EN IEC 62138:2019 pdf download

EN IEC 62138:2019 pdf download.NUCLEAR POWER PLANTS – INSTRUMENTATION AND CONTROL SYSTEMS IMPORTANT TO SAFETY – SOFTWARE ASPECTS FOR COMPUTER-BASED SYSTEMS PERFORMING CATEGORY B OR C FUNCTIONS
1 Scope
This document specifies requirements for the software of computer-based instrumentation and control (I&C) systems performing functions of safety category B or C as defined by IEC 61 226. It complements IEC 60880 which provides requirements for the software of computer-based I&C systems performing functions of safety category A. It is consistent with, and complementary to, IEC 61 51 3. Activities that are mainly system level activities (for example, integration, validation and installation) are not addressed exhaustively by this document: requirements that are not specific to software are deferred to IEC 61 51 3. The link between functions categories and system classes is given in IEC 61 51 3. Since a given safety-classified I&C system may perform functions of different safety categories and even non safety-classified functions, the requirements of this document are attached to the safety class of the I&C system (class 2 or class 3). This document is not intended to be used as a general-purpose software engineering guide. It applies to the software of I&C systems of safety classes 2 or 3 for new nuclear power plants as well as to I&C upgrading or back-fitting of existing plants. For existing plants, only a subset of requirements is applicable and this subset has to be identified at the beginning of any project. The purpose of the guidance provided by this document is to reduce, as far as possible, the potential for latent software faults to cause system failures, either due to single software failures or multiple software failures (i.e. Common Cause Failures due to software). This document does not explicitly address how to protect software against those threats arising from malicious attacks, i.e. cybersecurity, for computer-based systems. IEC 62645 provides requirements for security programmes for computer-based systems.
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 animation process by which the behaviour defined by a specification is displayed with actual values derived from the stated behaviour expressions and from some input values [SOURCE: IEC 60880:2006, 3.1 ] 3.2 application function function of an I&C system that performs a task related to the process being controlled rather than to the functioning of the system itself [SOURCE: IEC 61 51 3:201 1 , 3.1 ] 3.3 application software part of the software of an I&C system that implements the application functions Note 1 to entry: Application software contrasts with system software. Note 2 to entry: Application software is plant specific, so it is not to be considered pre-developed software. [SOURCE: IEC 61 51 3:201 1 , 3.2 modified (modified notes to entry)] 3.4 application-oriented language computer language specifically designed to address a certain type of application and to be used by persons who are specialists of this type of application Note 1 to entry: Equipment families usually feature application-oriented languages so as to provide easy to use capability for adjusting the equipment to specific requirements. Note 2 to entry: Application-oriented languages may be used to specify the functional requirements of an I&C system, and/or to specify or design application software. They may be based on texts, on graphics, or on both. Note 3 to entry: Examples: function block diagram languages, languages defined by IEC 61 1 31 -3. Note 4 to entry: See also general-purpose language. [SOURCE: IEC 60880:2006, 3.3 modified (addition of note 4 to entry)]3.6 complexity degree to which a system or component has a design, implementation or behaviour that is difficult to understand and verify [SOURCE: IEC 61 51 3:201 1 , 3.9] 3.7 computer program set of ordered instructions and data that specify operations in a form suitable for execution by a computer Note 1 to entry: This includes traditional programs written in general-purpose languages. This also includes programs written in application-oriented languages. [SOURCE: IEC 60880:2006, 3.1 0, modified (addition of note 1 to entry)]