Overview
EN ISO 21613:2017 (identical to ISO 21613:2015) specifies a standardized analytical method for the determination of chlorine and fluorine in mixed uranium–plutonium oxide-(U,Pu)O2-powders and sintered pellets. The procedure uses pyrohydrolysis (850–1 000 °C) with steam or moist oxygen to convert halogens to acidic forms that are trapped in an aqueous receiver and quantified. The method is applicable to samples containing 5 µg·g−1 to 50 µg·g−1 chlorine and 2 µg·g−1 to 50 µg·g−1 fluorine. For pure UO2 materials, see ISO 22875.
Key topics and requirements
- Principle: Pyrohydrolysis of (U,Pu)O2 at 850–1 000 °C; halogens volatilize as acids and are collected in an alkaline receiving solution.
- Analytical measurement: Quantification by fluoride and chloride selective electrodes or ion-exchange (ion) chromatography.
- Reagents and calibration: Use analytical-grade reagents (NaCl, NaF, NaOH, buffer solutions) and prepared chloride/fluoride reference solutions for electrode/IC calibration.
- Equipment: Tubular furnace for pyrohydrolysis, gas/steam supply (moist oxygen), receiving vessels (alkaline NaOH buffer), ion analysis systems or selective electrode setups, standard laboratory glassware and mortar for sample preparation.
- Quality control: The standard includes procedures for blanks, calculation and expression of results, validation limits, determination limits and estimation of measurement uncertainty.
- Scope limits: Explicit concentration ranges for reliable quantification; additional normative references (ISO 3696, ISO 22875, ISO 9892) are cited.
Applications and users
- Nuclear fuel manufacturing and quality control: Routine monitoring of halogen contamination in mixed oxide (MOX) feed powders and sintered fuel pellets to ensure material purity and performance.
- Analytical laboratories: Laboratories performing trace-level halogen analysis in radioactive or fissile materials where standardized, validated methods are required.
- Regulatory and R&D: Compliance testing, process development, failure investigation and material characterization for fuel technology and radiological protection research.
- Why it matters: Chlorine and fluorine impurities affect sintering behavior, corrosion and long-term fuel performance; this standard provides a reproducible, validated route for trace halogen determination in MOX fuels.
Related standards
- ISO 22875 - Determination of chlorine and fluorine in UO2 powder and sintered pellets
- ISO 3696 - Water for analytical laboratory use (reagent water quality)
- ISO 9892 - Fluoride ion selective electrode methods for uranium compounds
Keywords: EN ISO 21613:2017, ISO 21613:2015, (U,Pu)O2, chlorine and fluorine determination, pyrohydrolysis, ion chromatography, fluoride selective electrode, nuclear fuel quality, sintered pellets, MOX powder.
