WG 7

Functional and safety fundamentals of instrumentation, control and electrical power systems

The Working Group WG7 produces and maintains standards and reports on particular aspects of the fundamental principles for instrumentation, control and electrical power systems important to safety for nuclear facilities (i.e. power plant, nuclear fuel cycle and waste facilities).

The standards produced by WG7 will expand the IAEA standards and guidance including:

- SF-1 Fundamental Safety Principles
- SSR-2/1 Safety of NPP – Design
- NS-R-4 Safety of Research Reactors
- NS-R-5 (Rev. 1) Safety of Nuclear Fuel Cycle Facilities
- SSG-30 Safety Classification of SSC in NPP
- INSAG– 10 Defence in Depth in Nuclear Safety

and seek compliance with them.

The standard developed by the working group will also take cognisance of other IAEA guides relevant to instrumentation, control and electrical power systems including:

- SSG-39 Design of I&C Systems for NPPs
- SSG-34 Design of Electric Power Systems for NPP
- SSG-37 Instrumentation and Control Systems and Software Important to Safety for Research Reactors

but will not address detailed design and related matters that are the scope of other SC45A working groups principally WG A3 (I&C systems) and WG A11 (Electrical power systems).

The task thus includes:

• Categorisation of safety functions
• Generic principles of Classification of instrumentation, control and electrical power systems important to safety and functional allocation requirements
• Defence in depth
• Denial of service by single failures
• Defence against Common Cause Failure (including systematic faults) and
the implementation of techniques such as separation, diversity and isolation to achieve independence and protection from internal and external hazards and from random and systematic faults.
• Quantitative reliability evaluation, its assurance by surveillance and proof testing and limitation by consideration of common cause failures and systematic faults.
• Analysis techniques for the identification and treatment of potential random and systematic faults.