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laboratories and U.S. Strategic Command to certify the safety and reliability of the U.S. nuclear weapons stockpile without additional nuclear testing. Although this experience is valuable for nuclear forensics, it is much more challenging to work from observations of unknown materials or from detonation debris from unknown devices and analyze and interpret them accurately and quickly. The nuclear forensics task is subject to the challenge of intense time pressure because of the demand for immediate answers. Additionally, in a domestic post-detonation event, the pressure for release of preliminary or partial analyses would be enormous.

In real-world interdiction cases and in exercises, U.S. laboratories have demonstrated the ability to analyze uranium and plutonium samples and report on the composition and time since last chemical separation of the material. In the same samples they can identify other materials and characteristic features of processes and features of facilities that might have produced the material in the sample. The laboratories have extensive experience with many other radioactive materials aside from uranium and plutonium, but most of that experience is not in conducting analyses needed for nuclear forensics, such as trace-constituent analyses and time since last separation. The laboratories are taking steps to improve their practices and methods to build greater confidence in the results. The timelines for obtaining results also vary depending on the material, the type of analysis, and the resources devoted to analysis and evaluation.

In addition to the incidents and domestic exercises, the national laboratories also take part in international round robin exercises that provide opportunities to compare analytic procedures and results. These international efforts complement the U.S. exercises and build relationships among the analysts, enhance development and application of techniques.

In post-detonation exercises, nuclear forensics has provided information sequentially about the nuclear explosive, beginning almost immediately and working to completion after receipt of samples at the national laboratories. For these exercises, the national laboratories were provided with advance notice and relatively good input data.

The timeline for post-detonation analysis and evaluation is longer than is desired. Even delivering on the exercised pace will be taxing to the limited human and facility resources that are available for this operation. It is the committee's judgment that under similar conditions the time required to provide all of the information with higher confidence than can be achieved today could be reduced with improvements in procedures and techniques.

These improvements include:

  • development and deployment of prompt diagnostic systems;

  • simulations to better interpret data from prompt diagnostics;

  • identification of useful short-lived signatures1 and how to measure them;

  • better planning for air and ground sampling;

  • development of tools and procedures for sample selection;

  • formalizing procedures for faster sample distribution to and receipt by fixed laboratories;

  • development of faster, more reliable sample-preparation techniques;

  • development of automated analytical techniques that meet modern environmental, health, and safety requirements;

  • simulations to explore signatures of nuclear-material-production technologies; and

  • more detailed simulations of the performance of a broad range of known and


Signatures are observable features that are indicative of the composition, origin, or history of the material or device.

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