Emergency and Preventive Reactor Protection Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 309

Figure 2. Structure and configuration of SHC E&PRP set

◦ From seismic sensors (earthquake
detection with intensity above the
limit);

• Receiving of commands from the control

keys located in the main control room and
the emergency control room, that initiate:
◦ Accident and protection systems
actuation;
◦ Return to normal position after emer-
gency protection actuation;
◦ Display switch-of that indicates the
actuation reason.

• Computation of parameter values which

cannot be measured directly, for example,
diferences of irst and second circuits
saturation temperatures (further - design
values);

• Storing of data:

◦ On control parameters limits;
◦ On conditions of normal and safe
power unit performance;
◦ On signal forming algorithms, initi-
ating actuation emergency and pre-
ventive reactor protection in case of
violation of these conditions or ex-
ceeding the set limits;

Additional functions of signal forming cabi-
nets:

• Continuous monitoring of technical state

condition of its hardware, adjacent equip-
ment and signal and message lines;

• Forming and sending to workstation of

digital messages which contain informa-
tion on the current monitoring parameters
values, initial events, state of technological
equipment and diagnostics results;

• Forming in accordance with the algorithm

and sending to cross output cabinet of
control signals (commands ERP or PRP1,
PRP2) in case of detection of any emergen-
cy or preventive reactor protection actua-
tion conditions (depending on conditions
caused system actuation, the control signal
delay and / or automatic signal withdrawal
after the set time delay are provided);

• Setting and changing of the control param-

eters limits.

Structural scheme of signal forming cabinet
are shown at Figure 3.