Regional Basic Professional Training Course in Korea

❙ 635 ❙
10-A. Limiting Conditions for Operation
pressure transients in LOCA and steam pipe rupture where not exceeding design pressure
is shown in view of the interaction of the different safety control features (release of
emergency feedwater, main feedwater isolation, etc.). These studies appear in the safety
report.
10.2.2.2. Measures carried out on the boiler
Respect for the above criteria involves first of all, status monitoring of the facility. Figure
10.l shows the main measures carried out and which form the safety system source of
information.
10.2.2.3. Main safety channels
From the measures that have just been given, different safety channels are formed. Two
types of safety channels can be differentiated:
The specific protections are characterized by the fact that they monitor only one of
the parameters characterizing the plant status. These protections, by virtue of their
simplicity, have a slow response time. They intervene during rapid accidents
characterized by a sudden change in just one of these parameters.
They are therefore associated with a particular event type (loss of primary flow, rod
drop, etc.),
The generic protections are characterized by the fact that they monitor the basic
parameters of reactor status and are not appointed to the protection of a particular
type of accident. They intervene during slower transients during which these
parameters vary simultaneously.
Emergency shutdown is brought about when the thermal power (ΔT) exceeds a limit
power (ΔT set point), which is variable and calculated continuously from measurements
of primary coolant temperature (T), primary coolant pressure (P), primary coolant pump