Day, George (2018). The immobilisation of Caesium and Strontium from nuclear waste captured by IONSIV. University of Birmingham. Ph.D.
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Day2018PhD.pdf
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Abstract
A previous study revealed Cs\(_2\)TiNb\(_6\)O\(_1\)\(_8\) to be the major Cs-containing phase after hot isostatic pressing Cs-loaded IONSIV (a commercial exchanger) which demonstrated excellent wasteform properties. Both experimental and theoretical studies have been carried out in order to assess if Cs\(_2\)TiNb\(_6\)O\(_1\)\(_8\) is able to retain \(^1\)\(^3\)\(^7\)Ba\(^2\)\(^+\), the transmutation product of \(^1\)\(^3\)\(^7\)Cs\(^+\). A series of samples with different charge compensation mechanisms have been synthesised including Cs\(_2\)\(_-\)\(_x\)Ba\(_x\)Ti\(^(\)\(^4\)\(^+\)\(^)\)\(_1\)\(_+\)\(_x\)Nb\(^(\)\(^5\)\(^+\)\(^)\)\(_6\)\(_-\)\(_x\)O\(_1\)\(_8\), Cs\(_2\)\(_-\)\(_x\)Ba\(_x\)Ti\(^(\)\(^3\)\(^+\)\(^)\)\(_x\)Ti\(^(\)\(^4\)\(^+\)\(^)\)\(_1\)\(_-\)\(_x\)Nb\(_6\)O\(_1\)\(_8\) and Cs\(_2\)\(_-\)\(_x\)Ba\(_x\)TiNb\(^(\)\(^4\)\(^+\)\(^)\)\(_x\)Nb\(^(\)\(^5\)\(^+\)\(^)\)\(_6\)\(_-\)\(_x\)O\(_1\)\(_8\). Analysis suggested that Ba incorporation was not successful because of the identification of Ba impurities in the X-ray diffraction patterns. A series of atomistic simulations have also been performed to support the experimental work, using the General Utility Lattice Program code which suggested that Ba incorporation is not energetically favourable.
Sr-loaded IOSNIV has also been thermally converted via calcination (in air) and hot isostatic pressing. The removal and immobilisation of Sr is an important process on account of \(^9\)\(^0\)Sr being one of the more problematic radionuclides produced from the fission process. Both thermal conversion methods produced crystalline phase assembles which were analysed by X-ray diffraction, X-ray fluorescence and microscopy studies. The HIPed materials performed well in aqueous durability tests, suggesting these wasteforms will be suitable for final disposal in a geological disposal facility.
Type of Work: | Thesis (Doctorates > Ph.D.) | ||||||
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Award Type: | Doctorates > Ph.D. | ||||||
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College/Faculty: | Colleges (2008 onwards) > College of Engineering & Physical Sciences | ||||||
School or Department: | School of Chemistry | ||||||
Funders: | Other | ||||||
Other Funders: | The University of Birmingham | ||||||
Subjects: | T Technology > TA Engineering (General). Civil engineering (General) T Technology > TP Chemical technology |
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URI: | http://etheses.bham.ac.uk/id/eprint/8206 |
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