Developing A Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic: Quarterly Progress Report (Aug. 01 – Oct. 31, 2003)

The experimental setup designed and manufactured in UNLV was shipped to LANL in early Aug. One student has been working in LANL to conduct the experiment since then. In the meantime, one new Ph. D. student has started to run the simulation for transport in oxygen mixing. In Oct., a professional has been hired to work in both experimental and the theoretical studies pertaining to the proposed work

Developing a Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic

The research objectives of this project were as follows: To generate calibration curves of voltage versus oxygen concentration for the YSZ oxygen sensor system under various temperatures in liquid LBE. To determine the sensor characteristics of the YSZ sensor system. To determine oxygen dissolving rates in LBE under different temperatures in vitro. To study the effects of unwanted electrical conductivity, contributed by the mobility of the electrons at high temperatures, for more accurate oxygen measurement. To study alternative and promising oxygen measuring methods

Developing A Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic: Quarterly Progress Report (July 1 – Sept. 30, 2004)

Dr. Jiang Ma and Mr. Xiaolong Wu worked in LANL between July 1 and Sept. 15 to conduct the experiment. Test of the corrosion of different materials in LBE was performed. The influence of the process of gas introduction to the LBE was studied. Data analysis work was performed based on accumulated data. In the same time, progress has been made in the simulation for transport in oxygen mixing, and one paper was presented in a conference. Another paper was composed and submitted to IEEE International Symposium of Circuits and Systems for the track Chemical Sensors. Preparation of a paper regarding to the RGA analysis for the calibration of oxygen sensor is on the way

Developing A Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic: Quarterly Progress Report (Jan. 01 – March. 31, 2005)

We performed data analysis on the data collected from LANL test loop. One student was been hired to perform the data analysis. A new proposal is submitted to TRP program. We have one paper accepted for publication in International Journal of Heat and Mass Transfer, and another paper accepted for oral presentation by IEEE International Symposium of Circuits and Systems for the track Chemical Sensors. A manuscript regarding to the RGA analysis for the calibration of oxygen sensor is on the way

Calibration of YSZ Sensors for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic

Although liquid lead-bismuth eutectic (LBE) is a good candidate for coolant in the subcritical transmutation blanket, it is known to be corrosive to stainless steel, the material of the carrying tubes and containers. Such longterm corrosion problem can be prevented by producing and maintaining a protective oxide layer on the exposed surface of stainless steel. For this purpose, it is required to accurately control the concentration of oxygen dissolved in LBE. Currently, YSZ (Yttria Stabilized Zirconia) oxygen sensors, based on an existing automotive oxygen sensor, with molten bismuth saturated with oxygen as the reference, have been selected for oxygen-concentration measurement. The oxygen concentration difference across the solid electrolyte and the resultant oxygen ion conduction inside the electrolyte establishes an electromagnetic force that is used to measure the ppb level concentration of oxygen dissolved in liquid LBE. A set of calibration curves of voltage vs. temperature ranging from 300 0C to 500 0C under various oxygen concentrations in liquid LBE for the YSZ oxygen sensor has been obtained and is presented in this paper. Although the current calibration strategy using the direct injection of hydrogen and oxygen is still inadequate to determine the oxygen concentration in the system, we have found a good candidate for our purpose, which is varying hydrogen to water steam ratio in the system

Developing a Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic

Lead-bismuth eutectic (LBE) is a candidate as a spallation target in sub-critical transmutation systems and as a coolant in nuclear programs. One of the primary concerns with LBE systems is the corrosion of stainless steel, the primary structural material used in nuclear systems. To mitigate this problem, trace levels of oxygen can be introduced into the system, causing the formation of a protective oxide layer at the interface between the LBE and steel. To protect the steel components, this oxide layer must be properly maintained. However, too much oxygen will produce unwanted oxide precipitation within the coolant and elsewhere in the system. With the current generation LBE systems, the stability of the oxide layer on the internal components is maintained through controlling the temperature of the system and the dissolved oxygen concentration in the coolant. Controlling these two operating parameters is the key to operating LBE systems and minimizing corrosion. While the temperature of the system is easy to measure, the concentration of dissolved oxygen in the LBE is more complicated. Yttria-stabilized zirconia (YSZ) solid-electrolyte oxygen sensing systems are currently employed by Los Alamos National Laboratory (LANL) scientists to measure oxygen levels in the Delta Loop, an engineering-scale LBE experimental system. By measuring the voltage difference across the YSZ sensor, the oxygen concentration in test solutions can be determined relative to that in the reference solutions (the potentiometric method). The theoretical model for calculating oxygen concentration based on voltage measurements from YSZ sensors in static conditions is well understood. The real world performance of these systems, however, is less predictable. The primary goal of this research project is to examine the major factors impacting the performance of YSZ oxygen sensing systems. The research effort will serve to fill the gaps in the current sensor calibration/validation work and further the development of new sensors for oxygen concentration measurement in a nuclear environment. Ultimately, acquired data will lead to the full implementation of the instrumentation in the system. Through this work, the research group will also generate the calibration curves for the YSZ sensors over various temperature ranges

Developing A Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic: Quarterly Progress Report (Nov. 01 – Jan. 31, 2002)

The design of the new apparatus for oxygen measurement/calibration has been completed. This new apparatus shall be of great importance for the UNLV researchers to conduct the research work in the campus

Developing A Sensing System for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic: Quarterly Progress Report (Aug. 01 – Oct. 31, 2002)

After two month intensive work in LANL, some preliminary sensor calibration curves have been obtained. Further data analysis shall be performed to assess the theoretical and measured data. Also, a new experimental apparatus shall be designed and located in UNLV to continue the left work. Technical Progress: • A set of calibration curves of voltage vs. temperature ranging from 3000C to 5000C under various oxygen concentrations in liquid LBE for the YSZ oxygen sensor has been obtained and has been reported in one paper. • A meeting with LBE committee and other faculty members in AAA projects was organized to discuss our new experimental apparatus design. • We have identified the major components/parts to be incorporated in our sensor experimental apparatus, and we have finalized the geometries of some of the parts. This newly-designed system shall be accommodated in HRC center. • We started to use FEMLAB free version to do simulations for oxygen concentration distributions in our setup due to stirring