Jung-Taek Kim

Development of advanced I&C in nuclear power plants: ADIOS and ASICS

In this paper Automatic Startup Intelligent Control System (ASICS) that automatically controls the PWR plant from cold shutdown to 5% of reactor power and Alarm and Diagnosis-Integrated Operator Support System (ADIOS) that is integrated with alarms, process values, and diagnostic information to an expert system focused on alarm processing are described. Nuclear Power Plant is manually controlled from cold shutdown to 5% according to the general operation procedures for startup operation of nuclear power plant. Alarm information is the primary sources to detect abnormalities in nuclear power plants or other process plants. The conventional hardwired alarm systems, characterized by one sensor-one indicator may lead the control room operators to be confused with avalanching alarms during plant transients. ASICS and ADIOS are designed to reduce the operator burden. The advances in computer software and hardware technology and also in information processing provide a good opportunity to improve the control systems and the annunciator systems of nuclear power plants or other similar process plants. It is very important to test and evaluate the performance and the function of the computer- or software-based systems like ASICS and ADIOS. The performance and the function of ASICS and ADIOS are evaluated with the real-time functional test facility and the results have shown that the developed systems are efficient and useful for operation and operator support.

Development of an Alarm-Cause Path Tracking System

Alarm system is very important for the safety of nuclear power plant. When alarm, operator refers alarm logic diagrams to identify the logical relationship between the alarm and its causes. This paper propose a system which tracks the logical path between alarm and its causes on the alarm logic diagrams of Wolsung nuclear power plant unit 3 & 4. And a grammar for the validation of logic diagrams expressed in 2 dimensional strings, and logical operations with 3 states to track alarm-cause paths and to display the state of logics are proposed. This system is on operation at Wolsung site.

Pipe Corrosion Analysis by Time-Frequency Distribution and Ridge Pattern

A time-frequency analysis (TFA) is applied to the analysis of the vibration signals from a pipe where some chemical corrosion is likely to occur by an acidic material being mixed in the coolant of nuclear power plants. The spalling out of internal material pieces by the so-called flow-accelerated corrosion (FAC) is expected to change the structural vibration of a local point in the pipe, but this effect is too tiny to be recognized in the result of the Fourier transform. From the analysis by TFA, it is identified that the TFA can provide important information such as the amplitude fluctuations in the instantaneous frequency of each characteristic frequency. The analysis results show that the peak or ridge pattern of the TFA varied according to the status of the chemical corrosion within the pipe

Expert System-Based Implementation of Failure Detection

In light of the need to improve MMIS of NPPs, the advanced I&C research team of KAERI has embarked on developing an Alarm and Diagnosis-Integrated Operator Support System, called ADIOS. ADIOS was composed of two modules such as alarm process module and fault diagnostic module. The alarm process module can offer key alarms to operator using dynamic alarm filtering methods and the fault diagnostic module was able to diagnose the component failure caused by a sensor fault and a hardware fault. ADIOS has been built in an object-oriented AI environment of G2 expert system software tool. In the G2 environment, every alarm and diagnostic component have been treated as an object of class. The attributes of each alarm object include activation status, alarm message, process value, activated time, priority, acknowledgment state, interlocked equipment and caused alarm. If an alarm is activated, its icon color on an overview process mimic diagram changes corresponding to its priority, which can be set initially or determined dynamically by reasoning rules and procedures. The process conditions, such as plant or equipment status and correlated alarms’ states have determined the priority of the activated alarm and the fault diagnostic condition. The knowledge base and the inference engines of ADIOS have been constructed by process analysis of the plant and discussion with operators and nuclear plant experts.