Abstract
The U.S. navy is close to meeting one of its prime technological goals: The first new nuclear attack submarine of the Virginia-class will put to sea in 2004 with a lifetime reactor core. The new propulsion system, which increases operational time by eliminating the need for refueling, has won praise for its greater efficiency and affordability. But this technological revolution only highlights the fact that a review of U.S. naval fuel stockpiling policies is long overdue.
Although it has more than adequate fuel stocks, the navy is keeping all its stockpiling and production options open. Troublingly, this includes placing restrictions on U.S. declarations of excess fissile material, and asserting the right to withdraw fissile material from international safeguards. Worse yet, by seeking to exempt the production of weapon-grade uranium for naval purposes, it could undermine international aspirations for a treaty ending the production of fissile material. At the same time, the navy's policy of secrecy limits opportunities for independent review and public debate. None of this is of benefit to U.S. nuclear security.
Enough already
As is true of other navies, the U.S. Navy maintains a high degree of secrecy about its nuclear operations. Very little is known about its nuclear fuel designs or propulsion technology. Even fuel consumption levels and future fuel requirements are secret. In 1995, however, the navy estimated that it had enough highly enriched uranium to cover its requirements until about 2006. Forty percent of the navy's combat ships are nuclear propelled. The United States now operates 103 naval reactors, including four naval prototypes, a research submarine, and the multiple reactors in the nine nuclear-powered aircraft carriers. In 1995, when the navy operated 158 reactors, the annual burn-up of uranium 235 in the entire U.S. nuclear fleet was approximately 1.1 metric tons. Today, based on the number of operating reactors, the navy's total uranium 235 burn-up is likely to be around 700 kilograms per year.
Since 1992, when the division of the Portsmouth, Ohio enrichment plant that made weapon-grade uranium closed, U.S. naval reactors have drawn from existing military stocks. This has affected both the quantity and quality of uranium that has been declared “excess,” and taken out of military stocks. This uranium is intended to be made available for down-blending and subsequent use in commercial power plants under international supervision. In 1996, 174.3 tons of highly enriched uranium were declared in excess of national security needs. However, with the exception of the first 10 tons removed from the military stockpile, all the material the navy considers usable as naval fuel has been kept in military reserve. None of the material the navy has a real interest in has been declared excess. A closer look reveals that most of the “excess” material is of a significantly lower enrichment level than the weapon-grade material (enriched to 90 percent or above) that the navy uses in its reactors.
In addition to carefully planned stockpiling, technical naval reactor core developments will represent new and unparalleled fuel-saving benefits for the navy. The navy is now designing reactor cores that are expected to last 50 years in aircraft carriers, 40 years in missile submarines, and 30 years in attack subs. These extended lifetimes are likely achieved by making more uranium 235 available for fission in the reactor cores and by optimizing the burnable absorbers to control the neutron flux in the core throughout its service life.
Traditionally, an older reactor would undergo one or two refuelings in its operational life. But with the new technology, one core will suffice, which suggests a two-thirds reduction in fuel demand per reactor in the decades to come.
Moreover, the dismantlement of nuclear weapons means that more highly enriched uranium is becoming available to the navy than it can possibly consume. Since the end of the Cold War, the United States has dismantled more than 13,300 nuclear warheads and bombs, at a rate exceeding 100 per month. With an average of 20 kilograms of weapon-grade uranium in each warhead, a single month of warhead dismantlement could represent some three years of burn-up of uranium 235 for the whole U.S. Navy. The chance that the navy could run out of fuel seems truly remote.
The naval exception
In September 1993, President Bill Clinton announced that the United States would place material in excess of its defense needs under International Atomic Energy Agency (iaea) safeguards. This was done to demonstrate the transparency and irreversibility of the dismantlement process and to underscore the U.S. commitment to the Nuclear Non-Proliferation Treaty. Excess material under international control cannot be withdrawn from safeguards for nuclear weapons or for any other nuclear explosive purpose.
The navy acknowledges that iaea safeguards on excessive stockpiles are crucial for shaping nonproliferation and arms control policy, yet its policies are directly contradictory.
Despite the 1993 pledge, the navy maintains its right to withdraw material from safeguards to use as naval reactor fuel. The benefits of this exception are minimal— none of the material currently under safeguards is of interest to the navy anyway—nor is the navy ever likely to invoke the option. It would be an uphill battle politically to try.
The navy's insistence on maintaining the option to withdraw material from safeguards may undermine the important principle of irreversibility. IAEA supervision is a practical implementation of this basic principle of contemporary nuclear arms control.
A fissban exception too?
A treaty to ban the production of fissile material for nuclear weapons and other nuclear explosive devices is an important long-term security-building measure and the natural next step for global nuclear disarmament and non-proliferation. International obligations under the Nuclear Non-Proliferation Treaty call for such a treaty by 2005.
This “fissban” treaty, which has been near the top of the U.S. arms control agenda since the early 1990s, would cap the production of fissile material for nuclear devices. There is no way to reach the ultimate goal of nuclear disarmament without it, as the treaty would put a ceiling on the nuclear weapons to be produced.
Materials for naval propulsion, however, are not likely to be included in the production ban. After pressure from the navy, the United States expects a cutoff that would prohibit the production of weapon-grade uranium, plutonium, and uranium 233 for nuclear explosives, but allow the production and use of highly enriched uranium for non-explosive military uses like naval reactors.
This naval-fuel-cycle exception could therefore become a backdoor for nuclear weapons proliferation. Treaty exceptions for navies would render the fissban inconclusive, opening the way for clandestine fissile material production and mutual mistrust.
Time to review
Non sibi sed patriae—not self but country—is often cited as the navy's motto. But current naval fuel policies may endanger the long-term nuclear security benefits associated with increased controls on stocks of fissile material.
To get in line with contemporary fissile material nuclear security policies, a thorough and open investigation of the navy's nuclear fuel consumption and supply is needed, as is increased transparency regarding fissile material stockpiles destined for naval use. This uranium will somehow have to be accounted for, and assurances that it is not being diverted to weapons should be made.
The U.S. review should consider several options in particular: placing more uranium of higher enrichment levels in the excess category, abandoning the option to withdraw naval reactor fuel from under international safeguards, and finding alternate ways of dealing with genuine naval fuel needs under a future fissile material cutoff treaty.
