Physicists Present Divergent Views on Need for Nuclear Weapon Design Competitions

On Jan. 12, the House Armed Services Committee’s Subcommittee on Strategic Forces held a hearing to receive testimony from the co-chairs of a recently completed National Academies study on peer review and design competition at the National Nuclear Security Administration (NNSA) national security laboratories: Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL), and Sandia National Laboratory (SNL). Although the hearing was very brief — just under 40 minutes long — it touched on issues with significant implications for the U.S. weapons science and engineering workforce and for U.S. nuclear weapons policy.

The study co-chairs were physicists Paul Peercy, Dean of the College of Engineering at the University of Wisconsin-Madison, and Jill Dahlburg Superintendent of the Space Science Division at the Naval Research Lab. Two other witnesses were unable to attend the hearing but submitted written testimony noting their disagreement with aspects of the panel’s recommendations: physicists Richard Garwin, an IBM Fellow Emeritus and a designer of the first hydrogen bomb, and Roy Schwitters, Professor of Physics at the University of Texas at Austin.

Subcommittee Chairman Mike Rogers (R-AL) began the hearing by highlighting the panel’s conclusion that “the state of peer review at the weapons labs is healthy and robust; the state of design competition is not.” After a set of questions examining the reasons underpinning the strong culture of peer review at the NNSA laboratories, representatives focused on the panel’s recommendation that the labs resume nuclear weapon design competitions primarily as a means of maintaining a skilled weapons design workforce.

Both Rogers and Subcommittee Ranking Member Jim Cooper (D-TN) identified workforce readiness as the fundamental basis of nuclear deterrence, with Rogers stating that “at its core, the credibility of our nuclear deterrent rests on the ability of our scientists and engineers to design, build, and field weapons in a timely way.” However, Cooper expressed concern about how other countries might react to the U.S. resuming design competitions and appeared skeptical of the need for full competitions to develop all the needed skills.

Proposed full design competitions would be first since ’92

The study panel notes that LANL and LLNL conducted more than 50 formal design competitions and over 1,000 nuclear explosion tests during the Cold War. However, since 1992, the U.S. has abided by a moratorium on explosive nuclear testing — although the U.S. Senate has not ratified the Comprehensive Nuclear-Test-Ban Treaty (CTBT) — and the labs have not conducted any formal design competitions. In place of this testing, the Department of Energy (DOE) created the Stockpile Stewardship Program (SSP) in 1995 to enhance understanding of the characteristics and aging of the nuclear weapons stockpile via computer simulations and experiments at new facilities. Despite initial doubts, the SSP has been a great success, endowing DOE with state-of-the-art facilities and supercomputing capabilities that enable the Secretary of Energy to certify the stockpile’s reliability with confidence.

However, the halting of nuclear testing and the transition to stockpile stewardship poses challenges for maintaining a skilled weapons design workforce, as most of the workers who participated in formal design competitions have either retired or could soon retire. Numerous studies over the past decade have drawn attention to the necessity and challenges of recruiting, retaining, and maintaining top talent at the NNSA laboratories, such as a 2008 Defense Science Board study on nuclear deterrence skills and a 2013 National Academies study on the quality of science and engineering at the NNSA laboratories.

One of the primary recommendations of the peer review and design competition study panel is that the best way to develop and maintain a skilled nuclear weapons workforce is to resume design competitions that include actual construction and testing of a non-nuclear prototype:

In the hearing, Dahlburg made an analogy to illustrate the role of design competitions, likening learning how to build a nuclear weapon with learning how to cook. She noted that having a recipe and watching video instructions does not fully substitute for hands-on experience, both in cooking and in nuclear weapons design.

The co-chairs asserted that the current warhead Life Extension Programs do not allow designers to employ all of the skills needed to maintain an effective nuclear deterrent especially given that other countries might attempt to build nuclear weapons with new capabilities. In particular, they advocate for “clean slate” competitions in which LANL and LLNL designers practice designing alternative nuclear explosive packages (NEPs) and SNL designers think through how to build the corresponding non-nuclear components using modern electronic systems.

Rogers noted that the National Defense Authorization Act for Fiscal Year 2016 directs DOE to establish a “Stockpile Responsiveness Program” to “continually exercise all capabilities required to conceptualize, study, design, develop, engineer, certify, produce, and deploy nuclear weapons.” Rogers asked the study co-chairs for their opinion of this provision, and Peercy responded that it is “very well aligned” with the panel’s recommendations.

Garwin and Schwitters criticize design competition proposal

In his initial round of questioning, Cooper began by probing whether there were any objections to the panel’s recommendations. The co-chairs noted that while the study panel was unanimous in its conclusions, some reviewers disagreed with aspects of the report. Earlier in the hearing, Cooper entered Garwin’s testimony and Schwitters’s testimony into the record as examples of scientists with alternate points of view. Although Cooper did not cite their testimony directly, he proceeded to raise objections similar to a few of those raised by the two physicists.

Cooper, Garwin, and Schwitters all pointed to potentially destabilizing effects of resuming design competitions. Cooper, for example, contended that “one element that was completely missing from the report is the State Department aspect because you’re kind of assuming that other nations won’t see this as a threat.” Schwitters acknowledged the need for weapons designers to develop and exercise their skills, but argued that

Similarly, Garwin acknowledged that design competitions could play an important role in refreshing the skills of weapons designers, pointing to his prior recognition of benefits of the Reliable Replacement Warhead (RRW) program. However, like Schwitters, he then argued that the study panel proposal does not provide enough details on the nature of the design competitions to assess their benefits and costs. Furthermore, Garwin argued that it is “rarely the case” that the U.S. would need to develop nuclear weapons with new capabilities to counter another country’s upgrades to its nuclear arsenal. He also pointed to labs’ nonproliferation and counter-terrorism work as alternate avenues for exercising design skills.

A simulating conversation

The role of simulated versus real-world experiments in the design process surfaced multiple times in the hearing. Both co-chairs asserted that limitations of computer simulations and incomplete understanding of weapon physics create the need for more real-world experiments, although stopping short of explosive nuclear tests.

Cooper reacted to this by highlighting the tension between the goals of performing realistic design competitions and the desire to not actually produce new weapons, asking “How do you make it real without it being real?” In her response, Dahlburg emphasized that “if you don’t actually compare your work with experimentation, you can delude yourself very easily… it’s our opinion that if we want to maintain [the workforce] for 30 years, we better have a little bit more hands-on experience.”

Nevertheless, after an exchange at the end of the hearing about the limitations of physics without experimental data, Cooper remarked “Well, you’ve confused me, but not being a physicist, I’m somewhat handicapped.”