The steam generator water level control system,
cabinet
The new SGWLC System overcomes the deficiencies
of the old system:
- Very low accuracy of flow measurements (a proper indication
of flow can be obtained from 25% FS upwards);
- Absence of pressure and the temperature compensation of SF and
FWF measure-ments;
-Valve long response time -full opening/closing -35s to 40s, which
causes problems in maintaining the SG level during some transients;
- Low reliability of the valve position sensors;
- Absence of automatic detection of a transmitter failure;
- Low reliability of transmission of signals from the PI controller
to the valve actuator.
Proposed features
The new system utilizes
- Modern technology, overcoming the identified problems by using
reliable transmitters, triple modular redundancy and automatic
validation facilities;
- Proven microprocessor technology for control functions;
- fast response control valves with adequate
capacity
- automatic control of SG level, from 0% to 100% of the load,
covering also the design transients;
- The equipment is "maintenance free" between refuelling
outages
The system also has the following functions:
-Fault detection and appropriate automatic actions;
- Shrink and swell compensation due to pressure variations;
- Smooth transfer functions when switching from manual to automatic
operating mode or backward;
-Supression of hunting between steam generators
System structure parameters
The system is based on Triple modular redundant
controllerTRICON, ver. 9, class 1E certified. The controller ensures
100% availability, which eliminates stop-pages, caused by system
failure. The powerful processing and data storage capability of
the controller enables flexible andadaptive control algorithm
to be performed. These unique features will allow new diagnostic
and control functions to be integrated in the future. The system
provides sensor dual and triple redundancy, which is disting-uishing
feature, compared to the old control systems. The measurements
of the water level are triple redundant.
Water and steam flows and the pressure on the first stage of the
turbo generators are dual redundant. Special algorithm allows
removal of a failed transmitter and replacement with a new one
online. All transmitters are provided with dual power supply.
The actuators are class 1.The 380V AC Supply to the actuators
is in accordance with the Power supply system in the nuclear unit.
Software
The modern structure of the basic software of
platform is another distinguishing feature of the system. It is
based on the IEC 1131 standard function block programming. The
basic software and the configuring module are proven through thou-
sands of applications, most of them critical process control and
protection applications.It is certified by TUV and has
finished succesfuly the tests for 1E applications, required byNRC.
This truly universal control platform provides
excellent means for developing and applying adaptive algorithms
for this
application. Dual and triple redundancy of the instrumentation,
together with reliable algorithms for assessing and isolating
the bad input signals prevent the system from erroneous control
and indicate the failed transmitter on time, restructure
the control algorithm accordingly and permit replacement of the
failed transmitter online.
Simulating facilities
The simulating facilities, used for development,
were imple-
mented, in two directions:
- Static testing
- Dynamyc testing
The dynamic simulator contains the models
of:
Six steam generators and the associated equipment, including:
- The nuclear reactor
- The primaru coolant loops and
- The corresponding controllers.
Reference for this product
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