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Title: A survey of techniques for corrosion monitoring

Abstract

Corrosion monitoring techniques have improved with advances in instrumentation technology and corrosion research. Older techniques, such as coupon immersion, generally provide historical information. The new electrochemical techniques, which have not been used widely at SRS, allow on-line monitoring and correlation with process changes. These techniques could improve the corrosion assessment of the waste tanks to be used for In-Tank Precipitation and Extended Sludge Processing. A task was initiated to place an electrochemical probe into tank 48 for testing the utility of this technique for waste tank applications.

Authors:
Publication Date:
Research Org.:
Westinghouse Savannah River Co., Aiken, SC (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10153395
Report Number(s):
WSRC-TR-92-472
ON: DE93012131
DOE Contract Number:
AC09-89SR18035
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Oct 1992
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 22 GENERAL STUDIES OF NUCLEAR REACTORS; CORROSION; MONITORING; ELECTROCHEMISTRY; RADIOACTIVE WASTE STORAGE; TANKS; HIGH-LEVEL RADIOACTIVE WASTES; SAVANNAH RIVER PLANT; SLUDGES; PH VALUE; ELECTRIC CONDUCTIVITY; NONDESTRUCTIVE TESTING; CORROSION PRODUCTS; FLUID FLOW; PRODUCTION REACTORS; STAINLESS STEEL-304L; NITRATES; 360105; 052002; 052001; 220600; CORROSION AND EROSION; WASTE DISPOSAL AND STORAGE; WASTE PROCESSING; RESEARCH, TEST, TRAINING, PRODUCTION, IRRADIATION, MATERIALS TESTING REACTORS

Citation Formats

Mickalonis, J.I.. A survey of techniques for corrosion monitoring. United States: N. p., 1992. Web. doi:10.2172/10153395.
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Mickalonis, J.I.. A survey of techniques for corrosion monitoring. United States. doi:10.2172/10153395.
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Mickalonis, J.I.. Thu . "A survey of techniques for corrosion monitoring". United States. doi:10.2172/10153395. https://www.osti.gov/servlets/purl/10153395.
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@article{osti_10153395,
title = {A survey of techniques for corrosion monitoring},
author = {Mickalonis, J.I.},
abstractNote = {Corrosion monitoring techniques have improved with advances in instrumentation technology and corrosion research. Older techniques, such as coupon immersion, generally provide historical information. The new electrochemical techniques, which have not been used widely at SRS, allow on-line monitoring and correlation with process changes. These techniques could improve the corrosion assessment of the waste tanks to be used for In-Tank Precipitation and Extended Sludge Processing. A task was initiated to place an electrochemical probe into tank 48 for testing the utility of this technique for waste tank applications.},
doi = {10.2172/10153395},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Oct 01 00:00:00 EDT 1992},
month = {Thu Oct 01 00:00:00 EDT 1992}
}
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Technical Report:
View Technical Report (0.99 MB)
DOI:  10.2172/10153395
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  • Corrosion monitoring techniques have improved with advances in instrumentation technology and corrosion research. Older techniques, such as coupon immersion, generally provide historical information. The new electrochemical techniques, which have not been used widely at SRS, allow on-line monitoring and correlation with process changes. These techniques could improve the corrosion assessment of the waste tanks to be used for In-Tank Precipitation and Extended Sludge Processing. A task was initiated to place an electrochemical probe into tank 48 for testing the utility of this technique for waste tank applications.

  • ; ; ; ...
    'This report evaluates the first year''s results of the research on the development of advanced electrochemical sensors for use in high subcritical and supercritical aqueous environments. The work has emphasized the designing of an advanced reference electrode, and the development of high-temperature pH and redox sensors for characterizing the fundamental properties of supercritical aqueous solutions. Also, electrochemical noise sensors have been designed for characterizing metal/water interactions, including corrosion processes. A test loop has been designed and constructed to meet the expected operation conditions. The authors have also developed an approach to define a practical pH scale for use with supercriticalmore » aqueous systems and an operational electrochemical thermocell was tested for pH measurements in HCl + NaCl aqueous solutions. The potentials of the thermocell for several HCl(aq) solutions of different concentrations have been measured over wide ranges of temperature from 25 to 400 C and for flow rates from 0.1 to 1.5 cm min{sup -1} . The corresponding pH differences ({Delta}pH) for two HCl(aq) concentrations in 0.1 NaCl(aq) solution have been experimentally derived and thermodynamically analyzed. Their first experimental measurements, and subsequent theoretical analysis, clearly demonstrate the viability of pH measurements in high subcritical and supercritical aqueous solutions with a high accuracy of \2610.02 to 0.05 units.'« less

