DS/EN IEC 63046:2021

Nuclear power plants - Electrical power system - General requirements

This document:*• provides requirements and recommendations for the overall Electrical Power System. In*particular, it covers interruptible and uninterruptible Electrical Power Systems including*the systems supplying the I&C systems;*• is consistent and coherent with IEC 61513. Like IEC 61513, this document also highlights*the need for complete and precise requirements, derived from the plant safety goals.*Those requirements are prerequisites for generating the comprehensive requirements for*the overall Electrical Power System architecture, and for the electrical power supply subsystems;*• has to be considered in conjunction with and at the same level as IEC 61513. These two*standards provide a complete framework establishing general requirements for*instrumentation, control, and Electrical Power System for Nuclear Power Plants.*This document establishes:*• the high level specification and requirement to implement a suitable Electrical Power*System in a NPP that supports reactor systems important to safety. It also enables*electrical energy production providing the transmission grid with active and reactive power*and electro-mechanical inertia;*• the relationships between:*– the plant safety requirements and the architecture of the overall Electrical Power*System and its sub-systems (see Figure 1) including:*a) the contribution to the plant Defence in Depth;*b) the independency and redundancy provisions;*– the electrical requirements and the architecture of the Electrical Power System and its*sub-systems;*– the functional requirements and the architecture of the Electrical Power System and its*sub-systems;*– the requirements associated with the maintenance strategy and the architecture of theElectrical Power System and its sub-systems;*• the design of Electrical power sub-systems (e.g. interruptible and uninterruptible);*• the requirements for supporting systems of Electrical Power System (HVAC, I&C, etc.);*• the Electrical Power System life-cycle framework.*This document does not cover the specification of:*• I&C systems;*• the transmission lines connecting to substations outside the NPP;*• electrical equipment requirements already defined in the industrial IEC standards;*• electrical power for security systems (e.g., fences, surveillance systems, entrance*control);*• lighting and socket facility.*This document does not consider power production requirements.This figure provides only an example. Various possible arrangements of buses, loads, generators and*interconnections would meet the requirements of SSR-2/1. Furthermore, many elements of the plant system, such*as buses that are not important to safety and direct current power systems, are not shown. This figure is intended*only to represent the relationship between the elements of the plant power systems that are within the safety*classification and the preferred power supply. The elements of the preferred power supply that are not within the*bounds of the important to safety power supply are outside the scope of the plant safety classification. The system*elements included in the important to safety power supplies will differ according to plant design and the*classification methods applied in different States. The classification methods are held by IEC 61226. Some plant*designs may not require safety standby power sources. All nuclear power plants are expected to have safety direct*current power supplies.*1.2 Application: new and pre-existing plants*This document is applicable to the Electrical Power System of new nuclear power plants and*upgrading or back fitting of existing plants.*For existing plants, only a subset of requirements may be applicable and this subset should*be identified at the beginning of any project.*1.3 Framework*This document consists of six normative clauses (an overview is provided in Figure 2):*– Clause 6 addresses the identification of requirements;*– Clause 7 addresses the design of the electrical architecture;*– Clause 8 addresses the sub-system requirements;– Clause 9 addresses the verification;*– Clause 10 addresses the overall integration and commissioning;*– Clause 11 addresses the overall operation and maintenance.*1.4 Interaction with level 2 standards*This document shall permit an electrical designer to establish the list of requirements*applicable for the design.*It also provides the different provisions applicable for the different requirements.*These provisions will be applied to the different type of power networks (sub-system):*• interruptible AC power network;*• uninterruptible power network.*Moreover, other transverse level 2 standards will define requirements applicable to electrical*architecture definition.*The nuclear standards linked with the safety provisions (such as safety classification,*separation, qualification or surveillance testing, etc.) are considered as input data for this*document.