Award Date

5-2010

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Electrical Engineering

Department

Electrical and Computer Engineering

First Committee Member

Yingtao Jinag, Chair

Second Committee Member

Jian Ma

Third Committee Member

Biswajit Das

Fourth Committee Member

Mei Yang

Graduate Faculty Representative

Hui Zhao

Number of Pages

87

Abstract

Accurate measurement of coolant flow rate is essential for determining the maximum power required by the nuclear plant operation and critical for monitoring its operation safety. However, no practical off-the-shelf flowmeter is available to satisfy all the pressing multidimensional operation requirements (i. e., high temperature, high irradiation, and high corrosion). This work thus deals with the development of a new flowmeter for nuclear power plant/reactor process-monitoring and real time analysis; this proposed flowmeter shall be able to continuously conduct robust measurements under extremely harsh environment with high irradiation, high pressure, high temperature and corrosive media. We investigate a transit-time based flow rate measurement which is used in such environment. The transit time of a thermal signal travels along with a liquid flow can be obtained using a cross correlation method. This transit-time-based flowmeter using thermocouples with grounded stainless steel shielding is by far the most robust and reliable solution to measure the flow rate in a harsh environment typically seen in a nuclear reactor. In practice, cross correlation calculation tends to produce flat peak plateau or multiple peaks, leading to a significant error in peak detection. To overcome this problem, in this work, an Auto-Adaptive Impulse Response Function estimation (AAIRF) technique is introduced and a significantly narrower peak is shown theoretically and also verified experimentally. In addition, we show that more accurate results can be obtained if moving average filter based cross correlation function (MAFCCF) is combined with AAIRF. Also in this work, we investigate a few important practical problems related to negative delays and sampling frequencies of the data acquisition. The second part of this work deals with the calibration of the developed flowmeter which was mentioned above. To commission the flowmeter, calibration process is applied by comparing the reading measurements with a standard flowmeter measurement. In this work, this process is performed in an in house developed water-based test apparatus with a developed transit-time based flowmeter based on the measurement and processing of correlated thermal signals. In this system, we have observed that the accuracy of the measured flow is restricted to the time response of the thermocouples. In addition, since the flow rate is inversely proportional to estimated time delay, high flow rates measurement like 5 gpm (gallon per minute) requires large transit-time span that can not be achieved from a limited physical system dimensions. These problems are investigated through this work.

In the final part of this work, as the ultrasonic flow measurement technologies including transit-time and Doppler effect technologies are usually used in harsh environments, we study these methods with intensive simulations.

Disciplines

Electrical and Electronics | Nuclear Engineering

File Format

pdf

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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