Significance: Jun 30, 2002 Identified By: NRC Item Type: FIN Finding INADEQUATE DIGITAL FEEDWATER SYSTEM DESIGN AND INADVERTENT GROUNDING OF PLANT EQUIPMENT RESULTS IN REACTOR SCRAM A digital feedwater control system design weakness, in conjunction with the inadvertent grounding of a pressure transmitter during an instrument maintenance surveillance, resulted in a manual reactor scram due to in...

This paper uses the linear quadratic Gaussian with loop transfer recovery (LQG/LTR) control system design method to obtain a level control system for a low-pressure feedwater heater train. The control system performance and stability robustness are evaluated for a given set of system design specifications. The tools for analysis are the return ratio, return difference, and inverse return differ...

Thermal nuclear reactor power is typically evaluated with secondary system calorimetric calculations based on feedwater flow rate measurements. The feedwater flow rate should therefore be measured accurately. Venturi meters are currently used to measure the feedwater flow rate in most pressurized water reactors (PWRs). The long-term operation of a nuclear power plant causes a buildup of corrosi...

In this paper, the exergoeconomic analysis was conducted to an existing ultra-supercritical coal-fired power plant in China to understand the cost-formation process, to evaluate the economic performance of each component and to find possible solutions for more cost-effective designs. The total revenue requirement (TRR) and the specific exergy costing (SPECO) methods were applied for economic an...

Assessing the reliability of digital control systems is an important but challenging task. Traditional tools of reliability and risk analysis, such as event and fault trees, have limitations. Some dynamic methods, such as dynamic flowgraph methodology and Markov models, seem to hold promise but evidence of their suitability and utility is still scarce. This report deals with the reliability ass...

Since failure in, damage to, and performance degradation of power generation components in operation under harsh environment of high pressure and high temperature may cause both economic and human loss at power plants, highly reliable operation and control of these components are necessary. Therefore, a systematic method of diagnosing the condition of these components in its early stages is req...

A conventional exergy analysis can highlight the main components having high thermodynamic inefficiencies, but cannot consider the interactions among components or the true potential for the improvement of each component. By splitting the exergy destruction into endogenous/exogenous and avoidable/unavoidable parts, the advanced exergy analysis is capable of providing additional information to c...

Work related to the first-principle modeling of a feedwater heater operating in a coal-fired power unit is presented, along with theoretical discussion concerning its structural simplifications, parameter estimation, and dynamical validation. The objectives of this work are as follows: (i) formulate and deploy a moderately complex first-principle model of a feedwater heater to reproduce operati...

Two dynamic methodologies, dynamic flowgraph methodology (DFM) and the Markov/cellto cell mapping technique (CCMT), are implemented on the benchmark digital feedwater control system (DFWCS) specified in NUREG-6942 (Dynamic Reliability Modeling of Digital Instrumentation and Control Systems for Nuclear Reactor Probabilistic Risk Assessments) [1], to demonstrate how an existing nuclear power plan...