Sensitivity-Uncertainty Based Nuclear Criticality Safety Validation

Technical Report · Tue Sep 20 00:00:00 EDT 2016

DOI:https://doi.org/10.2172/1325663· OSTI ID:1325663

Brown, Forrest B. ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States). Nuclear Engineering Dept.

These are slides from a seminar given to the University of Mexico Nuclear Engineering Department. Whisper is a statistical analysis package developed to support nuclear criticality safety validation. It uses the sensitivity profile data for an application as computed by MCNP6 along with covariance files for the nuclear data to determine a baseline upper-subcritical-limit for the application. Whisper and its associated benchmark files are developed and maintained as part of MCNP6, and will be distributed with all future releases of MCNP6. Although sensitivity-uncertainty methods for NCS validation have been under development for 20 years, continuous-energy Monte Carlo codes such as MCNP could not determine the required adjoint-weighted tallies for sensitivity profiles. The recent introduction of the iterated fission probability method into MCNP led to the rapid development of sensitivity analysis capabilities for MCNP6 and the development of Whisper. Sensitivity-uncertainty based methods represent the future for NCS validation – making full use of today’s computer power to codify past approaches based largely on expert judgment. Validation results are defensible, auditable, and repeatable as needed with different assumptions and process models. The new methods can supplement, support, and extend traditional validation approaches.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• Contributing Organization: Univ. of New Mexico, Albuquerque, NM (United States)
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 1325663
• Report Number(s): LA-UR--16-27172
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
42 ENGINEERING
97 MATHEMATICS AND COMPUTING
ADJOINT FLUX
CRITICALITY
DATA COVARIANCES
FISSION
M CODES
MCNP
MONTE CARLO METHOD
Monte Carlo
NEUTRON TRANSPORT
Nuclear Criticality Safety Program (NCSP)
PROBABILITY
SAFETY
SENSITIVITY ANALYSIS
VALIDATION
W CODES
WEIGHTING FUNCTIONS