BS 4877:2025

Nuclear reactor instrumentation and control. Code of practice. | Status: Current

1 Scope This British Standard provides recommendations and guidance for the design and safety assurance of instrumentation and control (I&C) systems and equipment for nuclear power plants. This British Standard covers the I&C systems and equipment required for reactor safety and protection, automatic control and other instrumentation and information functions. Recommendations and guidance are also provided for the main and supplementary control rooms, and for the power supplies to the I&C systems.

NOTE 1 This British Standard presents the key principles that apply to the design and safety assurance of these I&C systems. A comprehensive list of the relevant National and International Standards that apply to I&C systems and equipment of nuclear power plants is given in Annex A.

The scope of the I&C systems and equipment covered by this British Standard includes:

1. a) sensors and the measurement of plant variables;
2. b) the reactor safety and protection system;
3. c) nuclear power plant instrumentation;
4. d) plant control systems;
5. e) information display facilities;
6. f) power supplies for the I&C systems; and
7. g) communication systems.

This British Standard does not include recommendations for:

1. 1) I&C for refuelling systems and related facilities;
2. 2) the emergency control centre;
3. 3) the technical support centre and the off‑site support facilities;
4. 4) radiological risks; and
5. 5) commercial or managerial matters.

NOTE 2 In order to cover the scope of I&C systems and equipment listed in a) to g), this British Standard is organized into the following clauses:

1. a) general I&C design principles;
2. b) I&C systems;
3. c) reactor plant instrumentation;
4. d) secondary circuit, turbine and electrical systems;
5. e) detailed design recommendations for specific instrumentation; and
6. f) list of all relevant National and International Standards (Annex A).