Nuclear data covariances are critical input to determine upper sub-critical limits and to design experiments to increase it [Slides]

Conference · Tue Oct 11 00:00:00 EDT 2022

DOI:https://doi.org/10.2172/1894822· OSTI ID:1894822

Little, Robert Currier  ^[1]; Rising, Michael Evan  ^[1]; Alwin, Jennifer Louise  ^[1]; Bahran, Rian Mustafa ^[1]; Grove, Travis Justin ^[1]; Clark, Alexander Rich  ^[1]; Hutchinson, Jesson D.  ^[1]; MacQuigg, Michael Robert ^[1]; McSpaden, Alexander Thomas  ^[1]; Michaud, Isaac James  ^[1]; Riedel, Bobbi ^[1]; Smith, Travis Austin  ^[1]; Thompson, Nicholas William  ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

This presentation discusses how Upper Subcritical Limits (USL) are key parameters to determine operational limits in nuclear criticality safety evaluations. It also discusses an example of plutonium casting operation using tantalum at LANL PF-4. The Whisper tool at Los Alamos relies on many inputs, including covariance data, leading the presentation to ask if an existing benchmark data be used in Whisper to adjust nuclear data and covariances to justify a higher USL. If not, Whisper can be used to help design an optimal new benchmark experiment. The presentation also seeks to determine what the possible impacts are on USL and operational limits for plutonium casting. In conclusion, nuclear data covariances are used for by Whisper for: GSSL adjustment of nuclear data and covariances, identification of most similar existing benchmark experiments to application, simulation of Upper Subcritical Limit of application, and input to optimization techniques for designing most appropriate new benchmark experiment(s) to meet requirements. This requires a complete set of nuclear data covariances, benchmarks and k-effective sensitivity profiles (for both benchmarks and applications). The presentation concludes by asking if end users should trust results that depend on current covariance data.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); USDOE Laboratory Directed Research and Development (LDRD) Program
• DOE Contract Number: 89233218CNA000001
• OSTI ID: 1894822
• Report Number(s): LA-UR-22-31233
• Resource Relation: Conference: Nuclear Data Uncertainty Quantification Working Meeting (NDUQWM), Held Virtually, Los Alamos, NM (United States), 11-13 Oct 2022
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
97 MATHEMATICS AND COMPUTING
Nuclear Criticality Safety Program (NCSP)
Analytical Methods
Upper Subcritical Limits (USL)
Whisper
Generalized Linear Least Squares (GLLS)
Gaussian Process (GP)
Latin Hypercube Sample (LHS)
ARCHIMEDES
Monte Carlo N-Particle Transport (MCNP)