Pentagon Eyes Shared Modernization Package for Navy, Air Force Warheads

(Dec. 24) -A U.S. Ohio-class submarine launches a Trident D-5 missile. The Defense Department might opt to extend the service life of one Trident D-5 nuclear warhead, the W-88, in a joint Navy-Air Force effort also aimed at updating the W-78 warhead, used on Minuteman 3 ICBMs (Getty Images).
(Dec. 24) -A U.S. Ohio-class submarine launches a Trident D-5 missile. The Defense Department might opt to extend the service life of one Trident D-5 nuclear warhead, the W-88, in a joint Navy-Air Force effort also aimed at updating the W-78 warhead, used on Minuteman 3 ICBMs (Getty Images).

WASHINGTON -- The U.S. Defense Department is exploring how it might devise a single nuclear warhead modernization package that could be used for updating different weapons in both the Navy and Air Force arsenals, according to a senior official (see GSN, Nov. 20).

The Obama administration's Nuclear Posture Review -- a major assessment of atomic strategy, forces and readiness due to Congress by February -- might include such a joint-service, warhead life-extension effort as one of its key recommendations, defense officials tell Global Security Newswire.

Under the proposed approach, aging components in the explosive portion of distinct nuclear warheads might be swapped out for a standardized set of more modern replacement parts, said Billy Mullins, the Air Force associate assistant chief of staff for strategic deterrence and nuclear integration.

Most of the roughly 2,200 warheads deployed in the U.S. strategic nuclear stockpile are several decades old. Under this modernization scheme, many of the replacement pieces used to modernize the weapons would be spare parts or components taken from retired or disassembled arms that are now available for reuse, Mullins said in a Dec. 11 interview.

The Air Force and Navy, which control the nation's nuclear-armed missiles and bombs in peacetime, typically have undertaken separate life-extension programs -- or "LEPs" -- to enable aging nuclear warheads to remain viable for years to come.

For example, along with the Energy Department, the Navy is extending the service life of the W-76, a warhead deployed on its Trident D-5 submarine-launched ballistic missile (see GSN, Nov. 6). Meanwhile, Air Force and Energy officials are in the initial stages of planning an update for some versions of the B-61 gravity bomb (see GSN, Aug. 13).

The objective of initiating a joint Navy-Air Force life-extension program would be to ultimately reduce the costs of maintaining warheads across the two services by minimizing the number of unique parts they incorporate, Mullins said. If instead they had more components in common, replacement parts and labor to fix or maintain them could cost less, the theory goes.

Total cost estimates for sustaining nuclear warheads are difficult to find, but experts have said the investments are minimal compared to maintaining and operating the missiles and aircraft on which the warheads would be delivered (see GSN, Oct. 30, 2007).

However, Mullins indicated that costs and prospective ease of maintenance appear to be driving the current discussion.

"We've had joint warheads in the past, but we've built them from the start as a joint warhead," he said, referring to cruise missile and gravity bomb designs the two services have shared. "And so now we're saying, 'Well, how much jointness can we do if we did an LEP, and tried to share as much componentry -- as much piece parts -- [as possible] between the two services?'"

Defense Secretary Robert Gates and his aides have not yet made a decision but are "discussing it with the Air Force and Navy," Mullins said.

If the Nuclear Posture Review endorses the approach, an initial study to explore exactly what a joint project would entail could begin as early as this fiscal year, he said.

A basic "concept assessment" could be launched in 2010 or, alternatively, the effort might begin with a more carefully detailed "feasibility study" in fiscal 2011. Mullins would not say whether funds for the effort are anticipated for inclusion in President Barack Obama's budget request for the next fiscal year, which is due Feb. 1 on Capitol Hill.

Warheads that might be part of a joint LEP effort would likely be limited to those for ballistic missiles, a delivery platform that both the Air Force and Navy field in their respective fleets.

Weapons due to receive life extensions in the coming years, Mullins said, include the W-78, which goes aboard Air Force Minuteman 3 ICBMs, and the W-88, which the Navy uses on its Trident D-5 submarine-launched ballistic missiles. Other ICBM and SLBM warheads either were recently updated or are already undergoing single-service life extension programs, he noted.

These two ballistic missile warheads use different design blueprints, so only a limited number of components could be shared, the Air Force official said.

"A ballistic missile warhead coming in at Mach 20 is pretty delicate in its flight dynamics," so officials must avoid potential temptations to force particular replacement parts to fit, Mullins said.

"While there may be 20,000 piece parts at Pantex, you might find that it's only a handful that could fit in the right place with the right mass properties so that those [missile re-entry vehicles] fly right," he said, referring to the facility in northwest Texas where nuclear warheads are maintained, stored and dismantled.

A senior defense official first raised the idea of injecting "common design elements" into Air Force and Navy warheads during an August interview with GSN. The eventual goal might be to begin consolidating the nuclear arsenal into fewer designs as force levels shrink under arms control reductions.

"In the future, we may not always have different warheads for our ICBMs and our SLBMs, in particular," said the official, who spoke on condition of anonymity because of political sensitivities surrounding the ongoing Nuclear Posture Review (see GSN, Aug. 27).

Such an approach, the official said, "would involve mixing and matching primaries and secondaries" -- the two explosive stages of a thermonuclear weapon -- that were proven functional in past experiments. The United States has observed an informal moratorium on underground nuclear tests since the early 1990s.

