Office of Stockpile Stewardship

Mission

The Office of Stockpile Stewardship directs research, development, computer simulation, and inertial confinement fusion activities to maintain the safety, security and effectiveness of the nuclear weapons stockpile; provides a technical basis for the annual assessment; develops modernization options, such as multipoint safety; and quantifies and mitigates the effects of aging on the stockpile. The combination of experimental and computational programs represent the nation’s modern alternative to underground testing, ensuring a safe, secure, and effective stockpile while supporting the nation’s arms controls and nonproliferation commitments. The organization also serves as a liaison with the Department of Defense on nuclear weapons matters, including the Annual Certification process; coordinating with NNSA’s international partners on scientific issues; and providing technical support for treaties regarding U.S. science, technology and engineering capabilities and transparency options.

The Nation’s nuclear deterrent remains a vital part of our national security infrastructure. It maintains strategic stability, deters potential adversaries, and reassures our allies and partners of our security commitments. Maintaining a stockpile [1] of nuclear weapons that friend and foe alike recognize as second to none requires the best science and technology, particularly in this post nuclear testing era.

Since 1992, the United States has observed the moratorium on underground nuclear testing while significantly decreasing the total nuclear arsenal. While this important achievement has allowed the country to pursue a variety of nonproliferation and disarmament goals, it has also required NNSA and its weapons laboratories to replace the functions of nuclear tests with the science-based Stockpile Stewardship Program [2] to ensure the safety, security and effectiveness of the stockpile. The SSP combines nonnuclear experiments, highly accurate physics modeling, and improved computational power to simulate and predict nuclear weapon performance over a wide range of conditions and scenarios. This predictive power affords NNSA and the weapons laboratories the necessary tools to assess the stockpile, maintain its performance, continuously improve safety, respond to technological surprise and support future treaties. The office is comprised of the following Programs:

These three offices work together to comprehensively support the stockpile. Experiments extend and validate the computational models [6] that are the basis for designing and evaluating new technologies or manufacturing approaches and resolving questions related to aging. Implementing these challenging programs maintains a workforce at the cutting edge of weapons physics issues, and a talented and energized workforce is the foundation of stockpile maintenance over the long term. Among our ongoing efforts are the following activities:

Providing a thermonuclear ignition platform at the National Ignition Facility (NIF) to investigate physics associated with weapons effects, radiation transport, secondary implosion, and ignition at extremes of temperatures and pressures that are achievable only on the NIF;
Developing first-principle’s physics models to replace empirical parameters—aspects of weapons performance determined through testing and applicable only to a specific system—for advanced modeling of weapons performance;
Conducting key experiments and modeling to inform the advanced certification, safety, and security of our stockpile and complete proof-of-concept work on at least two new, intrinsic, multi-point safety options;
Providing a suite of world-class high energy density physics user facilities to explore weapons physics that otherwise occur only in celestial bodies;
Planning and preparing for steps beyond ignition; and
Building academic alliances to ensure a continuous pipeline of preeminent scientific and engineering talent to the national laboratories.

All of these efforts represent a great scientific challenge coupled with a challenging timeline that we manage and meet through the Predictive Capability Framework [7](PCF). The PCF is a long-term integrated roadmap to guide the science, technology and engineering activities and Directed Stockpile Work to the highest priority needs of the nuclear stockpile and its continuing certification.

Air-gas breakdown when Z Machine at Sandia National Laboratories fires

Forty-eight final optic assemblies are symmetrically distributed around the upper and lower hemispheres of the target chamber (National Ignition Facility, Lawrence Livermore National Laboratory)

OMEGA EP laser beams during a test shot with all four beams firing (University of Rochester Laboratory for Laser Energetics)

The Texas Petawatt laser bay at the University of Texas, Center for High Intensity Laser Science (Stockpile Stewardship Academic Alliance Program)

Natalia Zaitseva, a Lawrence Livermore National Laboratory (LLNL) materials scientist, leads a team of LLNL researchers that has developed the first plastic material capable of efficiently distinguishing neutrons from gamma rays, something not thought possible for the past five decades or so.

NNSA Advanced Simulation and Computing (ASC) Program Cielo computing system (Los Alamos National Laboratory).