Environmental Engineering Reference
In-Depth Information
Rod Group and Individual Control
On the basis of signals received from two or
three channels, in which specified power unload-
ing conditions were detected, the cross cabinet
generates and delivers to input of three channels
of the actuation system RG&ICS a command PUL.
This command causes reactor power decrease due
to a sequential drop of groups of control rods in
the reactor core with a nominal speed. Informa-
tion about output of a command PUL and state
(availability or inoperability) of each channel is
indicated on an alarm board, placed in MCR.
Common signals of violation of operability and /
or deactivation of any channel, actuation of power
unloading function and equipment state, caused
unloading and of access in any cabinet control
switching of a proper board in MCR.
In case of disconnection of the main equip-
ment, setting of turbine stop valves, disconnection
of the unit from electrical power system, when
unit power exceeds 75% of the nominal value, or
direct input of a command with a key located in
MCR, the cross output cabinet forms (on the basis
of signals received from two or three channels)
and outputs a command of accelerated preventive
protection (APP):
Rod group and individual control is performed
in all modes of power unit operation and also
during scheduled and emergency shutdowns and
influences the process of chain reaction in the
core for keeping the reactor power and / or other
parameters of reactor facility within specified
limits, for power change or transfer of the reac-
tor to a subcritical state. Specified functions are
performed by the rod group and individual control
system (RG&ICS).
During power unit operation, simultaneous
change in the state of several (group) control rods
(group control) or one (any) selected control rod
(individual control) is executed in the core. In
case of scheduled reactor shutdown, performed for
equipment maintenance or nuclear fuel reloading,
all groups of control rods are sequentially inserted
in the core by an operator command that termi-
nates the chain reaction. Emergency shutdown by
a command ERP, received from the emergency
reactor protection system, is executed by discon-
nection of alternating current at inputs of power
electrical supply, from which control rods are fed,
and deenergization of main and standby power
from their drives. This causes control rods' drop
in the core under gravity that suppress the chain
reaction (reactor shutdown).
RG&ICS provides group and individual
control of control rods in automatic and manual
mode. Automatic group control is performed by
commands of the emergency reactor protection
(ERP), preventive reactor protection (PRP1),
accelerated preventive protection (APP), power
unloading and limitation (PUL) and reactor power
control (RPwC).
By operator's commands manual (remote)
group and individual control is performed:
• At inputs of three channels of the actua-
tion system RG&ICS (initiates rapid reac-
tor power decrease due to deenergization
of the main and standby power supply to
all control rods of a preliminary speciied
group and their drop into the core).
• At inputs of TCS (initiates actions causing
proper turbine power decrease).
Simultaneously at outputs of the cross cabinet,
signals form for switching the board in MCR,
initiating actuation of APP and the cause of actua-
tion, are generated. Command APP and the cause
signal are stored at the output of the cross cabinet
until they will be reset by the operator with proper
keys in MCR. Current, diagnostic and archival
information is received by the workstation and
transmitted in CIS of the power unit.
•
Lifting and dropping with a working speed
of any group of control rods or transfer
of groups one after another in a project
sequence.
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