ISO 24390:2023

Overview

ISO 24390:2023 - "Nuclear energy - Nuclear fuel technology - Methodologies for radioactivity characterization of very low-level waste (VLLW) generated by nuclear facilities" provides standardized methodologies to characterize radioactivity in very low-level waste (VLLW) produced during operation or decommissioning of nuclear facilities. The standard focuses on radioactive solid waste and is intended to differentiate VLLW from higher-level low-level waste (LLW) and from waste below clearance levels. It supports demonstrating that waste meets waste acceptance criteria (WAC) for near-surface landfill-type disposal or alternative routes. Clearance/exemption monitoring and liquid or gaseous waste characterization are explicitly excluded.

Key topics and technical requirements

• Waste Acceptance Criteria (WAC): Defines radiological, physical, chemical and package-related criteria that VLLW must meet for acceptance by disposal or processing facilities. WAC should be measurable, verifiable and justified (e.g., via DQO).
• Radioactivity characterization process: A multi-step approach detailed in the standard, including:
  • Step 1 - Investigation of waste characteristics
  • Step 2 - Surface scanning (NDA in situ)
  • Step 3 - Gamma activity measurement
  • Step 4 - Destructive analysis (laboratory radiochemical/chemical methods)
• Measurement methodologies: Use of non-destructive analysis (NDA) for in situ gamma-emitting nuclides and destructive analysis (e.g., radiochemistry, ICP‑MS) for difficult-to-measure (DTM) radionuclides.
• Correlation methods: Guidance on scaling factor and nuclide vector approaches to infer DTM radionuclide activity from key (gamma) radionuclides.
• Sampling strategies: Procedures for homogeneous vs heterogeneous waste, and quantification of sampling uncertainty.
• Decision thresholds and data quality: Definition of decision thresholds, data quality objectives (DQO) and quality assurance provisions for labs, instruments, personnel and documentation.
• Quality Assurance: Requirements for traceability, QA/QC, and documented procedures.

Practical applications and users

ISO 24390:2023 is primarily used by:

• Nuclear facility operators and decommissioning teams for waste classification and routing.
• Radioactive waste managers and disposal site operators to define and verify WAC compliance.
• Analytical laboratories performing destructive assays for DTM radionuclides.
• Regulators and safety assessors evaluating waste acceptance, environmental protection and public safety.
• Consultants designing characterization programs and sampling plans.

Benefits include improved consistency in VLLW classification, defensible measurement strategies, optimized waste routing (including potential reuse/recycling), and enhanced protection of people and the environment.

Related standards

• ISO 12749-3 (vocabulary for nuclear fuel cycle)
• ISO 21238 / ISO 18557 (related methods for radionuclide correlation and DQO concepts)

Keywords: ISO 24390:2023, VLLW, very low-level waste, radioactivity characterization, waste acceptance criteria, non-destructive analysis, destructive analysis, scaling factor, nuclide vector, nuclear decommissioning.