IEC 60744-2018 pdf download.Nuclear power plants – Instrumentation and control systems important to safety – Safety logic assemblies used in systems performing category A functions: Characteristics and test methods.
This document provides requirements and recommendations for the design, construction and test of safety logic assemblies used in safety systems to perform category A safety functions (in accordance with IEC 61 226).
Safety logic assemblies include logic such as the hardwired logic assembly interfacing computer-based systems to switchgear, actuators or contactors to provide trip or engineered safety feature actuations. Safety logic assemblies are significant parts of a safety system and may include voting logic between redundant channels. This document provides a general description of safety logic assemblies for safety actuators control.
The principles to meet dependability objectives are presented. The main features relating to the design requirements are described and explained.
Various tests and their requirements are given in order to validate the design (including the qualification tests), the manufacturing and the correct installation on site. Annex A (informative) gives a list of possible applications of safety logic assemblies. Annex B (normative) suggests a list of possible hardwired technologies with their respective requirements to design safety logic assemblies. Annex C (informative) gives explanations on dependability and its attributes to improve reliability and to reduce the final risk which compromises the safety and the availability of the NPP.
The scope of this document does not address the design of a protection system, it covers only the technological and architectural solutions required to design a safety logic assembly.
The design of safety systems using safety logic assemblies is covered by IEC 61 51 3. The detailed and specific functions implemented in a safety logic assembly strongly depend on the design of each reactor and are not addressed in this document. As this document is focused on I&C part of the system, the final voting logic made with power breakers is excluded from the scope of this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60255 (all parts), Measuring relays and protection equipment
IEC 60671 , Nuclear power plants – Instrumentation and control systems important to safety – Surveillance testing
IEC 60709, Nuclear power plants – instrumentation and control systems important to safety – Separation
IEC/IEEE 60780-323, Nuclear facilities – Electrical equipment important to safety – Qualification
IEC 6081 2, Analysis techniques for system reliability – Procedure for failure mode and effects analysis (FMEA)
IEC 60964, Nuclear power plants – Control rooms – Design
IEC 60965, Nuclear power plants – Control rooms – Supplementary control room for reactor shutdown without access to the main control room
IEC 60980, Recommended practices for seismic qualification of electrical equipment of the safety system for nuclear generating stations
IEC 61 000 (all parts), Electromagnetic compatibility (EMC)
IEC 61 225, Nuclear power plants – Instrumentation and control systems important to safety – Requirements for electrical supplies
IEC 61 226, Nuclear power plants – Instrumentation and control systems important to safety – Classification of instrumentation and control functions
IEC 61 227, Nuclear power plants – Control rooms – Operator controls
IEC 61 51 3, Nuclear power plants – Instrumentation and control for systems important to safety – General requirements for systems
IEC 62003, Nuclear power plants – Instrumentation and control important to safety – Requirements for electromagnetic compatibility testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 availability
ability of an item or a system to be in a state to perform a required function under given conditions at a given instant of time or over a given time interval, given that the necessary external resources are provided.IEC 60744 pdf download.