BS EN IEC 60709:2019 pdf free.Nuclear power plants – Instrumentation, control and electrical systems important to safety – Separation.
This document applies to I&C and electrical systems of new nuclear power plants and to l&C and electrical upgrading or back-fitting of existing plants. For existing plants see 1.2 and 5.4.
Where independence is required by general safety standards such as IAEA safety guides, IEC 61513 (for l&C), IEC 63046 (for electrical systems) and other project constraints, one aspect of achieving this independence is physical separation and electrical isolation between the systems and their equipment that perform safety functions. This document defines the assessments needed and the technical requirements to be met for l&C and electrical systems, equipment or cables for which separation is required. Those means are to achieve adequate physical separation and electrical isolation between redundant sections of a system and between a higher and lower class systems. This separation is needed to prevent or minimise the impact on safety that could result from faults and failures which could be propagated or affect several sections of a system or several systems.
The requirements for functions, and their associated systems and equipment, to be independent are normally defined in detail in the project documentation; the method of determining and defining these requirements is not the subject of this document.
Following IAEA SSR-2/1 Requirement 21, separation means by physical separation, electrical isolation, functional independence and independence of communication are considered. In this document physical separation and electrical isolation are treated. Functional independence and independence of communication are not considered in this document. More details referring to functional independence, independence from control systems and independence of communication are given in Annex D.
1.2 Application: new and pre-existing plants
This document applies to the I&C and electrical of new nuclear power plants as well as to upgrading or back-fitting of existing plants
For existing plants, only a subset of requirements is applicable and this subset is normally specified and argued at the beginning of any project.BS EN IEC 60709 pdf download.