Nuclear power plants Instrumentation and control important for safety Software aspects for computer-based systems performing category B or C functions
|Publication Date:||1 January 2004|
|ICS Code (Nuclear power plants. Safety):||27.120.20|
This International Standard provides requirements for the software of computer-based I&C systems performing functions of safety category B or C as defined by IEC 61226. It complements IEC 60880 and IEC 60880-2, which provide requirements for the software of computer-based I&C systems performing functions of safety category A.
It is also consistent with, and complementary to, IEC 61513. Activities that are mainly system level activities (for example, integration, validation and installation) are not addressed exhaustively by this standard: requirements that are not specific to software are deferred to IEC 61513.
IEC 61513 defines the safety classes of I&C systems important to safety as follows:
• I&C systems of safety class 1 are basically intended to perform functions of safety category A, but may also perform functions of safety category B and/or C, and non safetyclassified functions;
• I&C systems of safety class 2 are basically intended to perform functions of safety category B, but may also perform functions of safety category C, and non safety-classified functions;
• I&C systems of safety class 3 are basically intended to perform functions of safety category C, but may also perform non safety-classified functions.
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 standard are attached to the safety class of the I&C system.
This standard takes into account the current practices for the development of software for I&C systems, in particular:
• the use of pre-developed software, equipment and equipment families that were not necessarily designed to nuclear industry sector standards;
• the use of dedicated "black-box" devices with embedded software;
• the use of application-oriented
This standard is not intended to be used as a general-purpose software engineering guide. It provides requirements that the software of I&C systems of safety classes 2 or 3 must meet to achieve system nuclear safety objectives.