Nuclear power plants – Instrumentation and control important to safety – General requirements for systems
|Publication Date:||1 August 2011|
|ICS Code (Nuclear power plants. Safety):||27.120.20|
I&C systems important to safety may be implemented using conventional hard-wired equipment, computer-based (CB) equipment or by using a combination of both types of equipment (see Note 1). This International Standard provides requirements and recommendations (see Note 2) for the overall I&C architecture which may contain either or both technologies.
This standard highlights also the need for complete and precise requirements, derived from the plant safety goals, as a pre-requisite for generating the comprehensive requirements for the overall I&C architecture, and hence for the individual I&C systems important to safety.
This standard introduces the concept of a safety life cycle for the overall I&C architecture, and a safety life cycle for the individual systems. By this, it highlights the relations between the safety objectives of the NPP and the requirements for the overall architecture of the I&C systems important to safety, and the relations between the overall I&C architecture and the requirements of the individual systems important to safety.
The life cycles illustrated in, and followed by, this standard are not the only ones possible; other life cycles may be followed, provided that the objectives stated in this standard are satisfied.
NOTE 1 I&C systems may also use electronic modules based on complex electronic components such as ASICs or FPGA. Depending on the scope and functionality of these components, they may be treated according to the guidance for conventional electronic equipment, or similar to CB equipment. A significant part of the guidance for CB equipment is also applicable to the design of equipment with complex electronic components, including e.g. the concepts of re-using pre-existing designs, and the evaluation of design errors in software or complex hardware designs.
NOTE 2 In the following, "requirement" is used as a comprehensive term for both requirements and recommendations. The distinction appears at the level of the specific provisions where requirements are expressed by "shall" and recommendations by "should".