The study of substitutability of liquid scintillation cocktail for YAP:Ce powder

et al. 2019

The liquid scintillation counting (LSC) is an established method for direct quantitative measurement of tritiated water, but the generated radiotoxic waste, its storage, handling and proper disposal is the major concern arising from using scintillation cocktail. In our work, CaF 2 (Eu) was chosen as the scintillation material to substitute scintillation cocktail in low-level tritiated water measurement. In order to find out the ideal vial type, grain size of powders and CaF 2 (Eu) powders quantity, three groups of 6 and 20 ml scintillation vials filled with different CaF 2 (Eu) powders were prepared. Using polyethylene vial, which is much smaller than the glass vial, significantly increased the detection efficiency. The highest detection efficiency was achieved by using polyethylene vial and 4 g S sample (average grain sizes: 8.355 µm). In addition, the polyethylene vials with 4 g S sample inside were most sensitive and had the best linear relation between tritium concentration and count rate. Under this condition, the detection limit can be as low as about 13 Bq/mL. The CaF 2 (Eu) powder can be re-used after a simple treatment. What's more, it is nontoxic as well as easy to store and disposal. These make it advantageous compared with traditional scintillation cocktail. With these results, the replacement of the scintillation cocktail with CaF 2 (Eu) powder in low-level tritiated water measurements is promising.

Section: Introductionmentioning

confidence: 99%

The substitutability of liquid scintillation cocktail for CaF₂(Eu) powder in low-level tritiated water measurement

et al. 2019

“…The liquid scintillation counting (LSC) is an established method for direct quantitative measurement of tritiated water, but the generated radiotoxic waste as well as its storage, handling and proper disposal are the major concern arising from using scintillation cocktail. Recently, the substitutability of liquid scintillation cocktails with YAP:Ce, YAG:Ce, ZnO:Ga powders has been studied [7,8], but these solid scintillation materials were not used for tritiated water measurement.…”

Section: Introductionmentioning

confidence: 99%

A new low-level tritiated water measurement system using CaF₂(Eu) powders

Wang

et al. 2019

With the development of ITER and CFETR, the measurement of tritium in low-level tritiated water is indispensable from the viewpoint of assessment and safety of tritium. To reduce radioactive waste produced by liquid scintillation counting, we have built a new low-level tritiated water measurement system using CaF 2 (Eu) powders. When an 8 mm thickness sample chamber and M sample (average grain sizes: 59.1 µm) were used, our measurement system responded accurately to tritium concentrations down to approximately 2.6 Bq/mL for 10 min measurements, and the calculated detection limit was about 4.6 Bq/mL. When a 3 mm thickness sample chamber and S sample (average grain sizes: 8.4 µm) were used, our measurement system responded accurately to tritium concentrations down to approximately 1.2 Bq/mL for 10 min measurements, and the calculated detection limit was about 0.64 Bq/mL.

“…Recently, substitutability of liquid scintillation cocktails with YAP:Ce, YAG:Ce, ZnO:Ga powders has been studied [6,7]. Since CaF 2 (Eu) hardly dissolves in water and has high light yield, it is an ideal material for low-level tritiated water measurement.…”

mentioning

confidence: 99%

The effect of particle size of CaF₂(Eu) powder and chamber thickness on solid scintillation counting for low-level tritiated water measurement

Wang

2018

With the development of the International Thermonuclear Experimental Reactor (ITER) and the China Fusion Engineering Test Reactor (CFETR), the measurement of tritium in low-level tritiated water is indispensable from the viewpoint of assessment and safety of tritium. In our work, CaF 2 (Eu) was chosen as the scintillation material in the research to design a tritium monitor for tritiated water. The effect of particle size of CaF 2 (Eu) powder and chamber thickness on detection efficiency and count rate were assessed by Geant4 simulation. Our results show that reducing the CaF 2 (Eu) particle size can effectively improve the probability of energy deposition in the scintillator. Under the same conditions, the use of CaF 2 (Eu) particles with a radius of 0.5 µm increases the energy deposition probability by a factor of more than 20 compared to particles with a radius of 50 µm. However, the coincidence detection efficiency rapidly decreases as the chamber thickness of the solid scintillation counting (SSC) system increases when the particle size is small. With a fine CaF 2 (Eu) powder (particle radius of 1 µm), the coincidence detection efficiency is greater than 50% when the chamber thickness is 1 mm. Only approximately 35% of tritium decay is coincidentally detected when the chamber thickness is 5 mm. In addition, filling the chamber with CaF 2 (Eu) particles of different sizes leads to different maximum count rates. With the finest CaF 2 (Eu) powder, the SSC system has the highest count rate when the chamber thickness is 5 mm. With such results, the replacement of the scintillation cocktail with CaF 2 (Eu) powder in low-level tritiated water measurements is very promising. The simulation result will help in the design of a SSC system applied to low-level tritiated water measurement, and such a system will be tested in our future work. K: Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc); Very low-energy charged particle detectors 1Corresponding author.