Doctoral Dissertations

Date of Award

12-2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Nuclear Engineering

Major Professor

Steven E. Skutnik

Committee Members

Howard L. Hall, G. Ivan Maldonado, Vasileios Maroulas

Abstract

NESTLE to ORIGAMI coupling is a versatile nuclear modeling tool that allows researchers to directly observe the impact of operator induced changes on LWR assembly isotope production. The paper presents an experimental method by which to test the ability of an operator to manipulate the core neutron spectrum in order to produce higher quality plutonium for weapons use. The paper presents two plutonium production scenarios and evaluates their feasibility based on potential for detection and production capacity. Reactor modeling of a VVER-1000 uses NESTLE core simulation software. NESTLE outputs burnup and relative power information for all nodes in the core. Burnup-weighted relative power serves as a conduit for assessing the impact of core environment changes to be captured during ORIGAMI depletion analysis. When used in a nonproliferation capacity, this tool gives safeguards professionals a method by which to verify the burnup declarations of an operator for spent nuclear fuel. This tool is useful for verifying irritation history in the case of an undeclared operator action such as the scenarios presented in this paper. NESTLE to ORIGAMI coupling is used to model the axial distribution of plutonium isotopes in the affected assembly so as to determine the suitability of the material for direct weapons use. Spent nuclear fuel isotope signatures commonly used in safeguards determine if the scenario would be detectable. Using NESTLE to ORIGAMI coupling it is determined that attempts to manipulate the neutron spectrum for producing illicit weapons useable plutonium in a LWR would be unfeasible due to the material being undesirable for weapons use, inefficient production rates, and the potential for detection.

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