Joseph A. Naser

Modernizing and Maintaining Instrumentation and Control Systems in Nuclear Power Plants

Abstract Deregulation of the electric utilities has made a major impact on nuclear power plants. To be competitive, more emphasis is being put on cost-effective production of electricity with a more critical look at whether a system should be modernized due to obsolescence, reliability, or productivity concerns. Instrumentation and control (I&C) systems play an important role in reducing the cost of producing electricity while maintaining or enhancing safety. Systems that are well designed, reliable, enhance productivity, and are cost-effective to operate and maintain can reduce the overall costs. Modern technology with its ability to better provide and use real-time information offers an effective platform for modernizing systems. At the same time, new technology brings new challenges and issues, especially for safety systems in nuclear power plants. To increase competitiveness, it is important to take advantage of the opportunities offered by modern technology and to address the new challenges and issues in a cost-effective manner. The Electric Power Research Institute (EPRI) and its member utilities have been working together with other members of the nuclear industry since 1990 to address I&C modernization and maintenance issues. The EPRI I&C Program has developed a life-cycle management approach for I&C systems that involves the optimization of maintenance, monitoring, and capital resources to sustain safety and performance throughout the plant life. Strategic planning methodologies and implementation guidelines addressing digital I&C issues in nuclear power plants have been developed. Work is ongoing in diverse areas to support the design, implementation, and operation of new digital systems. Technology transfer is an integral part of this I&C program.

Evaluation of RETRAN-02 Options with Peach Bottom Data

The RETRAN-01 system thermal-hydraulics analysis code has been used to simulate the Peach Bottom Unit 2 boiling water reactor (BWR) turbine trip tests. Since these studies have been performed, a second version of the code, RETRAN-02, has been developed and released. The RETRAN-02 code has a number of physical models that did not exist in RETRAN-01. These include slip between phases, subcooled voiding, special steam separator, one-dimensional kinetics, and iterative numerics models. The new models that exist in RETRAN-02 allow a more realistic modeling of the physical phenomena that occur, in particular, in a BWR. The effect of these new models is studied through the analysis of one of the Peach Bottom turbine trip tests. Each models effect is easily observed since the models are applied one at a time. It was demonstrated that if the same options are used in both RETRAN-01 and RETRAN-02, essentially the same results are obtained. This is important because of the large amount of validation that has been performed with RETRAN-01. The results using the new models demonstrate that they are capable of more realistically describing the physical phenomena that occur during a turbine trip in a BWR.

Analysis of Pressurized Water Reactor Anticipated Transient Without Scram Transients with RETRAN-02

This paper describes the analysis of a loss of feedwater (LOFW) ATWS on a U-tube PWR (pressurized water reactor). The capabilities of the RETRAN-02 code have been extended to allow it to perform pressurized water reactor anticipated transient without scram (ATWS) calculations. A loss-of-feedwater ATWS was performed with RETRAN-02 and compared with vendor calculations with excellent agreement. 2 refs.

RETRAN analysis of the Peach Bottom turbine trip tests

The RETRAN system thermal-hydraulics analysis code has been used to model a series of three turbine trip tests. These three tests were performed at the Peach Bottom Unit 2 (PB2) boiling water reactor (BWR) during April 1977. A detailed description of this analysis including sensitivity studies using RETRAN-01 has been issued by the Electric Power Research Institute (EPRI). Additional analysis using RETRAN-02 is described. 8 refs.