rational defense

Position Paper #1 — Aggressively pursue the most viable means of ensuring the long-term sustainability of the U.S. nuclear deterrent by building and fielding the Reliable Replacement Warhead.

RD has consistently argued in favor of the Reliable Replacement Warhead (RRW) on the basis that it is most viable means for ensuring the long-term sustainability of the U.S. nuclear deterrent while minimizing the chances of further nuclear testing.

The precise nature of nuclear weapons design is obviously highly (and legitimately) classified. But while the finer points of the technical debate are obviously limited to experts and a select few elected representatives, the broad strokes of the issue at hand are clearly discernible. (Indeed, RD has been founded in part on the belief that such broad strokes can and must be discerned and understood.)

The RRW program proposes modest and conservative design changes to Cold War-era warhead architecture that would seek to maximize safety, reliability and maintainability with an eye towards an essentially indefinite service life. With only modest and conservative tweaks, RRW is intended to be certified without requiring nuclear testing (though there admittedly cannot be any absolute guarantee of that in such an endeavor). New warheads would then be built to serve as the mainstay of the American nuclear deterrent for the foreseeable future.

This proposal has experienced strong opposition from many in the arms control community, and the program was consistently denied funding by the 110th Congress. With an even stronger Democratic 111th Congress now in session, prospects appear bleak. In any event, little is likely to happen before the Congressional Commission on the Strategic Posture of the United States reports its findings April 1 (the Commission released an interim report last Dec. 15). Secretary of Defense Robert Gates is also moving to accelerate the 2010 Quadrennial Defense Review process, which will help chart the Pentagon’s course well into the next decade. So despite the opposition of the 110th Congress, the issue of the RRW remains very much alive.

Indeed, Gates has argued consistently for RRW — most prominently in a speech late last year to the Carnegie Endowment for International Peace. Gates expressed grave concerns about the long-term sustainability of the American nuclear arsenal and warned that without RRW, the existing arsenal would eventually need to be subjected to nuclear testing as it continued to age in order to maintain a high degree of confidence in reliability.

To have meaning, a nuclear deterrent must be credible in not just its existence but the much more complicated willingness to actually employ it — at the very least in a second or retaliatory strike. Inextricably linked to this is the issue of confidence. Both the government that commands the arsenal and those it is intended to deter must be confident that the delivery systems and the warheads actually work.

The incredible complexity of modern nuclear weapons makes that confidence a challenge — especially over time. Though obviously quite classified, current American warheads are widely thought to be two-stage thermonuclear designs, the newest with a non-spherical primary shaped like an egg. Translation: two distinct, but carefully timed nuclear chain reactions that must be precisely timed to a fraction of a fraction of a second. The non-spherical detail is important because it makes the already enormously complex implosion design even more intricate and complicated. Also hardened to endure not only the acceleration of launch, the cold vacuum of space and the immense heat of reentry but also electromagnetic interference, these warheads are then crammed into a steeply conical reentry vehicle composed of advanced composites to endure the heat of friction during reentry at extremely high speeds. These reentry vehicles are as small as six feet tall and less than two feet wide at the base. In sum, it is without exaggeration one of the most complex devices ever constructed by man.

This complexity makes reliability particularly challenging. The U.S. Los Alamos and Lawrence Livermore National Laboratories use the world’s most powerful supercomputers to model the effects of age on the existing arsenal as part of the current Life Extension and Stockpile Stewardship Programs (LEP and SSP).

But there are necessarily limits to what LEP and SSP can do. This has nothing to do with LEP and SSP and everything to do with the warheads they are working with. While safety, reliablitiy and maintainability have obviously always been key design considerations for nuclear weapons, other factors were extremely important in the Cold War arms race, during which and for which every warhead now in the U.S. arsenal was designed. For instance, high yield-to-weight ratios became an important metric in the Cold War, especially when mounting multiple warheads on a single missile (known individually as a multiple independently targetable reentry vehicle, or MIRV). And maximizing accuracy was essential for counterforce targets like hardened missile silos. Accuracy favored particularly steep and narrow reentry vehicle cones (which were more stable during reentry and were almost certainly a key factor in the use of narrower non-spherical primaries).

Obviously weight and accuracy remain essential design considerations. But in the days of the Cold War, their importance was paramount, and design compromises were inevitably made that complicated warhead architecture from a sustainability standpoint. Indeed, at that time warheads were regularly displaced by newer, more advanced designs. The continual cycle of upgrades and replacements was simply part of the Cold War design paradigm. None of the warheads now in the arsenal would have been designed with the underlying consideration that they would be serving in an operational status essentially indefinitely.

Any nuclear warhead — like any weapon system — will invariably become increasingly complicated to retain in an operational status as it ages. But the existing arsenal was not optimized with such considerations in mind and consequently the challenges of sustainment will almost certainly come to a head faster.

Ideally, these mounting challenges to certification and thus confidence would be spotted years in advance, so that there might be time to begin designing a replacement warhead at that point. However, the current circumstances and the prohibition on nuclear testing now effectively in force (in practice, if not yet law) make the issue urgent even if (hypothecially) current modelling does suggest that LEP and SSP can continue to ensure confidence for some time to come.

This is because the engineers that had first-hand experience with nuclear weapons design during the Cold War and in the era of nuclear testing are aging. That expertise and experience not only would likely ensure a better design, but would also almost certainly play a role in minimizing the risk of nuclear testing becoming necessary for certification. As these engineers age and approach retirement, they will be transfering their knowledge and experience to the next generation of nuclear weapons engineers. But something will inevitably be lost in that transfer, and the subtlety and nuance of design work

As such, if the primary goal for the United States is to sustain a decisive U.S. nuclear deterrent indefinitely and to do so without full scale nuclear testing, the answer is RRW. RRW maximizes the long-term sustainability of the arsenal by being tailored for that mission. Pursuing RRW now also maximizes the experience and expertise of Cold War weapons engineers and consequently helps minimize the chances for full scale nuclear testing.

The new warhead would also have the benefit of drastically reducing the size of the nuclear stockpile by maximizing confidence and minimizing the need for hedge stocks, when compared to current requirements. The result is a streamlined and more cost-effective nuclear enterprise.

In sum, further disarmament is absolutely in the cards. But total disarmament — ‘getting to zero’ — remains unforeseeable in the current geopolitical climate.[1] While some may consider that an admirable goal, it would be irresponsible to bank on its success in the foreseeable future. And the longer the United States relies on its Cold War-era arsenal, the closer it gets to implicating itself in a nuclear test for certification. Meanwhile, the longer RRW is pushed to the right, the less Cold War-era expertise and experience the program will have in the design phase.

As such, RD believes that the the aggressive pursuit of RRW is the most viable means of ensuring the long-term sustainability of the U.S. nuclear deterrent.

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1 This is hardly a minor point, but not one RD intends to delve into here. In short, every other nuclear power in the world has made choices to modernize its arsenal or is actually manufacturing new warheads to sustain its arsenal well into the 21st century. This makes the American arsenal unique in that Washington has refused to bite the bullet and accept responsibility for the politically unpopular but nevertheless necessary decision to sustain the arsenal indefinitely.