ISO 8299:2019

Overview

ISO 8299:2019 specifies a validated laboratory method for determining the isotopic and elemental concentrations of uranium (U) and plutonium (Pu) in nitric acid solutions using thermal‑ionization mass spectrometry (TIMS). The standard addresses both isotopic composition analysis and isotope‑dilution mass spectrometry (IDMS) concentration measurements for irradiated fuels (Magnox and light‑water reactors), spent‑fuel reprocessing streams, and feed/products of MOX and uranium fuel fabrication. The procedure is adaptable to other fuel types with appropriate chemical separation and spike adjustments.

Key technical topics and requirements

• Analytical principle: TIMS isotope‑ratio measurements and IDMS for elemental assay (Clauses 4, 11–12).
• Sample preparation: Subsampling, spiking, valence adjustment and chemical separation for pellets, powders, concentrated solutions and dried nitrates (Clause 8).
• Separation media: Resin selection and preparation for U/Pu purification; ion‑exchange and extraction chromatography options (Clauses 5.3, 8.3).
• Spike and reference materials: Preparation and standardization of spike solutions for IDMS (Annex A; Clause 5.1).
• Filament and TIMS operation: Filament degassing, loading techniques (graphite, resin‑bead), filament assembly, and measurement modes (total evaporation, bias‑correction) (Clause 9, 11).
• Instrument calibration: Mass, detector gain, Faraday calibration, and mass‑discrimination correction procedures (Clause 10, 12.3).
• Data treatment: Calculation of ion currents, weighted means, atomic percent, isotopic mass percent, concentration, and decay correction (Clause 12).
• Quality assurance: Blanks, QC procedures, and comprehensive treatment of measurement uncertainty and interferences (Clauses 13–16).

Practical applications and users

ISO 8299:2019 is intended for:

• Nuclear fuel analytical laboratories performing U/Pu isotopic and concentration assays.
• Spent‑fuel reprocessing facilities and MOX/uranium fuel fabrication plants monitoring feed and product streams.
• Safeguards, regulatory and quality‑assurance teams requiring standardized, traceable TIMS protocols.
• Research institutions studying reactor‑irradiated materials and method development for nuclear forensics.

Typical uses include inventory verification, process monitoring in reprocessing plants, compositional control for fuel fabrication, and supporting nuclear safeguards and compliance reporting.

Related standards

• ISO 15366 (column extraction chromatography methods) - alternative separation techniques.
• ISO 11483 (alpha spectrometry) - complementary technique when isobaric interferences remain.
• ISO 10980 - validation of reference solution strengths.

Keywords: ISO 8299:2019, TIMS, thermal‑ionization mass spectrometry, IDMS, uranium plutonium isotopic analysis, nuclear fuel reprocessing, nitric acid solutions, MOX, measurement uncertainty.