IEC 60794-1-207:2025

Overview

IEC 60794-1-207:2025 - "Optical fibre cables - Basic optical cable test procedures - Environmental test methods - Nuclear radiation, Method F7" defines uniform test procedures for assessing radiation-induced performance degradation of optical fibre cables. The first edition (2025) replaces Method F7 from IEC 60794‑1‑22:2017 and provides expanded, detailed requirements for samples, apparatus, procedures, pass/fail criteria and reporting. It covers both mixed optical/electrical cables and optical-fibre units (including microduct units) used in telecommunications and similar systems.

Key topics and requirements

• Scope of Method F7: two sub-methods
  • F7A - evaluates performance under environmental background radiation (low dose/dose rate).
  • F7B - evaluates performance in adverse nuclear environments (higher dose/dose rate).
• Sample preparation
  • Test sample length chosen to produce an induced attenuation of 3–10 dB at end of irradiation.
  • Spool/drum requirements: radius ≥ the larger of 10 cm or the cable minimum bending radius; reels should not act as radiation shields.
  • Minimise influence of fibre leads to < 10% of total induced attenuation.
• Apparatus and measurement
  • Ionizing radiation source (typically 60Co or equivalent); source on/off time < 10% of total exposure.
  • Radiation dosimetry: thermoluminescent detectors (LiF or CaF) or ion chamber to measure dose received by specimen.
  • Temperature-controlled container able to maintain specified temperature within ±2 °C.
  • Attenuation measurement equipment in accordance with IEC 60793‑1‑54 and IEC 60793‑1‑46 (monitoring changes in attenuation).
• Test procedure essentials
  • Calibration for dose uniformity and level at multiple positions (four positions recommended) where the reel will be placed.
  • Pre-conditioning, baseline attenuation measurement, controlled radiation exposure, and post-exposure measurements.
• Safety and competence
  • Strict radiation safety, trained personnel and appropriate protective facilities required.
• Reporting
  • Detailed specification and reporting requirements are defined for reproducibility and procurement.

Applications

• Qualification and selection of radiation-resistant optical fibres, cable materials and constructions for:
  • Nuclear power plants, nuclear laboratories and reactor-adjacent installations
  • Military and defense communications operating in radiation-prone environments
  • Space, avionics and other industries where ionizing radiation exposure is a concern
• Informs procurement specifications, design choices (e.g., metal sheaths, composite screens) and acceptance testing for critical telecom infrastructure.

Who should use this standard

• Cable manufacturers and R&D teams
• Independent test laboratories and certification bodies
• Telecom operators and infrastructure procurement engineers
• Defence, nuclear facility and safety engineering teams
• Standards committees and product qualification groups

Related standards

• IEC 60794-1-2 (general guidance)
• IEC 60793-1-46, IEC 60793-1-54 (attenuation measurement and gamma irradiation)
• IEC 60794-1-201 (temperature cycling, F1)
• IEC 60794-1-209 (ageing, F9)
• IEC 60544-1 (radiation dosimetry)

Keywords: IEC 60794-1-207, Method F7, nuclear radiation testing, optical fibre cables, radiation-induced attenuation, Co-60, radiation dosimeter, radiation-resistant fibre.