Overview
EN ISO 12183:2024 - "Nuclear fuel technology - Controlled-potential coulometric measurement of plutonium" specifies a precise analytical method for determining plutonium in nuclear-grade plutonium nitrate solutions using controlled-potential coulometry. The fourth edition (ISO 12183:2024), adopted by CEN as EN ISO 12183:2024, replaces the 2019 version and sets performance and uncertainty targets for routine and accountability measurements in nuclear fuel technology.
- Scope highlights: applicable to aqueous plutonium solutions > 0.5 g·L−1 and test samples containing 4 mg to 15 mg plutonium.
- Performance: expanded uncertainty not exceeding ±0.2 % (confidence level 0.95, k = 2) for a single determination.
- No normative references are listed in the document.
Key topics and technical requirements
- Principle: controlled-potential coulometry with defined electrochemical steps (reduction and oxidation) to convert plutonium between oxidation states and measure the charge required, yielding mole quantity that is converted to mass using independent molar mass information.
- Sample preparation: fuming to anhydrous plutonium sulfate to remove chloride, fluoride, nitrate, nitrite, hydroxylamine and volatile organics; optional anion-exchange purification when interferences are present.
- Blank and background corrections: measurement of supporting-electrolyte blank and correction for charging, faradaic and residual currents.
- Electrolysis endpoints: controlled-potential adjustment to achieve > 99.8 % electrolysed plutonium fraction for both reduction and oxidation steps.
- Quality and uncertainty: clauses on repeatability, confidence intervals and analysis time; guidance on interferences, procedure variations, calibration methodologies and traceability to SI units (Clause 12).
- Annexes: informative guidance on anion-exchange purification and formal potential determination.
Applications and target users
EN ISO 12183:2024 supports high-accuracy plutonium assay needs in:
- Nuclear fuel fabrication and reprocessing laboratories
- Safeguards and regulatory accountability measurements
- Quality assurance and process-control laboratories in the nuclear fuel cycle
- Analytical chemists and metrology teams establishing traceability to SI units
Users applying the method to lower concentration solutions (