Modeling and simulation of the dissolution of a physical system with application to head-end operations in aqueous reprocessing

An electrochemically-based model of crystal dissolution is eveloped and implemented in a C++- and MPI-based parallel program in which (electro-)chemical reactions are formulated as Monte Carlo rules. The electrochemical model used assumes bonding in the solid to be a function of first nearest neighbors only, although more general reactions are also supported. The first-nearest-neighbor model is used for numerical experimentation with the dissolution of cubic crystals (for both face-centered cubic, coordination number Z = 12, and simple cubic, Z = 6 systems). Results are compared to existing theoretical predictions for dissolution. Qualitative agreement with results presented in literature is found for simple- and face-centered-cubic crystals. Alpha-phase uranium metal behavior is also considered, and indicates some inadequacies in the first-nearest-neighbor model used. Dissolution in 15.6N HNO3 is numerically simulated and compared to results in literature. The integral dissolution rate of the simulation corresponds with experimental results due to the degree of control of parameters in the model. However, details of the local features do not always coincide with observed experimental behavior; specifically, pitting behavior on the various crystal faces coincide on the euhedral faces and not on the rough faces. Further development of the microkinetics of uranium surface reactions will improve the quality of the model.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Nuclear Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Davis, Neal E.

Contributors dc:contributor

• Uddin, Rizwan

• nearest-neighbor bonding
• chemical simulation
• electrochemical simulation
• Monte Carlo simulation
• used nuclear fuel reprocessing
• crystal dissolution

Statement dc:rights

• Copyright 2011 Neal E. Davis

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/24137

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/24137