EN IEC 62138:2019

Nuclear power plants - Instrumentation and control systems important to safety - Software aspects for computer-based systems performing category B or C functions EN IEC 62138:2019

Publication date:   May 18, 2020

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 61226. 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 61513. 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 61513.
The link between functions categories and system classes is given in IEC 61513. 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.