ISO 9978:2020

Overview

ISO 9978:2020 - "Radiation protection - Sealed sources - Leakage test methods" defines standardized methods to detect leakage from sealed radioactive sources. The standard provides a comprehensive set of radioactive and non‑radioactive leak test procedures for use during design testing, production quality control and periodic in‑service inspections. Annex A offers guidance for selecting the most suitable test(s) by source type and application. ISO 9978 emphasizes that following the standard complements but does not replace applicable IAEA or national regulatory requirements.

Key topics and requirements

• Scope of tests: Methods cover leakage testing after ISO 2919 design classification, production QC, and routine inspections during service life.
• Test families:
  • Radioactive means: immersion tests (hot, boiling, room temperature, liquid scintillator), gaseous‑emanation tests (e.g., radium‑226, krypton‑85), and wipe tests (wet and dry).
  • Volumetric (non‑radioactive) means: helium mass spectrometer testing (including pressurisation variants), bubble leakage tests (vacuum, hot‑liquid, gas pressurisation, liquid nitrogen) and water pressurisation tests.
• Acceptance and sensitivity: The standard specifies acceptance criteria and threshold detection values for different methods; measurement uncertainty must be considered for non‑binary results.
• Test programme design: Choice of method depends on chemical form of the active material, capsule construction, number of encapsulations, internal void volume, source temperature, environment, and required sensitivity.
• Competence: Tests must be designed, validated and performed by qualified personnel with demonstrable training. For methods involving radioactivity, appropriate radiation protection and measurement training is required (informative reference to ISO 9712 for NDT personnel qualification).
• Limitations and context: The document notes circumstances may require special tests not described and that some low‑activity sources may be exempted by national regulations.

Practical applications - who uses ISO 9978

• Manufacturers of sealed sources for design validation and production quality control.
• Test and calibration laboratories performing leak testing by radioactive assay or tracer gas methods.
• Radiation protection officers and safety managers conducting periodic inspections and maintenance.
• Regulatory authorities and transport/packaging engineers verifying leak tightness for storage and transport compliance.
• Procurement/specification authors who need to define acceptable leak test methods and acceptance criteria in contracts or QA documentation.

Related standards and references

• ISO 2919 (sealed source design classification)
• ISO 20485 (tracer gas/helium leak testing)
• ISO 9712 (NDT personnel qualification)
• ISO 19361, ISO 19581, ISO 7503‑2 (assay and wipe testing guidance)
• Relevant IAEA and national regulations (regulatory compliance remains mandatory)

Keywords: ISO 9978, sealed sources, leakage test methods, radiation protection, leak testing, helium leak test, immersion test, wipe test, gaseous emanation, quality control, sealed radioactive sources.