Overview
ISO 10981:2004 - Nuclear fuel technology - Determination of uranium in reprocessing-plant dissolver solution - Liquid chromatography method - specifies a liquid‑chromatography procedure to measure uranium concentration in nitric acid solutions of irradiated fuel. The method covers concentrations from 0.1 g·L⁻¹ to 400 g·L⁻¹, is applicable to dissolver solutions from light‑water, gas‑cooled and fast‑breeder reactors, and is intended for process control, not for nuclear material accountancy.
Key topics and technical requirements
- Analytical principle: ion‑pair partition chromatography on a grafted‑silica reversed‑phase column (C1/C2 type) with UV detection and peak‑area integration referenced to standards.
- Sample preparation: dilute sample in aqueous ascorbic acid (5×10⁻³ mol·L⁻¹) to lower free nitric acid so injected solution pH is between 1 and 3; ascorbic acid also reduces nitrite and Pu(IV)/Pu(VI) to non‑interfering forms.
- Chromatographic conditions:
- Injection volume: 1 µL (internal loop)
- Typical retention time for uranium: ≈ 5 minutes, complete elution by ~8 min
- Column: 10 cm × 4.6 mm (with 3 cm precolumn recommended)
- Mobile phase: acetonitrile–water (25–75% v/v) with cetyltrimethylammonium bromide, NaHSO4 and (NH4)2SO4; 0.1% trifluoroacetic acid added, degassed.
- Detection: UV spectrophotometry - fixed wavelength around 254 nm commonly used; variable‑wavelength (210–230 nm) or diode‑array detectors recommended for peak confirmation.
- Performance: repeatability CV ≈ 0.4–0.6% at 200 g·L⁻¹ (improves to ~0.2% with automatic diluter). Systematic bias vs isotopic dilution MS is −0.1% to +0.4% (user evaluation recommended).
- Interferences: nitrite and Pu(IV/VI) are prevented by ascorbic acid reduction; other fuel solution constituents listed in the standard do not interfere at typical concentrations.
Applications and users
- Intended for process control in nuclear reprocessing plants to monitor uranium concentration in dissolver streams.
- Primary users:
- Analytical laboratories in reprocessing facilities
- Nuclear fuel technologists and process chemists
- Quality control teams monitoring dissolution and downstream operations
- Not suitable for safeguards/accountancy or legal material balance reporting.
Related standards
- ISO 8299 (referenced): thermal‑ionization mass spectrometry method for isotopic and elemental uranium/plutonium concentrations - used for accountancy and high‑accuracy comparisons.
Keywords: ISO 10981:2004, uranium determination, liquid chromatography, reprocessing‑plant dissolver solution, nitric acid, ascorbic acid reduction, ion‑pair chromatography, UV detection, process control.