A NOVEL METHOD FOR SOLVING LITHIUM CARBONATE PELLET BY BINARY-ACID FOR TRITIUM PRODUCTION RATE MEASUREMENT BY LIQUID SCINTILLATION COUNTING TECHNIQUE

摘要

Lithium carbonate pellets are frequently used for estimation of tritium production rate in irradiated samples in fusion blanket neutronics experiment and the activity is measured by liquid scintillation counting technique. In this measurement, it is essential to solve the lithium carbonate pellet as much as possible and to mix the pellet solution into scintillation cocktail homogeneously at stable condition. For this purpose, a novel binary-acid method has been developed to solve lithium carbonate and to mix the pellet solution into scintillation cocktail. High solubility is attained by adopting two acids, HNO3 and CH3COOH, and a good compatibility of the pellet solution with scintillator is obtained by emulsion cocktail resulting in high counting efficiency. Defining a product of dissolved mass and counting efficiency as a Figure of Merit (FOM), the present method has higher FOM value than the conventional method and is extremely simple in a sample preparation procedure. In the present work, solubility, compatibility and counting efficiency were systematically examined for different mixing ratios of two acids, and the condition for a maximum FOM was determined. The FOM value of a factor of two higher than the conventional method was fully attained. [References: 13]