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Advanced nodal methods for MOX fuel analysis

IP.com Disclosure Number: IPCOM000128094D
Original Publication Date: 1997-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 7 page(s) / 23K

Publishing Venue

Software Patent Institute

Related People

Palmtag, Scott P: AUTHOR [+3]

Related Documents

http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1997-310: URL

Abstract

One method being considered for the disposal of surplus weapons grade plutonium is to burn the plutonium as mixed oxide fuel (MOX) in commercial light water reactors (LWR's). The introduction of MOX fuel into LWR's poses several challenges for the reactor analyst.

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 This record is the front matter from a document that appears on a server at MIT and is used through permission from MIT. See http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1997-310 for copyright details and for the full document in image form.

Advanced Nodal Methods for MOX Fuel Analysis

by

Scott P Palmtag


M. S., Nuclear Engineering, Massachusetts Institute of Technology (1995) B. S., Nuclear Engineering, University of Missouri-Rolla (1993)

Submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY at the Massachusetts Institute of Technology August 1997
(c) Scott P. Palmtag,1997. All rights reserved.

THE AUTHOR HEREBY GRANTS TO M.I.T. PERMISSION TO REPRODUCE AND TO DISTRIBUTE COPIES OF THIS THESIS DOCUMENT IN WHOLE OR IN PART. SIGNATURE OF author: [[signature omitted]]

Department of Nuclear Engineering

August 8, 1997

CERTIFIED BY: [[SIGNATURE OMITTED]]

Allan F. Henry Professor of Nuclear Engineering Thesis Supervisor Kord S. Smith
Vice-President, Studsvik of America Thesis Supervisor Kent F. Hansen
Professor of Nuclear Engineering Thesis Reader ACCEPTED BY: [[SIGNATURE OMITTED]]

JeffreyT Freidberg Chairman, Departmental Committee on Graduate Students

ARCHIVES MASSACHUSETTS INSTITUTE OF TECHNOLOGY LIBRARIES JUL 20 1999

Massachusetts Institute of Technology Page 1 Dec 31, 1997

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Advanced nodal methods for MOX fuel analysis

Advanced Nodal Methods for MOX Fuel Analysis

by Scott P. Palmtag

Submitted to the Department of Nuclear Engineering on August 8, 1997, in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY

Abstract

One method being considered for the disposal of surplus weapons grade plutonium is to burn the plutonium as mixed oxide fuel (MOX) in commercial light water reactors (LWR's). The introduction of MOX fuel into LWR's poses several challenges for the reactor analyst.

The spectrum difference between MOX and UO,) assemblies creates a large thermal flux gradient at the interface between these assemblies. Current nodal methods, which use a transverse leakage approximation, have difficulty modeling this gradient. In this thesis, an advanced nodal method is introduced which uses a two-dimensional, non-separable expansion of polynomial and hyperbolic functions to represent the two-group flux, rather than the transverse leakage approximation.

The steep thermal flux gradient also introduces errors in the spatial cross section homogenization. The spatial flux shape used to generate two-group cross sections does not account for the steep gradient, and therefore, the cross sections may be inaccurate. In this thesis, the cross sections are dynamically homogenized using the actual flux shape found in the reactor configuration. This is done by using a consistent method of spatial homogenization derived directly from the assumption of homogeneous and heterogeneous flux separability. From this assumption, discontinuity factors, homogenized cross sectio...