In my last post, I talked about the origins of the Stockpile Stewardship and briefly described the three activities which make up stockpile stewardship: stockpile science, stockpile surveillance and warhead life extension. In this post, Id like to discuss the challenge of life extension in greater detail, and show how this challenge has motivated the debate over the Reliable Replacement Warhead program (RRW).The goal of the life extension programs (LEP) is to add anywhere from 20 to 30 years onto the (nominal) design lifetimes of the various warhead models in the stockpile (of course, "there is no such thing as a 'design life'"...). The W87 ICBM warhead became the first warhead to complete its LEP in 2004. The B61 bomb warhead and the W76 SLBM warhead the first warhead slated for replacement under RRW are currently undergoing LEPs, while the W80 cruise-missile warheads LEP was recently canceled by the Nuclear Weapons Council in order to free up funds for RRW.A life extension program is a sort of 50,000-mile tune-up for a nuclear warhead: limited-lifetime components such as batteries and neutron generators are replaced, along with any other parts "cables, elastomers, valves, pads, foam supports, telemetries, and miscellaneous parts" which may have degraded. Most of these replacements take place outside the warheads nuclear explosives package, however.While these tasks sound mundane, manufacturing the replacement components is no mean task. Manufacturing lines still exist for some components, but in other cases, lines have been dismantled, suppliers have canceled product lines or gone out of business, and health, safety and environmental regulations have grown stricter.In these cases, a dilemma arises: should the nuclear production complex go to extreme lengths to recreate the processes needed to remanufacture these components exactly according to the original specifications? Or should they look for ways to make replacement parts that will work just as well, if not better? Since the part has to be replaced anyway, why not make maintenance easier for future generations already?For components outside the warheads' nuclear explosives package, modifying the manufacturing specs is an attractive option, since each new component can be tested exhaustively without underground nuclear testing.If too many of these minor changes pile up, though, a sort of "Grandfathers axe" effect may kick in: if enough components have been modified and replaced, is the warhead design still the same one that was once tested? For this reason, the guiding philosophy has been "change-control discipline": make the fewest number of changes possible, and only after proving exhaustively that the changes will not affect warhead characteristics.For nuclear components, the problem is more serious. While there are ways to investigate how a nuclear component will behave when detonated computer simulations which model the component, dynamic and quasi-static experiments which measure its relevant physical properties, sub-critical experiments which assess its behavior under conditions similar to actual detonation none of these methods has the same doubt-erasing effect as an underground nuclear test.Any modification to proven designs for nuclear components is therefore bound to cause anxiety as long as underground nuclear testing is forbidden.Conceptually, this is where the Reliable Replacement Warhead program (RRW) enters the picture.
While some members of the stockpile policy community argue that something like change-control discipline can be applied to nuclear components, too, others believe that if any modification is going to be made to the nuclear explosives package, a broader set of changes has to be made to the warhead design try to offset any possible drop in the performance of those modified components.In brief, the changes being contemplated by those in the latter camp would increase the performance margins of warhead designs. The performance margin is the difference between the energy which the primary stage is expected to produce and the minimum energy needed to set off the secondary stage essentially, the warhead's margin of error.Since increasing the performance margin would require modifications to warhead designs that go well beyond what change-control discipline would allow, it would require an entirely new philosophy of stockpile stewardship. This philosophy is to be put into practice through a program known as Reliable Replacement Warhead.RRW was introduced into the fiscal year 2005 Department of Energy budget by Rep. David Hobson, R-Ohio, the chairman of the House Appropriations Committee's Energy and Water Subcommittee. Hobson, a noted budget hawk, believed that the Bush Administrations latest nuclear weapons program, the Robust Nuclear Earth Penetrator (RNEP) or "nuclear bunker buster" would be both costly and unnecessary, not to mention harmful to the nations non-proliferation posture. His committee therefore cut all funds for RNEP, and allocated the funds instead to a "program to improve the reliability [and] longevity... of existing weapons and their components" and RRW was born.Almost immediately, rumors began to circulate that the Department of Defense intended to use RRW as an opportunity to expand the capabilities of the U.S. nuclear arsenal to work around the cancellation of RNEP. These rumors led Hobson, in March 2006, to complain that "sometimes within the [DOE], people hear only what they want to hear," and remind NNSA head Linton Brooks that "this is not an opportunity to run off and develop a whole bunch of new capabilities and new weapons."Even today, though, Brooks continues to advertise RRW as an "enabler" for the transition to a "responsive infrastructure" which will one day "provide capabilities, if required, to produce weapons with different or modified military capabilities". And the official DOD website on "Stockpile Transformation" (the generic name for RRW and related plans) boasts of a goal of "develop[ing] warheads for next-generation delivery systems" seemingly a direct contradiction of Hobsons injunction.This ongoing back-and-forth about RRWs purpose inspired the Congressional Research Services comment, quoted in my earlier post, that "many find RRW to be confusing."In the third post, I will discuss the changes which are being made to the warheads' nuclear components, and examine the debate over whether or not those changes require a wider set of modifications to the warhead designs and therefore RRW.- Haninah Levine