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Title: Enhanced nuclear waste assay
Author: Tree, K. A.
ISNI:       0000 0004 7964 2195
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2019
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The accountancy of all radioactive waste held in the UK continues to present challenges to the Nuclear Industry in terms of the regulatory, verification and international safeguards criteria. Characterisation of radioactive waste is an important part of the accountancy process. Current methods of characterisation include passive and active γ-ray spectroscopy techniques which involve expensive and resource intensive procedures. This thesis investigates an alternative to mechanical Compton suppression systems that are used to suppress the Compton Continuum in the context of non-destructive assay of radioactive waste using γ-ray spectroscopy. This is achieved by using a single broad energy germanium detector in conjunction with a Digital Compton Suppression Algorithm. The aim is to improve the Minimum Detectable Activity and to negate the use of hardware systems that use mechanical suppression, thereby reducing the overall cost and improving efficiency. The Digital Compton Suppression Algorithm has been developed with the aid of a theoretical charge signal database. The database was also used to perform electric field and weighting potential simulations. The algorithm was validated against an experimental data set using 241Am and 137Cs sealed sources. As a comparison, further tests were conducted at National Nuclear Laboratory Central Laboratory The results of the validation and comparison experiments show that the Digital Compton Suppression Algorithm has been successfully developed and that an improvement of (41.0±5)% in the Minimum Detectable Activity of the detector is achieved for the 60 keV peak of 241Am in the presence of a variety of isotopes.
Supervisor: Harkness-Brennan, Laura ; Boston, Helen Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral