Overview
ISO 21613:2015 specifies an analytical method for the determination of chlorine and fluorine in mixed uranium–plutonium oxide - (U,Pu)O2 powders and sintered pellets. 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. The standard was developed by ISO/TC 85 (Nuclear energy) and provides laboratory procedures suitable for nuclear fuel quality control and research.
Key Topics
- Principle: Release of halogens by pyrohydrolysis (850 °C–1 000 °C) in a tubular furnace with steam or moist oxygen; halogenated acids are trapped in an alkaline aqueous receiver.
- Measurement techniques:
- Ion-selective electrodes (chloride and fluoride electrodes with a suitable reference electrode) - calibrated using prepared reference solutions.
- Ion-exchange (ion) chromatography as an alternative analytical method.
- Analytical range and limits: Designed for low µg·g−1 levels of Cl and F as stated in the scope.
- Reagents and calibration: Use of high-purity reagents and demineralised water (ISO 3696); prepared standard reference solutions (NaCl, NaF) and sodium hydroxide buffer solutions for absorption and calibration.
- Equipment: Tubular furnace with temperature control, steam generator, inert/compatible reaction tubes and condensers (Inconel®, platinum, quartz), combustion boats, volumetric glassware, millivolt meter, ion-selective electrodes, or chromatography system.
- Quality assurance: Blank tests, calibration curves, validation limits, and uncertainty assessment are included in the procedure to ensure reliable results.
Applications
- Nuclear fuel manufacturing: Routine quality control of MOX (mixed oxide) powders and pellets to monitor halogen contamination that can affect sintering, fuel behavior and cladding corrosion.
- Fuel cycle laboratories: Analytical verification of feedstock and product specifications during fabrication and reprocessing.
- Regulatory and safety testing: Compliance with specified impurity limits in nuclear materials.
- Research and development: Materials characterization in studies of sintering behavior, impurity effects, and process optimization.
Who Should Use This Standard
- Analytical chemists and laboratory technicians in nuclear fuel fabrication facilities
- Quality assurance and R&D teams in nuclear industry
- Accreditation bodies and regulatory laboratories performing trace halogen analysis in nuclear materials
Related Standards
- ISO 22875 - Determination of chlorine and fluorine in UO2 powder and sintered pellets (for pure uranium dioxide)
- ISO 9892 - Fluoride determination methods (ion-selective electrode)
- ISO 3696 - Water for analytical laboratory use (specification and test methods)
Keywords: ISO 21613:2015, (U,Pu)O2 powders, sintered pellets, chlorine determination, fluorine determination, pyrohydrolysis, ion-selective electrode, ion chromatography, nuclear fuel quality control.