in fusion reactors, but there are other proliferation aspects to consider.

Every fusion reaction produces neutrons that can be used for breeding technologies: the wall of a fusion reactor could be covered with a blanket of uranium to breed plutonium. This advanced concept of fusion is called the "fusion-fission hybrid" and such a fusion reactor could be misused to produce weapons-grade plutonium. It is calculated that a fusion-fission hybrid could breed more than 5,000 kilograms of plutonium annually, compared with "only" 500 kilograms in a conventional heavy-water reactor of the same power.

Fusion research has another spin-off effect: the development of super-conductive magnets, which is of importance to strategic military developments in outer space, ballistic missile defense and electromagnetic guns.

Another technology being studied for fusion energy is the Inertial Confinement Fusion (ICF). In ICF, tiny pellets (containing deuterium-tritium) are put in a reaction chamber and targeted by high-energy lasers. ICF technology enables the physics of nuclear weapons to be studied on a laboratory-based scale, which could make any clandestine research difficult to detect.

ICF technology could result in a fourth generation of nuclear weapons without plutonium or uranium. In such weapons, deuterium-tritium pellets could be detonated with the lasers instead of by the conventional chain reaction, which will require the development of much smaller high-energy laser devices. Any country with an understanding of ICF and laser technology could develop such a weapon easily without being detected.

The underlying technology and knowledge of high-energy lasers for ICF could be used to develop laser enrichment technology, which could make it possible to enrich uranium to 100% uranium-235 (weapons quality) in one stage.

The ISRI researchers concluded that "siting ITER in countries such as Japan, which already has a large separated-plutonium stockpile, and an ambitious laser-driven [fusion program], will considerably increase its latent (or virtual) nuclear weapons proliferation status, (i.e. its ability to manufacture nuclear weapons on short notice) and foster further nuclear proliferation throughout the world".

Although ostensibly a non-nuclear weapons state and proponent of disarmament, Japan is confronted with the weapons capability of other countries in the Asia region (Pakistan, India, and North Korea). With the possible siting of ITER in Japan, the country would have full access to large-scale tritium technology and with its stockpiled plutonium and reprocessing options all necessary technology to produce "boosted" nuclear weapons will be at its disposal. Regardless of Japans intent, the siting could have a destabilizing effect in the region and may push other countries to increase their efforts for more advanced nuclear weapons.

Source: ITER: The International Thermonuclear Experimental Reactor and the Nuclear Weapons Proliferation Implications of Thermonuclear-Fusion Energy Systems, A. Gsponer and J-P. Hurni, ISRI, 4 February 2004. To be found at

Contact: Independent Scientific Research Institute, P.O. Box 30, CH-1211 Geneva-12, Switzerland Email:



The Watts Bar NPP in the U.S. has been used for weapons-grade tritium production since October 2003. Rods with lithium have been inserted between the uranium fuel elements and the irradiation by neutrons converts it to tritium. The production of new tritium for the U.S. weapons stockpile is considered necessary as tritium (with a half-life of 12 years) decays by about 5.5 percent per year however production in the Department of Energy (DOE) reactors halted due to shut downs for safety reasons. In order to prevent the costly building of new reactors, the DOE chose to use civilian NPPs, a plan that raised protests from many anti-nuclear organizations. The proposed Watts Bar and Sequoyah reactors are vulnerable to severe accidents as their containment systems are considered to be inadequate, which will make also them more vulnerable to terrorist attacks, especially if they become "part of the nuclear weapons complex". Objections were not heard as they were considered "inadmissible" and thus no public hearings were ever held.

There are doubts as to whether tritium production is truly necessary, under the START II and 2002 Moscow treaties, tritium will be extracted from dismantled nuclear bombs. Only 240 lithium rods were loaded in Watts Bar, not the 2,304 that had been approved in the license. No rods at all were loaded in the Sequoyah reactors. The rods will be de-fueled in April 2005 and transported to the Savannah River Site, where an extraction facility will be operational in late 2007. It is possible that the sharp reduction in rod irradiation is simply due to the construction delay, but it is also possible that DOE is now recognizing what many have said before - that the need for new tritium has been exaggerated.
Bulletin of the Atomic Scientists, January/February 2004