|
|
An assessment of interferences influence on tritium volume activities measurement in liquid discharges of Temelin NPP
ŘEHÁČEK, Martin
The aim of this bachelor thesis is to evaluate the importance of selected disturbance effects on the accuracy of tritium determination in wastewater by means of liquid scintillation spectrometry. The thesis studies three disturbance effects: the pH of the sample, the UV radiation illumination of the sample and increased background in sample measurement caused by samples containing beta and gamma radiation emitting radionuclides placed inside the analyzer. The TriCarb 2910TR measuring analyzer and Ultima Gold XR scintillation cocktail were used for the study. Four samples with the following tritium volume activity were prepared for the study: < 3,7 Bq/l, 199,1 +- 4.1 Bq/l, 20 298,2 +- 73,5 Bq/l and 2 659 078,8 +- 6555,2 Bq/l. Each sample was influenced by disturbance effects of increasing intensity. For the experiment with the pH effect, a set of 12 samples with a pH ranging from 1 to 12 was prepared. For the illumination of samples, a room illuminated with fluorescent lamps, which are also a source of UV radiation besides visible radiation, was used. To examine the effect of increased background, three samples containing isotopes of caesium 134Cs and 137Cs emitting beta and gamma rays were prepared. Each sample was gradually affected by these disturbance factors and measured ten times. The measured data were statistically processed and evaluated. The conducted experiment and the statistical processing of the results, taking into account the accuracy of the instrument, revealed that the disturbance effects of the increased background of beta and gamma radiation and UV light exposure only have a significant effect on samples with very low tritium activity. In samples with high tritium activity, this effect is insignificant. The examination of the effect of the pH confirmed that the scintillation cocktail used showed satisfactory stability of the efficiency of the conversion of beta radiation to photons in the pH range of 2-12.
|
guest ::
