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Integrated Codes

Integrated codes contain the mathematical descriptions of the physical processes relating to nuclear weapon systems and describe what the nation knows about how nuclear weapons function. This subprogram funds the critical skills needed to develop, maintain and interpret the results of the large‐scale integrated simulation codes that are needed for Stockpile Stewardship Program (SSP) maintenance, the Life Extension Programs (LEP), Significant Finding Investigation (SFI) resolution, and a host of related requirements, including transportation, dismantlements and forensics.


  • The ASC codes and computing infrastructure support DSW work such as design, analysis, baselining, and SFI resolution. Stockpile work, science and simulation are bound together through the Predictive Capability Framework (PCF).
  • In the context of simulation, predictive capability can best be understood in contrast to baseline models that were carefully calibrated to the underground test results and which employed sophisticated approaches to interpolation within the underground testing data or minimal extrapolation from tested regimes. As long as the calculated configurations were close to the as‐tested regime, one could be confident in the results. When life extensions and aging are also included, the simulations must be able to provide accurate results for weapon behavior away from the baseline.

Engineering and Physics Integrated Codes

This area delivers a suite of large-scale, integrated codes needed to support Stockpile Stewardship Program activities such as annual certification, life extension programs, and significant finding investigations. These codes include both classified and unclassified codes, codes used to simulate the safety, performance, and reliability of stockpile systems, codes used for the design and analysis of experiments, and codes to support analyses of weapons components and systems under normal, abnormal, and hostile environments. The codes are designed to run in parallel and make effective use of advanced ASC computing platforms.

Specialized Codes and Libraries

This area delivers both codes that have specialized function and libraries that are incorporated into integrated codes. Specialized codes have detailed physics focused on unique applications (e.g., radiation transport or ICF laser-plasma interactions) or are specific applications such as problem setup, meshing tools, and physics-based post-processing codes such as diagnostics tools. Libraries include mathematical solvers or physical database access routines.

Applications and Algorithms Research

This area is focused on research to investigate and develop algorithms, computational methods, and future physics, engineering, and numerical simulation technologies. This research enables advances toward greater predictive capability by focusing on overcoming critical obstacles in integrated codes (e.g., the need for robust and efficient solvers, design and optimization algorithms, and innovations that improve code effectiveness). Exploratory efforts include short-term focused research projects, as well as longer-term, more innovative efforts aimed at the large challenges.

Applications Research for Next-generation Platforms

This area is focused on research to investigate how the other areas within Integrated Codes will be able to exploit the next generation of platforms, including new technologies for massive parallelism both on-node (e.g., GPUs and large number of threads) and off-node (e.g., many nodes operating in parallel and new I/O technologies), as well as new programming models and resilient application codes.