British Standards Institution

Nuclear power plants - Instrumentation and control important for safety - Software aspects for computer-based systems performing category B or C functions - CORR: December 31, 2009
 N BS EN 62138

Annotation

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.