Nuclear Engineering ETDs

Publication Date

Spring 4-14-2021

Abstract

The Annular Core Research Reactor (ACRR) Monte Carlo N-Particle (MCNP) model is used for a variety of computational calculations ranging from reactor kinetics metrics to safety analyses. To understand the dominant source of uncertainty within the model, perturbations in temperature were applied to individual ACRR MCNP fuel rods. Assigning random temperatures, selected uniformly, from the operational temperature ranges of the fuel enables a study of uncertainty effects based on temperature variations. Stochastic mixing was used to blend the cross-sections of the desired temperatures using the MCNP continuous and Thermal Neutron Scattering Treatment (S(α,β)) libraries in ENDF/B-VII.1. The uncertainty quantification process produced a 640 row by 640 column correlation and covariance matrix of the neutron energy spectra. Variance was produced around the 1 MeV region and the 0.2 eV region. The correlation matrix is affected in the thermal and fast energy regions, but the slowing down energy region stayed unchanged because it is dominated by the moderator cross-sections. Some of the uncertainties can be attributed to the nuclear data and the doppler broadening associated with the temperature variation.

Keywords

MCNP, Perturbation, Monte Carlo, ACRR, Covariance Matrix, Correlation Matrix, Uncertainty Quantification, Stochastic Mixing

Sponsors

Sandia National Laboratories Radiation Effects Science (RES) Campaign Mission

Document Type

Thesis

Language

English

Degree Name

Nuclear Engineering

Level of Degree

Masters

Department Name

Nuclear Engineering

First Committee Member (Chair)

Christopher Perfetti

Second Committee Member

Danielle Redhouse

Third Committee Member

Forrest Brown

Fourth Committee Member

Cassiano Endres de Oliveira

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