IEC 60709:2018

Overview

IEC 60709:2018 - Nuclear power plants - Instrumentation, control and electrical power systems important to safety - Separation defines principles and generic criteria for the separation of instrumentation & control (I&C) and electrical systems whose functions must be independent for safety. The standard applies where independence is required because systems contribute to: redundant or diverse safety groups; different defence‑in‑depth levels; differing safety classes; or interactions with non‑classified (NC) systems. It also covers temporary installations that are part of safety‑important I&C and electrical systems (for example, auxiliary equipment used during commissioning or mobile power supplies).

This edition introduces significant technical changes: it explicitly includes separation requirements for electrical systems important to safety, provides generic separation criteria for both I&C and electrical systems, and aligns scope and terminology with recent revisions of IAEA documents, broadening the aspects of separation addressed.

Key Topics

• Separation principle for safety‑important systems: requirements to ensure independence between redundant or diverse safety equipment and between safety classes.
• Generic separation criteria: high‑level, applicable rules for designing physical and functional separation of I&C and electrical systems important to safety.
• Inclusion of electrical systems: extension of separation requirements beyond I&C to electrical power systems that are important to safety.
• Temporary and mobile installations: guidance on when and how temporary equipment (commissioning auxiliaries, mobile generators) must meet separation considerations.
• Alignment with IAEA guidance: terminological and conceptual alignment to facilitate regulatory and international consistency.

Applications

• Design and verification of separation schemes in new and existing nuclear power plants.
• Engineering specifications for redundant and diverse safety groups and inter‑system independence.
• Procurement and commissioning criteria for temporary electrical and I&C equipment used during tests, maintenance or plant modifications.
• Input to safety cases and regulatory submissions demonstrating that separation provisions meet international expectations.
• Basis for site layout, cable routing, segregation, and protective measures that prevent common‑cause or cascading failures between safety systems.

Who uses this standard

• Nuclear I&C and electrical engineers designing safety systems
• System integrators and plant contractors responsible for separation and redundancy
• Safety assessors, licensing engineers and regulatory bodies reviewing separation measures
• Commissioning teams and maintenance planners managing temporary installations and mobile supplies

Related standards

IEC 60709:2018 is intended to be used alongside national regulations and relevant IAEA safety publications. It provides generic, practical criteria that complement system‑specific standards and regulatory requirements for nuclear safety separation.

Keywords: IEC 60709:2018, separation, nuclear power plants, I&C, electrical systems important to safety, defence in depth, safety classes, temporary installations, IAEA.