Determination of ⁶³Ni in Aluminum Alloy Samples From Nuclear Reactor Core by Liquid Scintillation Method

To establish a method of measuring the radioactivity of ⁶³Ni in aluminum alloy samples from nuclear reactor core, various relevant problems were studied. Samples were pretreated before liquid scintillation counting (LSC) by dissolution, anion exchange separation, hydroxide precipitation, and solvent extraction procedures. LSC-related parameters, such as sample solution acidity, sample solution-to-cocktail volume ratio, and added nickel carrier amount, were investigated. The detection efficiency of Tri-Carb 3110 liquid scintillation spectrometer with respect to ⁶³Ni for a series of ⁶³Ni standards of different activities are all better than 70%. The recommended experimental conditions are listed below: sample acidity 0.3 mol/L, sample-to-cocktail volume ratio 1∶2, Ni carrier amount 5 mg. The standard deviation of 0.077/s and the relative standard deviation of 15.3%(n=12) are found for blanks. The detection limit is 1.38 Bq/g. The present method is suitable to analyze samples for decommissioning of nuclear reactors.