Ming-Huei Chen

Digital Instrumentation and Control Failure Events Derivation and Analysis by Frame-Based Technique

A frame-based technique, including physical frame, logical frame, and cognitive frame, was adopted to perform digital IC and (2) postulated ABWR digital IC and then can take early corrective actions to avoid the system hazard. This paper also discusses the advantage of Simulation-based method, which can investigate more in-depth dynamic behavior of digital I&C system than other approaches. Some unanticipated interactions can be observed by this method.Copyright

The Application of FPGA for Anticipated Transients Without Scram Mitigation System

The digitalized Instrumentation and Control (I&C) system of nuclear power plants (NPP) could provide operator easily Human-Machine Interface (HMI) and more powerful overall operation capability. However, some software errors may cause a kind of Common Cause Failure (CCF). As a consequence, the event of Anticipated Transients Without Scram (ATWS) will occur. In order to assure that the plant can be shutdown safely and to follow the requirements of 10CFR50.62, the utility builds up various ATWS mitigation features in NPP. The features include Fine Motion Control Rod Drive Run In, Alternate Rod Insertion, Standby Liquid Control System, Reactor Internal Pump Trip or Runback, Feedwater Flow Runback and Inhibition of Automatic Depressurization System. This research developed an evaluation method of diverse back-up means for computerized I&C system. A diverse backup of digital I&C system is the most important means to defend against CCF and un-detectable software faults. Institute of Nuclear Energy Research (INER) is developing a computerized I&C test facility, which is incorporated a commercial grade I&C systems with Personal Computer Transient Analyzer (PCTran)/Advanced Boiling Water Reactor (ABWR), a NPP simulation computer code. By taking the technology of Field Programmable Gate Array (FPGA) to implement the methods of ATWS mitigation, the research built up a diverse back-up of digital I&C system to expect to defend against CCF and undetectable software faults. According to the testing and evaluation, the work can be achieved the analysis of Diversity and Defense-in-Depth (D3).© 2010 ASME

Development and D3 Application of ABWR Feedwater System Model

This work developed an Advanced Boiling Water Reactor (ABWR) feedwater pump and controller model, which was incorporated into Personal Computer Transient Analyzer (PCTran)-ABWR, a nuclear power plant simulation code. The feedwater pump model includes three turbine-driven feedwater pumps and one motor-driven feedwater pump. The feedwater controller includes a one-element / three-element water level controller and a specific feedwater speed controller for each feedwater pump. The performance tests, including inadvertent closure of all turbine control valves and one feedwater pump trip at 100% power, demonstrate the feasibility of dynamic response of incorporated model. Furthermore, a diversity and defense-in-depth analysis is performed to demonstrate the feasibility for motor-driven feedwater pump as an Emergency Core Cooling System (ECCS) automatic diverse back-up. In Lungmen Nuclear Power Plant (NPP), a diverse manual initiation means for the High Pressure Core Flooder (HPCF) loop C is designed as the back-up of digitalized Engineered Safety Features Actuation System (ESFAS). If the Motor-Driven Feedwater Pump (MDFWP) can be an automatic digital diverse back-up for ESFAS, Lungmen NPP would be more robust to defend against software common cause failure (CCF).Copyright

Software Safety Application Applied in Nuclear Power Plant-Using Frame-Based Technique to Derive and Analyze Failure Events for Digital and Control System

Techniques for analyzing the safety and reliability of systems which include digital computer are difficult to refer to the intuition. Simulation-based method provides a directly understanding of the dynamic behavior of digital I&C system. Lessons learned from historical accident data are being incorporated into improved prevention, mitigation, and identify hazard. This paper presents and discusses the development of a frame-based technique, including physical frame, logical frame, and cognitive frame, to simulate digital I&C failure events derivation and analysis for generic ABWR. This technique will identify the conflicts among plant status, computer: status, and human cognitive status. In the event derivation, a well-trained operator can take early corrective actions to avoid the system hazard. This paper also discusses the advantage of Simulation- based method, which can investigate more in-depth dynamic behavior of digital I&C system than other approaches. In order to let our experiment be more concrete, we will set up one real simulation platform in the future, and its environmental structure is sketch in the future work of this paper.

Digital Instrumentation and Control Failure Events Derivation and Analysis for Advanced Boiling Water Reactor

This research adopted personal computer transient analyzer-advanced boiling water reactor version (PCTran-ABWR) simulation computer code to analyze the software safety issue for a generic ABWR. A number of postulated instrumentation and control (I&C) system software failure events were derived to perform the dynamic analyses. The basis of event derivation includes the published classification for software anomalies, the digital I&C design data of ABWR, chapter 15 accident analysis of generic safety analysis report (SAR), and the reported nuclear power plant I&C software failure events. For the purpose of enhancing the ABWR major control systems simulation capability, this research incorporated MATLAB into PCTran-ABWR to improve the pressure control system, feedwater control system, recirculation control system, and automated power regulation control system. As a result, the software failure of these digital control systems can be properly simulated and analyzed. Moreover, via an internal tuning technique, the modified PCTran-ABWR can precisely reflect the characteristics of the power-core flow map. Hence, in addition to transient plots, the analysis results can then be demonstrated on the power-core flow map. The case study of this research includes: (1) the software common mode failures analysis for the major digital control systems; and (2) postulated ABWR digital I&C software failure events derivation from the actual happening of non-ABWR digital I&C software failure events, which were reported to Licensee Event Report (LER) of US Nuclear Regulatory Commission (USNRC) or Incident Reporting System (IRS) of International Atomic Energy Agency (IAEA). These events were analyzed by PCTran-ABWR. Conflicts among plant status, computer status, and human cognitive status are successfully identified. The operator might not easily recognize the abnormal condition, because the computer status seems to progress normally. However, a well trained operator can become aware of the abnormal condition with the inconsistent physical parameters; and then can take early corrective actions to avoid the system hazard. This paper also discusses the advantage of simulation-based method, which can investigate more in-depth dynamic behavior of digital I&C system than other approaches. Some unanticipated interactions can be observed by this method