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Prospects Grow for Cuts to U.S. Nuclear "Hedge Force"
WASHINGTON -- The U.S. government could reduce its stockpile of backup nuclear weapons in coming years as the capability improves to swap out aging components in active warheads for fresh parts, according to a senior military official (see GSN, March 1, 2010).
The nation's nuclear complex is adopting this new approach -- called "component sparing" -- as an eventual alternative to maintaining today's "hedge force," said the official, who requested anonymity in discussing sensitive nuclear-weapon issues.
Already used widely in the commercial world, component sparing allows defective or corroded nuclear systems to be refurbished by installing new or reused parts.
Although the nuclear complex already employs component sparing to some degree, officials anticipate they will come to rely more heavily on the process in the future, decreasing their reliance on using fully assembled warheads to replace non-functioning weapons.
The Pentagon currently holds roughly 2,290 strategic nuclear warheads in reserve, according to issue expert Hans Kristensen. That constitutes a hedge force of more than one fully assembled backup warhead for each of the 1,950 strategic warheads deployed at bomber aircraft bases, on ICBMs or on submarine-launched ballistic missiles, he said.
Another 3,300 or so warheads have been retired from military service and transferred to the Energy Department for eventual dismantlement, said Kristensen, who directs the Nuclear Information Project at the Federation of American Scientists.
Dismantlement is a painstaking and labor-intensive process, leaving the Energy Department with a considerable backlog. The Pantex facility in Texas disassembles less than 400 warheads each year, and even with anticipated upticks in the rate of elimination, warheads retired by 2009 will not all be dismantled until 2022, Kristensen said.
Any subsequently retired weapons are expected to enter the disposal queue after that, he said.
Meanwhile, hedge warheads that remain actively maintained could be deployed in the event that defects are discovered in deployed systems or, perhaps less likely, to expand the U.S. arsenal if a significant global threat emerges.
"There's nothing in industry that does business that way any more," the senior official said in an interview last month. "What you do is you have variety in the weapon component, so you do component sparing."
Introducing the new approach into the nuclear complex and whittling down the hedge force is something like a "30-year project," the senior official noted. "But we're on the path to do that, because that's how you drive down the inventory."
To offset the possibility that a backup warhead component might share the same defect discovered in a weapon in the deployed arsenal, each type of warhead in the U.S. force should be capable of accepting parts that use alternative designs, the official said.
"So if you've got a component -- [such as] a fuse -- I've got two fuses in the inventory that can work there," the military leader said. "I don't have two bombs; I have two fuses. And I get my diversity and hedge in the diversity at the component level, not the end-item level."
This so-called "component diversity" could be especially important as Washington reduces the number of nuclear warheads it retains in the arsenal and consolidates the stockpile into fewer warhead designs (see GSN, Dec. 24, 2009).
Under the New START accord, which entered into force this year, Russia and the United States agreed to cap each side's deployed warheads at 1,550 and fielded delivery vehicles at 700. The Obama administration has said the Defense Department is now studying the prospects for additional reductions below the ceiling set by the treaty.
The Pentagon said in its 2010 Nuclear Posture Review that it would consider the possibility of developing a set of components to extend the service life of an Air Force Minuteman 3 ICBM warhead, called the W-78, that could also be used "on multiple platforms in order to reduce the number of warhead types."
Specifically, the Pentagon is looking to develop a joint Air Force-Navy modernization approach in which the Minuteman's W-78 warhead and the Trident D-5 submarine-launched ballistic missile warhead, the W-88, would share the same life-extension package, a senior Air Force official told Global Security Newswire in 2009.
In the joint effort, recently approved by the Defense secretary's office, the Navy is "working the adaptable arming, fusing, firing circuit package for the [W-]88 which will be applicable to the [W-]78, and potentially other Air Force weapons," Rear Adm. Terry Benedict, who directs Navy Strategic Systems Programs, said at a Capitol Hill event in June.
To reduce the risk that a single catastrophic flaw could make all the warheads obsolete in an entire leg of the nuclear triad, each service would also likely retain a second warhead design deployed on a portion of its ballistic missiles.
The Air Force now fields 200 W-87 warheads on its Minuteman fleet, with the W-78 filling out the remaining 250 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.
However, in a further bit of consolidation in warhead design, the W-78 is to receive the primary explosive package from the alternative Minuteman 3 warhead, the W-87, when it undergoes refurbishment, according to Lisbeth Gronlund and Stephen Young of the Union of Concerned Scientists.
After the combined life-extension effort is complete, the nation's future ballistic missiles might include a mix of: SLBM and ICBM warheads that have received the joint life-extension components; a separate Navy-only warhead; and a separate Air Force-only warhead. Gravity bombs and cruise missiles would almost certainly remain in the arsenal with markedly different warhead designs, officials have said.
The Nuclear Posture Review -- which assessed the nation's atomic weapons strategy, forces and readiness -- stated that as the United States consolidates its nuclear arsenal, Washington would "consider reductions in nondeployed nuclear weapons, as well as acceleration of the pace of nuclear warhead dismantlement."
The approach has enjoyed some political support, but has also drawn barbs from both liberals and conservatives.
Roger Logan, the former head of Directed Stockpile Work at the Lawrence Livermore National Laboratory in California, applauded the emerging spare-parts process but said implementation should have begun years earlier.
"Tens of billions of dollars" could have been saved if the effort to ensure component diversity had been launched more than 12 years ago, when it was first proposed by scientists and engineers, he said.
"For expensive components like arming and fusing [mechanisms], if you can keep those extra components on hand, and keep them with test-proven interchangeability, you can cut down on ... inventory -- the number of complete warheads you have to keep around," he told GSN last week. "It is still a good idea."