Even if the Obama administration embraces a joint approach to modernizing the Minuteman's W-78 warhead and the Trident's W-88 warhead, each service is expected to also retain a second warhead design deployed on a portion of its ballistic missiles, Mullins said.

Specifically, the Air Force now fields 200 W-87 warheads on its Minuteman fleet, with the W-78 filling out the remaining 350 fielded warheads aboard a total of 450 land-based missiles. For its part, the Navy deploys a mix of 768 W-76 warheads and 384 W-88 warheads aboard its 288 Trident D-5 submarine-launched ballistic missiles, according to recently compiled data.

This diversity helps ensure that a potential catastrophic failure in one type of warhead would not affect the viability of other U.S. warheads, a risk that scientists term a "single-point failure."

After a combined LEP effort is complete, the nation's future ballistic missiles might include a mix of: SLBM and ICBM warheads that have received the joint LEP components; a separate Navy-only warhead; and a separate Air Force-only warhead, Mullins said.

In addition, gravity bombs and cruise missiles would almost certainly remain in the arsenal with markedly different warhead designs, Mullins said.

Eventually, he said, the Pentagon might opt to winnow the number of distinct warhead designs in the U.S. arsenal from the current dozen or so down to just a handful. A future U.S. arsenal might be composed of roughly five different warheads -- three warhead types on the ballistic missiles, one on gravity bombs and one on cruise missiles, Mullins speculated.

"It's sufficiently diverse and it addresses [the risk of] a single-point failure," Mullins said.

He did not offer a time frame for when this concept for consolidation and life extensions could be completed across the nation's entire stockpile, but government estimates for modernizing the force have typically involved several decades of work.

A joint LEP approach would diverge from Bush administration plans for warhead modernization, the Air Force official noted. Under former President George W. Bush, defense and energy officials had proposed building a new series of "Reliable Replacement Warhead" designs that could eventually supplant all weapons in the U.S. nuclear fleet.

The aim was to field weapons that could be safer, more secure, easier to sustain and more reliable than the aging warheads they replaced.

However, Congress repeatedly denied funds to develop an RRW program. Lawmakers argued that building a new-design warhead could undermine Washington's efforts to generate global support for preventing Iran, North Korea and other nations from building weapons of their own (see GSN, Sept. 24).

Inside the Obama administration, top officials have been divided over how to keep the U.S. arsenal safe and reliable while pursuing a White House vision for global nuclear disarmament -- dual objectives that the president laid out in Prague last April (see GSN, Aug. 18).

Although reusing previously tested warhead components was a facet of the RRW effort, Mullins said a joint LEP project would differ with the canceled program in at least one significant respect.

"Where RRW differed from an LEP is there was going to be a new pit," said Mullins, referring to the explosive core of a weapon. "We're not talking [about] that in a joint LEP. This is not a new pit."

"Reusing components from different warheads" is an "excellent idea" that "has taken hold within government and laboratory circles as a potentially valuable form of life extension," said Linton Brooks, who served as administrator of the Energy Department's semiautonomous nuclear arm from 2003 to 2007. "It potentially allows for a more robust form of life extension without the political and financial drawbacks of designing and developing new components."

Though there may be "potential advantages to common components" across the Navy and Air Force weapon systems, Brooks told GSN this week that he was unfamiliar with the specific proposals under consideration.

One former Pentagon policy official in the prior administration said he, too, was unaware of the details involved in building additional warhead commonality, but warned that such an approach might offer only limited benefits.

"If this proposal can avoid having to negotiate the imprecise issue of 'whether or not something is new' and if this helps maintain the stockpile, I for one will applaud," said Thomas Scheber, vice president of the National Institute for Public Policy. "However, as Americans we should recognize that not doing anything new guarantees eventual obsolescence. We have imposed unofficial burdensome policy constraints on ourselves."

He suggested that existing warhead designs could be expected to withstand aging and meet the test of new security threats for only so long.

"Reuse of off-the-shelf components would use existing (not new) parts in warheads carried by existing (not new) weapons for the same types of missions (not new) as at present," Scheber told GSN in an e-mailed response to questions. "Whether this is just following a path of least resistance or a brilliant idea remains to be seen."

Stephen Young, a senior analyst at the Union of Concerned Scientists, was also skeptical of the proposed effort, but for very different reasons.

"In terms of keeping the U.S arsenal safe, the mantra should be much like a doctor's: First, do no harm," he said, noting the risks involved in using slightly different components that could make a warhead malfunction. "Too often, seemingly reasonable but unproven conjectures -- like the simplicity and value of reusing components -- are asserted as fact when they are not."

Young said the proposal deserves "further study," but the Obama administration in the meantime should stick with "what we already know works: our existing life-extension programs."

Last month, GSN was the first to report that a top scientific advisory panel had determined that periodic life-extension efforts would remain a viable means of keeping the U.S. arsenal safe and effective into the future (see GSN, Nov. 9).

The JASON expert group had previously found that a replacement-warhead approach could introduce unnecessary risk of weapon failure in the absence of explosive testing (see GSN, Oct. 1, 2007).

In light of the JASON conclusions, any alternatives to the typical life-extension approach, "including proposals to swap components between warheads, need to be extensively evaluated before they are introduced into the arsenal," Young said.

December 24, 2009

WASHINGTON -- The U.S. Defense Department is exploring how it might devise a single nuclear warhead modernization package that could be used for updating different weapons in both the Navy and Air Force arsenals, according to a senior official (see GSN, Nov. 20).