Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016. / Boron concentration analysis is an important and critical analysis performed by the Analytical Chemistry Laboratory at Koeberg Nuclear Power Station (KNPS), because boron controls reactivity and the concentration determination is a Technical Specification Parameter (safety parameter). Hence accurate, precise results for boron concentration produced by laboratories and on-line analysers are important because of their operational implications associated with reactivity control and also for nuclear safety. The project focused on comparing the quality of chemical analysis results of boron produced by analysis techniques/ methods used at Koeberg Nuclear Power Station namely; Potentiometric Titration, Atomic Absorption Spectrophotometry (Flame) and UV-VIS Azomethine-H method. The methods were described, optimised, evaluated and compared in terms of uncertainty of measurement, accuracy, precision, analysis range, limitations, appropriateness and applicability for boron analysis in 2500 mg B/kg concentration range. For Potentiometric Titration method, the measurement uncertainty = 2500 ±16 mg B/kg, accuracy= 0.2%, precision= 0.08% the range of analysis= 5-800 mg B/kg. For Atomic Absorption Spectrophotometry (Flame) the measurement uncertainty= 2500 ±51 mg B/kg, accuracy= 0.12%, precision= 0.44% the range of analysis= 0 -500 mg B/kg. For UV-VIS Azomethine-H the measurement uncertainty= 2500 ±72 mg B/kg, accuracy= 0.08%, precision= 0.44% the range of analysis= 0 -10 mg B/kg. The INPOs 95% accuracy and precision criteria for boron is ± 1%. So these techniques could be used for boron analysis in PWR. Based on the evaluation and assessments mentioned above; the Potentiometric Titration was found to be the most preferred method for boron analysis for Pressurised Water Reactors followed by Atomic Absorption Spectrophotometry (Flame) that can be of good use in determining boron especially in waste samples and samples with complex matrices. The UV-VIS Azomethine-H methods can only be used when it is really necessary to determine very low levels of boron between 0- 10mg B/kg of which it was never required before. Since it is specifically the B-10 isotope that is responsible for the ability to control reactivity, the implementation of isotopic boron analysis (by Inductively Coupled Plasma – Mass Spectrometry) at KNPS is explained and the advantage of the programme is illustrated. Although the current state of instrumental capabilities is adequate for 10B isotope determination, further work of optimising the methodology for even better results is recommended.

This is Part B of the Thesis. Here is the Link to Part A: http://hdl.handle.net/11375/17844 / <p> This report deals with the effects of various parameters on the resistance and the temperature coefficient of resistance (or the T.C.) of tin dioxide films doped with antimony and boron. The films were produced on cylindrical ceramic substrates by the hydrolysis of SnCl4 and SbCls in the presence of HCl and H3BO3. The T.C. was measured over the range of 25 to 150°C and averaged.</p> <p> Under normal conditions, the films were produced at 950°C with an antimony concentration of 0.457 molar % and a boron concentration of 2.73 molar %. Varying this firing temperature (from 800-1100°C) was found to have no effect on the resistance but increased the T.C. by 2 to 3 ppm/°C per degree change. Varying the antimony content from 0 to about 1 molar % was found to have little effect on resistance. The effect on T.C. was to increase it at lower Sb levels and then to decrease the T.C. as the level increased.</p> <p> Varying the boron content (0 to 4.46 molar %) was also found to have little effect on resistance. A decrease in T.C. with boron content was noted when only the boron was varied, but an increase in T.C. was found when HCl and H2O volumes were varied with the boron. The introduction of additional air into the system was found to have no effect.</p> <p> Film thicknesses were varied by controlling the chemical flowrates. Thinner films were found to have dramatically higher resistances and reduced T.C. values. It was observed that below a certain flowrate resistive failure occurred in the films. It was found in this study that within the statistical distribution of film values, those samples with above average resistance had below average T.C. values and vice-versa. Annealing in vacuum at 500°C was found to produce samples of reduced resistance and increased T.C. while the opposite was found with air annealed samples. Quickly cooled samples were found to be more stable.</p> / Thesis / Master of Engineering (MEngr)