Document Type

Annual Report

Publication Date

2002

First page number:

26

Last page number:

27

Abstract

The separation and partitioning of used commercial reactor fuel is a vital component of any reprocessing or transmutation strategy. To process the high actinide fuels required for a transmutation effort, the Chemical Technology Division (CMT) at Argonne National Laboratory (ANL) is developing a pyrochemical separations process. Currently, this work is being done via small experiments. While this is more than sufficient to develop the technologies required to process actinide-bearing fuels, it does not allow for the direct investigation of criticality concerns that would be present in larger systems. As the volume of waste to be treated increases, a higher probability exists that fissionable isotopes of plutonium, americium, and curium can accumulate, forming a critical mass. These criticality events can be avoided by ensuring the effective neutron multiplication factor, keff, remains below a safe level. Monte Carlo simulations to evaluate keff are the best way to examine the criticality safety of the proposed separation processes, and will allow engineers to develop proper safety measures for the reprocessing and fabrication of high actinide fuels.

A related problem for handling high actinide fuels is the heat generated by the decay of the higher actinides. In particular, the presence of curium in transuranic wastes poses a significant problem. To minimize the impact of curium on the fabrication of actinide-bearing fuels, the process engineers and chemists would like to remove the curium from the fuel. Curium, however, not only poses a criticality concern, but also includes isotopes that generate a great deal of decay heat. This heat generation creates safety problems with regards to handling and storing curium. The decay heat can cause samples to melt very quickly if excessive quantities of curium are present. SCALE, a Monte Carlo code, simulates the scattering and absorption of neutrons. This technique permits assessment of what quantities of curium will result in a critical mass. This information is then combined with thermal transfer models to examine the decay heat issue, and evaluate thermally and critically safe storage configurations for curium-rich waste streams.

Keywords

Actinide elements; Criticality (Nuclear engineering); Neutrons — Multiplicity; Reactor fuel reprocessing; Separation (Technology); Spent reactor fuels; Transmutation (Chemistry); Transuranium elements

Controlled Subject

Criticality (Nuclear engineering); Separation (Technology); Transmutation (Chemistry)

Disciplines

Chemistry | Nuclear | Nuclear Engineering | Oil, Gas, and Energy

File Format

pdf

File Size

115 KB

Language

English

Rights

COPYRIGHT UNDETERMINED. For more information about this rights statement, please visit http://rightsstatements.org/vocab/UND/1.0/

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