ALBUQUERQUE, N.M. — After three years of intense work, Sandia National Laboratories has reached a key milestone in its efforts to modernize the B61 nuclear bomb – one of the oldest and most versatile weapons in the nation’s nuclear arsenal.
The bomb modernization program, which aims to extend the B61’s life another 20 years, is one of the biggest endeavors undertaken at Sandia since before the Cold War ended. The government is spending upwards of $8 billion on the project, part of a broad national effort to modernize most of the nation’s nuclear military complex during the next decade.
Sandia is working together with Los Alamos National Laboratory and the U.S. Air Force on upgrading the bomb, with the first newly refurbished B61s projected to roll off the assembly line by March 2020. Lab leaders say the project is on schedule and, at least for now, under budget.
Sandia conducted a weeklong wind tunnel test in February to measure the B61’s aerodynamic performance at the speed of sound. That provided the first opportunity to collect comprehensive data on how a newly built tail kit assembly interacts with other components on the bomb, said James Handrock, director of Sandia’s nuclear weapons systems engineering. That, in turn, will help push the project closer to a planned, real-flight test next year at the Tonopah Test Range in Nevada.
The new tail kit assembly is important because it adds a guidance system to the bomb, basically converting it from a gravity-dependent dumb bomb into a smart one that can be aimed more precisely at a target.
“We developed the preliminary design … and the wind tunnel test allowed us to try that out to see what adjustments may still be needed,” Handrock told the Journal. “It all has to work smoothly together. We need to make sure the baseline design is what we will use in the upcoming flight tests.”
The test provided the performance measurements needed to guide the next stages of design work, he said.
Critics question the cost of the overall modernization plan, which has skyrocketed from an estimated $4 billion in 2010 to at least $8 billion today. They also fear the new tail kit guidance system, along with other modifications, add new capabilities to the weapon, potentially undermining the government’s declared policy of simply extending the life of nuclear arms without creating new ones.
Sandia is working on upgrades to three nuclear warheads: modernization of the B61, modifications to aging components in the W88 missile designed for submarine launch and the ground-launched Mk21 intercontinental cruise missile.
About 1,000 Sandia employees are working on the projects, which together have an estimated annual budget of more than $1.2 billion through the end of this decade, according to Sandia President and Director Paul Hommert.
But the B61 is, by far, the biggest since it involves a complete overhaul of nearly all weapon components. About 600 employees are working on it, and Congress approved $537 million this year for combined work on the project at Sandia and LANL.
“We’re modernizing all components of it, including all the electronics and safety mechanisms and different delivery systems,” Hommert told the Albuquerque Economic Forum in April. “It’s the largest effort of this type in over 30 years.”
The project will consolidate four different B61 models developed during the Cold War into a single weapon called the B61-12.
Apart from requalifying and remanufacturing existing components, the project calls for redesign of many parts, such as safety features, plus the addition of new things like the tail kit assembly.
All current B61 models are gravity bombs dropped over targets. They don’t have flight-guidance systems that could pinpoint them for greater accuracy once released.
In addition, the bomb could be programmed to carry a lower yield to destroy specific targets, thus reducing radioactive fallout and lowering potential for collateral damage.
The Boeing Co. is building the guided tail kit under contract with the Air Force, and Sandia is working on the overall bomb redesign to integrate it into the weapon.
The wind tunnel test in February allowed engineers to see for the first time how the tail kit interacts with the overall bomb design. That’s a critical step before moving to real flights, because engineers must make sure the tail kit contributes smoothly to the bomb’s spin motion during freefall.
Spin motion is needed to stabilize the bomb as it glides toward its target. It’s controlled by rocket motors and slanted fin tails. But in earlier B61 designs, air plumes from the motors have interfered with fin performance, thus weakening the push, or torque, created by the motors and reducing spin rates.
“We needed to test and characterize that aerodynamic performance with the new tail kit,” said Chris O’Gorman, manager of the B61-12 technology basis department.
To conduct the test at full scale, Sandia went to Arnold Air Force Base in Tennessee, which operates the nation’s largest wind tunnel capable of producing required acceleration beyond the speed of sound. The new bomb design was tested continuously there for eight days, after three years of preparatory design and engineering work.
About 75 percent of the basic B61 redesign is complete, and the lab expects to reach 95 percent before the first planned test flight in Nevada next year, according to Hommert.
Still, as modernization moves forward, nuclear watchdog organizations are critical of the project’s total costs, and of the redesign plans.
“Its been very contentious,” said Hans Kristensen, a nuclear weapons analyst at the Federation of American Scientists in Washington, D.C. “The National Nuclear Security Administration estimated about $4 billion originally in 2010, and then in 2012 that ballooned to $8 billion. The new tail kit assembly alone could cost up to $1.5 billion.”
In fact, the U.S. Department of Defense now estimates total B61-12 program costs at $10.4 billion. With about 400 B61 bombs to be refurbished, that’s about $25 million per bomb, Kristensen said.
Jeffrey Lewis, nuclear policy analyst at the Monterrey Institute in California, said taxpayers could get a lot more bang for the buck if the NNSA scaled back its “Cadillac approach” to modernization by instead doing some key modifications and not a comprehensive redesign.
“It’s like they want to be locked into the most expensive plan,” Lewis said. “I’d like to see more compromising solutions.”
Given the bomb’s substantial redesign, particularly the new guided tail kit, the program might go beyond current federal policy of simply extending the life of existing weapons, Kristensen added.
“This is the first real nuclear weapon bomb program after the Cold War that’s adding significant new capabilities,” Kristensen said. “It raises the question, is the U.S. back in the nuclear bomb business?”
Advocates, however, say that by consolidating four old B61 models into one newly designed B61-12, the program is cutting modernization costs, while reducing the total number of bombs in the arsenal.
In addition, Hommert said efficient management is helping to cut project expenses, with a projected $120 million in cost savings over the life of the program.
“People thought we couldn’t staff the B61-12 program and hold costs down,” Hommert said. “But we’re managing to stay under budget and on schedule.”