EN IEC 62397:2026

Overview

EN IEC 62397:2026 establishes comprehensive requirements for resistance temperature detectors (RTDs) deployed in the instrumentation and control (I&C) systems important to safety in nuclear power plants (NPPs). Produced by CLC as an adoption of IEC 62397:2022, this European Standard ensures RTDs fulfill the demanding performance, reliability, and quality criteria essential for nuclear safety applications. It covers all aspects from design and material selection to manufacturing, procurement, inspection, testing, and calibration.

The standard addresses RTDs used in both safety and non-safety instrumentation systems in NPPs, including direct-immersed and thermowell-mounted types. While the guidance does not extend to thermowell design or associated equipment such as extension cables or transmitters, it details critical requirements to guarantee that RTDs contribute effectively to plant safety and operational integrity.

Key Topics

EN IEC 62397:2026 focuses on the following principal areas for safety-important RTDs:

• Design and Materials

  • General requirements for RTD construction tailored to nuclear power applications.
  • Material selection to withstand nuclear environments, including radiation and high temperature.
  • Emphasis on reliability, longevity, and resilience against environmental stresses.

• Manufacturing and Quality

  • Stringent manufacturing processes for consistency and reduction of defects.
  • Requirements for quality assurance (QA) throughout procurement and production.
  • Guidance for inspection and compliance with relevant quality management standards.

• Testing and Calibration

  • Procedures for RTD testing, including environmental (vibration, damp heat), functional, and response-time tests.
  • Calibration protocols ensuring accurate and dependable temperature measurement.
  • Qualification and periodic in situ validation methods such as cross-calibration.

• Performance Criteria

  • Requirements on accuracy, response time, repeatability, and immunity to self-heating errors.
  • Electrical, mechanical, and environmental performance assessments.
  • Specific provisions for identification, documentation, and maintenance strategy.

• Categories of RTDs

  • Direct-immersed RTDs: Installed directly in the measured medium.
  • Thermowell-mounted RTDs: Protected by a thermowell for easy replacement and enhanced durability.

Applications

RTDs qualified to EN IEC 62397:2026 are crucial for:

• Safety-critical measurement in I&C systems that monitor coolant temperature, reactor vessel conditions, and other parameters influencing reactor safety.
• Process control within both primary and secondary systems of nuclear power plants, supporting efficient and secure operation.
• Ongoing maintenance and operational assurance, as the standard prescribes in situ testing and documentation procedures, facilitating reliable long-term monitoring.
• Retrofitting and upgrades, where compliance with the updated standard ensures legacy systems meet modern nuclear safety expectations.

Nuclear power operators and equipment manufacturers rely on standardized RTDs for functions such as reactor protection, emergency shutdown systems, and post-accident heat removal, reinforcing overall plant safety.

Related Standards

EN IEC 62397:2026 is part of a broader framework for nuclear safety and instrumentation. It references and aligns with several key standards:

• IEC 60751: Thermometers and platinum temperature sensors - fundamental for the calibration and specification of industrial RTDs.
• IEC/IEEE 60780-323: Qualification of electrical equipment important to safety in nuclear facilities.
• IEC/IEEE 60980-344: Seismic qualification of equipment for nuclear facilities.
• IEC 60068-2-6 / IEC 60068-2-30: Environmental testing including vibration and damp heat.
• IEC 61513: General requirements for I&C systems important to safety in NPPs.
• IEC 63046: General electrical power systems for NPPs.
• IAEA Safety Standards (SSR-2/1, SSG-30, SSG-39): International atomic energy agency guides referenced for harmonized nuclear safety principles.

Adherence to EN IEC 62397:2026 ensures compliance with global nuclear safety standards, supporting regulatory acceptance and reliable operation in high-stakes environments.