Annex 5. Ending the Production of Highly Enriched Uranium for Naval Reactors

    In December 1993, the U.N. General Assembly adopted, without dissent, a resolution calling for the negotiation of a fissile material production cut-off treaty (FMCT). In this resolution, the FMCT was described as a "non-discriminatory, multilateral and international and effectively verifiable treaty banning the production of fissile material (highly enriched uranium or plutonium) for nuclear weapons or other nuclear explosive devices." The 2000 Review Conference of the parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) called for the completion of negotiations on the FMCT within five years. The FMCT would serve as a key building block in the nuclear weapons non-proliferation and disarmament regime by putting a cap on the stocks of fissile material available for nuclear weapons. These stocks could then be reduced by verified, irreversible disposition.

However, the FMCT, as currently envisioned, has a potential loophole because it would permit the continued production of weapon-usable fissile material for use in military reactors. It would therefore leave open a potential diversion route whereby countries could produce or acquire weapon-usable fissile material and remove it from international safeguards under the pretext that it was to be used in military reactor fuel.

Currently, the United States and the United Kingdom use "weapon-grade" uranium containing more than 93 percent uranium-235 (U-235) to fuel their naval reactors, and Russia uses HEU containing more than the 20 percent U-235, defined by international agreement to be the threshold for direct weapons-usability. France has fueled some of its submarines with HEU but has decided to shift to low-enriched uranium (LEU) containing less than 20 percent U-235. China reportedly uses LEU fuel. In the past, both the United States and the Soviet Union built HEU-fueled nuclear reactors for other military purposes.

In this essay, we propose that the ban in the FMCT be extended to the production of weapon-usable fissile material for any military use, including naval reactors. Those countries currently using HEU in military reactors could fuel their reactors during a several-decades-long transition period with HEU recovered from excess nuclear warheads. Follow-on generations of nuclear-powered submarines and ships could be designed to use LEU. Any countries joining the nuclear navy "club" would design their propulsion reactors to use LEU - as India and Brazil currently plan to do. There appears to be no significant interest in other types of military nuclear reactors today. However, if military interest were to revive, LEU fuel could be used in land-based reactors just as in naval reactors. Our hope would be that orbiting military reactors could be banned.

The NPT Loophole

    Most countries that operate nuclear navies do not plan to ever reintroduce into peaceful nuclear activity the fissile material remaining in spent naval reactor fuel. U.S., British, and French spent naval reactor fuel is being stored pending the availability of final disposal in a geological repository. It will therefore remain indefinitely in a military form whose design is considered highly classified. Currently, Russia is reprocessing spent naval reactor fuel in order to recycle the recovered uranium in power reactor fuel. However, it may well discontinue doing so.

Thus the NPT appears to allow any non-nuclear weapon state to launch a military nuclear reactor program and fuel it with weapon-usable uranium removed from under international safeguards, while blocking any effective international effort to verify that no material has been diverted to weapons use. The FMCT, as currently conceived, would propagate the same problem to the weapons states as well.

It would not be possible to close completely the NPT loophole by preventing its duplication in the FMCT. Countries could still shift fissile material produced before the FMCT came into force from safeguarded civil uses to unsafeguarded military uses. Existing civilian stocks of HEU are small (about 20 tons16) in comparison with military stocks, however, and could be reduced further as HEU-fueled research reactors are either converted to LEU or shut down. Although hundreds of tons of excess military HEU are being transferred by Russia and the United States to civilian use, virtually all of this HEU is being blended down to LEU for use in power-reactor fuel.

Therefore, if the United States, United Kingdom, and Russia decided to join the other nations already using LEU fuel in their naval reactors in a formal commitment not to produce HEU for military reactors, their large stocks of excess HEU would allow them to make a several-decades-long transition to LEU fuel. In the longer term, if disarmament reduces military stockpiles of fissile materials to much lower levels, an FMCT ban on HEU production for any military purpose would become an invaluable barrier to clandestine nuclear weapon production by nuclear weapon states as well as proliferant states.

Naval Reactor Fuel Enrichment and Consumption

    The world's nuclear fleet currently contains about 170 submarines and ships, including six icebreakers and an Arctic transport operated by Russia. This is about half the size of the nuclear-powered fleet deployed at the end of the Cold War (see Table 1).

All nuclear submarines, except those built by Russia, are powered by single reactors; most Russian submarines have two reactors. The United States, Russia, and France also have nuclear-powered surface ships in their fleets, most of which are powered by two reactors each. Although, in the past, both the United States and Soviet Union experimented with liquid-metal-cooled reactors, all naval reactors in use today are of the pressurized-water reactor (PWR) type. Publicly reported enrichments of naval reactor fuel vary from weapon-grade (93 percent U-235 and above) for the United States and Britain, to five percent U-235 for China (see Table 2).

(Number = Number + under construction. For Russia not military ice breakers are included).

(1 shaft horsepower = 0.746 kilowatts; SSBN = nuclear-powered ballistic-missile submarine; SSGN = nuclear-powered cruise-missile submarine; SSN = nuclear-powered attack submarine; CGN = nuclear-powered cruiser; CVN = nuclear-powered aircraft carrier).