IEC 61497:1998 pdf download – Nuclear power plants – Electrical interlocks for functions important to safety – Recommendations for design and implementation

IEC 61497:1998 pdf download – Nuclear power plants – Electrical interlocks for functions important to safety – Recommendations for design and implementation.
IEC 61497 provides recommendations br the design and implementation 01 electrical interlocks used actively or passively to prevent unsafe conditions or to ensure specific sate conditions and states during the operation of nuclear power plants. Safety system interlocks are covered by standards for safety systems.
This standard gives design, reliability and test criteria arising from the consideration of interlocks important to safety in accordance with IEC 61226, It uses categories A, B and C as defined by that document. II takes into account the interlock safety significance and functions. and the role 0$ the operator in some interlocks.
Guidance is given on redundancy and on diversity of equipment for implementing interlocks, where high availability or Integrity Is involved, or where common mode lailure may limit reliability.
The use of computer-based equipment for interlock functions is discussed, and recommendations for diversity are given. Requirements for software and for verification and validation are given by reference to fEC 60880.
The pfovision of test facilities is discussed together with self-testing and self-monitoring methods.
The system of interlocks for a specific function Includes the sensors of plant stale (e.g.. measuring devices and limit switches), the interlock and control power supplies, the control and instrumentation equipment providing the particular logic function for prevention or limitation of operation, and the cables, electromechanical features, key control and administrative control associated with the function.
2 NormatIve references
The following normative documents contain provisions which, through reference In this text. constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currenily valid International Standards.
IEC 60231A’1969. First supplement to IEC 60231:1967, General priAciples of nuclear reactor ins trumentation ,I
lEG 60617-12:1997, Graphical symbols for diagrams — Part 1 2: Binary logic elements
IEC 60812:1985. AnalysIs techniques for system reliability — Procedure for failure mode and
effects analysis (FMEA)
IEC 60880 1986, Software for computers in the safety systems of nuclear power stations
IEC 60987; 1989, Programmed digital computers important to safety for nuclear power stations
IEC 61225:1993, Nuclear power plants — Instrumentation and control systems important for safely — Requirements for electrical supplies
IEC 61226:1993, Nuclear power plants — Instrumentation and control systems important for safety — Classification
lEG 81500:1996. Nuclear power plants — Instrumentation and control systems Important to safety — Functional requirements for multiplexed data transmission
IAEA 50-C-D(Rev. 1 ):1 988. Code on the safety of nuclear power plants — Design
IAEA 50-SG-D3:1980, Protection system and related features in nuclear power plants
IAEA 50-SG-D8:1 985, Safety-related instrumentation and control systems for nuclear power
plants
3 Definitions and abbreviations
3.1 DefInitions
For the purpose of this International Standard, the following definitions apply.
3.1.1
availability
Iraction of time that a system Is actually capable of performing its mission (IAEA 50-SG-D8)
3.1.2
category
safety category as A. B, C or unclassified, defined for the function. system or equipment by classification to IEC 61226
3.1.3
channel
separate path along which information flows through a redundant or distributed system, That path may also require redundancy (adapted from IEC 61500).
3.1.4
diversity
existence of two or more different ways or means of achieving a specified objective. Diversity is specifically provided as a defense against common mode failure It may be achieved by providing systems that are physically different from each other, or by functional diversity, where similar systems achieve the specified objective in different ways (see clause 3 of IEC 61226).