8.9. Although not normally labeled as such, the reactor core is indeed a system, with such components as the fuel assemblies and control ele­ments. Here, we see an example of the need sometimes to define the boundaries of a system arbitrarily since the control elements could be included in the control system.

Reactor coolant system

8.10. Strictly speaking, the reactor coolant system includes those com­ponents associated with the flow of the primary coolant, such as the coolant pumps, pressurizer, and associated piping and valves. However, the reactor vessel and steam generators could also be included arbitrarily.

Instrumentation and control system

8.11. This system includes the following major subsystems:

1. Nuclear instrumentation that indicates power level

2. In-core instrumentation to provide nuclear flux distribution

3. Process instrumentation for nonnuclear measurements in steam system sup­ply components

4. Reactor protection system for initiating safety in response to abnormal conditions (§12.22)

5. Control room (§14.25)

Engineered safeguards system

8.12. Countermeasures in the event of an accident are provided for by this system. Included in this system are several subsystems, such as the safety injection systems, containment sprays, the emergency feedwater system, and other safety features (§12.33 et seq.).

Other systems

8.13. The Nuclear Steam Supply System also includes a number of other subsystems that we need not consider here, such as those for auxiliary fluids, containment, fuel handling, waste management, and chemical control.