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Measurement and analysis of the resolved resonance cross sections of the natural hafnium isotopes

Ware, Timothy Christopher (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

Hafnium is a ductile metallic element with a large neutron absorption cross section. It can be used in reactor control rods to regulate the fission process. The NEA High Priority Request List for nuclear data presents a need for improved characterisation of the hafnium cross section in the resolved resonance region. This thesis presents new resonance cross section parameters for the six natural hafnium isotopes. Cross section measurements, supported by the NUDAME and EUFRAT projects, were performed at the IRMM Geel GELINA time-of-flight facility. Capture experiments were conducted on the 12 m, 28 m and 58 m flight paths using C\(_6\)D\(_6\) detectors and transmission experiments were performed at flight paths of 26 m and 49 m using a \(^6\)Li glass detector. The samples used were metallic natural hafnium discs of various thicknesses and hafnium oxide powders, with differing isotopic enrichments. Data analysis was performed using the least square fitting REFIT code, which was updated during this work. The use of isotopically-enriched samples enabled previously unrecorded resonances to be allocated to the correct isotope. The resulting evaluated data files extend the upper energy limits of the resolved resonance regions for the \(^{174}\)Hf, \(^{176}\)Hf, \(^{177}\)Hf, \(^{178}\)Hf, \(^{179}\)Hf and \(^{180}\)Hf isotopes, relative to the current European recommended evaluation (JEFF3.1), to 250 eV, 3 keV, 1 keV, 3 keV, 1 keV and 3 keV respectively. The natural hafnium resonance integral calculated from the new resonance parameters is 1.2% lower than the integral corresponding to the JEFF3.1 evaluated hafnium data. Comparison of calculated to experimental k-effective values for appropriate zero-power reactor assemblies show improvement over the JEFF3.1 data.

Type of Work:Ph.D. thesis.
Supervisor(s):Weaver, David
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Physics and Astronomy
Subjects:QC Physics
Institution:University of Birmingham
ID Code:807
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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