Abstract
The main standard bases for NPP instrumentation and control (I&C) systems are documents of the International Atomic Energy Agency (IAEA) and International Electrotechnical Commission (IEC). Standards are interconnected through the following: IAEA develops general safety principles for NPP I&C systems, and IEC develops technical requirements that use and specify safety principles. Structures of both bases are considered. IAEA and IEC safety classification principles are described. Classifications of I&C systems and their components are given on the basis of their safety impact. According to IEC, functions to be performed by I&C systems shall be assigned to categories according to their importance to safety. The importance to safety of a function shall be identified by means of the consequences in the event of its failure, when it is required to be performed, and by the consequences in the event of a spurious actuation.
TopBackground
Elaboration of international standards related to NPP I&C began immediately after commissioning of the first NPP. The IEC created a separate technical committee, devoted to NPP I&C, with name “Nuclear Instrumentation” in 1960. One of the first IEC publications – “General principles of nuclear reactor instrumentation” was issued in 1967. IEC understood importance of computer technique for NPP automatics: publication “Application of digital computer to nuclear reactor instrumentation and control” had data 1979. During more than 50 years IEC developed a lot of standards applicable to different types of I&C, to different aspects of NPP I&C design and operation. Special attention is paid to application of computer systems and the latest achievement in information technology.
The IAEA elaborated Codes on safety of NPPs, which related to all NPP systems, including I&C (e.g., “50-C-D. Code on Safety on Nuclear Power Plants. Design” (IAEA, 1988). Special safety guides related exclusively to protection systems and related features IAEA 50-SG-D3 and to safety related instrumentation and control systems IAEA 50-SG-D8 were issued in 1980 and 1984 (IAEA, 1980; IAEA, 1984). IEC and IAEA had close connections in the development of standard base for NPP I&C.
Many countries where NPPs are operated developed their national standard base related to I&C. One of the first American National Standards (based on IEEE Standard 323-1974) was ANSI/IEEE Std.323-1983 “IEEE Standard for Qualifying Class1 Equipment for Nuclear Power Generating Stations” which did not lose its importance for long time. The first USSR Regulation PBYa-04-74 “Rules of NPP Nuclear Safety” which contained requirements on reactor control and protection systems, was issued in 1974.
Ukraine after gaining independence (1991) used to 1999 USSR regulations and standards related to NPP I&C. Ukrainian regulation “NP 306.5.02/3.035-2000. Requirements for nuclear and radiation safety to information and control systems important to safety of nuclear power plants” was issued in 2000 (NP, 2000) and was used to 2015 when was replaced by (NP, 2015).
Key Terms in this Chapter
National Regulatory Authority: Authority designated by government for regulatory purposes for safety assurance.
Regulatory Requirement (Regulations): A requirement which is established by the National Regulatory Authority.
Safety Classification: Differentiation of systems or their components into classes, depending on their impact on NPP safety.
Safety Fundamentals: A document which contains fundamental principles of safety assurance and safety objectives.
Function: Specific purpose or objective to be accomplished, that can be specified or described without reference to the physical means of achieving it.
I&C Systems Important for Safety: I&C systems whose malfunction or failure could lead to undue radiation exposure of the site personnel or member of public, and those I&C systems that prevent anticipated operation occurrences from leading to f unacceptable consequences.
Standard Base: A set of standards/regulations which is established by government or international organizations for specific area of activity.
Category of I&C Functions: Group of I&C functions, defined according to their importance to safety.