"It is a better strategy to create a component hedge than a warhead hedge because it will make reductions in the hedge [force] easier in the future," agreed Kristensen.
That is exactly the focus of concern, though, in some quarters of Capitol Hill.
The House in May passed defense authorization legislation, called H.R. 1540, that would restrict the Obama administration's ability to cut deployed or nondeployed nuclear weapons below levels set by the New START accord, unless required by a treaty or authorized by Congress.
Under certain conditions, the House measure could also prohibit the executive branch from eliminating weapons in the hedge force until the mid-2020s, when a new plutonium facility being constructed at the Los Alamos National Laboratory in New Mexico and a uranium plant at Oak Ridge, Tenn., are scheduled to be up and running (see GSN, May 27).
The two new facilities are expected to be instrumental in preserving a U.S. capability to process nuclear materials for the weapons arsenal for years to come.
The White House in May issued a "Statement of Administration Policy" asserting that the House legislative initiative "would set onerous conditions on the administration's ability to implement the treaty, as well as to retire, dismantle or eliminate nondeployed nuclear weapons."
The Senate Armed Services Committee in June passed a less-stringent measure that would require the White House to submit to Congress a "net assessment" to support any new proposal "to reduce the nuclear weapons stockpile below the numbers in the New START treaty or to reduce the number of hedge weapons in the stockpile," the panel said in a public release (see GSN, June 22).
The reason for lawmaker concern about reducing the reserve force "is obvious," Senator Jon Kyl (R-Ariz.) told reporters in May. "Until you have the capability of reproducing the warheads, you don't want to eliminate the hedge that you have" (see GSN, May 10).
The senior military official acknowledged that the new nuclear materials processing facilities set for construction should help ensure the ability to maintain a viable U.S. arsenal. He also noted that it would take decades before warheads retired today could actually be dismantled.
"The fear is," though, that lawmakers will say, "'Don't get rid of anything in the hedge [force].' That really ties our hands," the senior official said. "It drives costs way, way up -- keeping something that you have no intent of using."
As designs are consolidated and the practice of component sparing increases, the administration sees potential cost savings and security benefits in reducing the size of the hedge force, said the official, who declined to provide specific figures.
"There were some [warhead-retirement projects] that were blessed a long time ago and which we are just finishing up and cleaning out. It takes multiple years to do them," the senior figure told GSN. "There are others that we could start to do now."
Some warheads new to the retirement to-do list are associated with the seven-year time frame that Washington and Moscow have set for completing their New START reductions, the official said.
The treaty does not directly require any warhead dismantlement, but excess ICBM and sea-launched ballistic missile warheads under the accord could be taken out of the Defense Department stockpile and eventually disassembled, Kristensen said.
Others "could be done as part of a hedging strategy that went to the component level," the U.S. official added. If, for example, roughly 60 percent of the components in a given warhead type have been replaced, "I might be able to get rid of a whole bunch of end-items but keep components," the leader explained.
Many warheads are dismantled with the aim of cannibalizing parts for other warheads that will remain part of the active and deployed arsenal, Kristensen said. A steep reduction in the quantity of deployed Trident submarine-launched W-76 warheads over the past several years, for instance, has freed up more than 1,000 of the weapons to be used as potential sources of spare parts, and several hundred more such weapons are to be retired in the years to come, he said.
Defense and Energy officials run the risk of taking the component-sparing concept too far, though, according to some critics.
"The mixing and matching of components must not undermine confidence in the reliability of the existing warheads by modifying them further from the designs that were tested," Kristensen said.
He contested a growing view among national laboratory leaders and executive branch officials that components from one nuclear explosive package could be safely paired with components from a different nuclear explosive package, even if the new combination has never been subjected together to underground testing.
The United States has honored a moratorium on nuclear explosive testing since the early 1990s.
Increased confidence in a mix-and-match approach to component sparing is justified by technological advances and deeper understanding of the nuclear stockpile developed over the past few years through such tools as nonexplosive tests, computer analyses and simulations, in the view of some government officials (see GSN, June 16, 2010).
Logan takes issue with a permissive approach to new combinations of nuclear weapon parts. He said component sparing is useful only for nuclear explosive parts that were tested together before the moratorium began, or for non-nuclear parts -- such as arming, fusing or gas-transfer system components -- that can still be tested today without an atomic detonation.
"You can mix and match many non-nuclear components ... as long as they are tested together in the new configuration and as long as they don't interfere with the nuclear-yield package," Logan said. "We have done this for decades."
However, he said, "nuclear package components -- those that can only be function-tested with nuclear tests -- cannot be mix-and-match swapped."
Today's nuclear weapons, according to the senior military official, are a far cry from the designs that were explosively tested before the last U.S. underground trial took place in 1992.
"There is no configuration that's the same as we tested. That's long gone," the official said. "There are components that have been through [testing]. The mixing and matching of those components, we understand well enough to do."
Logan said that the nation has "a good nuclear test base" off of which the nuclear complex can continue to draw vital data.
In the event that a particular warhead component becomes dysfunctional and no appropriately tested replacement is readily available, the Energy Department should initiate new production of an old component design that was earlier tested with that weapon, he said.
Introducing a different part into the weapon for the first time would increase the risk that the warhead would no longer function if it is ever needed in conflict, and thus could undermine confidence in peacetime, Logan said.
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A fact sheet on current and projected costs of maintaining the U.S. nuclear deterrent, produced by the Center for Nonproliferation Studies.
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The submarine proliferation resource collection is designed to highlight global trends in the sale and acquisition of diesel- and nuclear-powered submarines. It is structured on a country-by-country basis, with each country profile consisting of information on capabilities, imports and exports.