  • ; ;
    'This report evaluates the two years results of the research on the development of advanced electrochemical techniques for use in supercritical water oxidation (SCWO) environments. The SCWO technology was found to be a promising approach to treat a variety of hazardous wastes. However, the corrosion processes in the SCWO reactors is still a problem for further development of this technology. The authors have developed a flow-through electrochemical cell (FTEC) which allows us to monitor the corrosion process in real time at temperatures up to 500 C and pressures up to 400 bar. The FTEC consists of a flow-through Ag/AgCl externalmore » pressure-balanced reference electrode, a flow-through platinum hydrogen electrode, an yttria-stabilized zirconia pH sensor and an electrochemical noise sensor. The new FTEC has been designed to serve as a measurement vessel for the high temperature and high pressure circulation once-through flow loop and titanium alloy was chosen as the construction material. The FTEC, shown schematically in Figure 1, is used for the experiments. Two HPLC pumps are employed in the system, one for pumping the reaction solution through the loop and the other for pumping the reference solution through the reference electrode. The system pressure is sustained as a constant via a back pressure regulator. The temperature was measured using a thermocouple installed at the center of the FTEC. Because many physico-chemical processes, including corrosion, are sensitive to the pH, the measurement and control of pH is very important for the high temperature SCWO environment. The authors have measured the potentials of the FTEC for several HCl(aq) + NaCl(aq) solutions of different concentrations of HCl(aq) and derived the corresponding pH differences ({Delta}pH) over a wide range of temperatures at pressure around 350 bar. Comparison of the experimentally derived and theoretically calculated DpH values presented in Figure 2 clearly demonstrates the ability to measure pH with a high accuracy (better than \2610.05 pH units). This result also shows the viability of the developed FTEC as a versatile potentiometric system for use at supercritical temperatures. During the next year of the project they will address the problem of electrochemical noise measurements and monitoring corrosion processes that occur on metallic materials exposed to super critical water.'« less

  • ;
    This project is developing sensing technologies and corrosion monitoring techniques for use in super critical water oxidation (SCWO) systems to reduce the volume of mixed low-level nuclear waste by oxidizing organic components in a closed cycle system where CO2 and other gaseous oxides are produced, leaving the radioactive elements concentrated in ash. The technique uses water at supercritical temperatures under highly oxidized conditions by maintaining a high fugacity of molecular oxygen in the system, which causes high corrosion rates of even the most corrosive resistant reactor materials. This project significantly addresses the high corrosion shortcoming through development of (a) advancedmore » electrodes and sensors for in situ potentiometric monitoring of pH in high subcritical and supercritical aqueous solutions, (b) an approach for evaluating the association constants for 1-1 aqueous electrolytes using a flow-through electrochemical thermocell; (c) an electrochemical noise sensor for the in situ measurement of corrosion rate in subcritical and supercritical aqueous systems; (d) a model for estimating the effect of pressure on reaction rates, including corrosion reactions, in high subcritical and supercritical aqueous systems. The project achieved all objectives, except for installing some of the sensors into a fully operating SCWO system.« less

  • Super Critical Water Oxidation (SCWO) is a promising technology for destroying highly toxic organic waste (including physiological agents) and for reducing the volume of DOE's low-level nuclear waste. The major problem inhibiting the wide implementation of SCWO is the lack of fundamental knowledge about various physico-chemical and corrosion processes that occur in SCW environments. In particular, the lack of experimental techniques for accurately monitoring important parameters, such as pH, corrosion potential and corrosion rate, has severely hampered the development of a quantitative understanding of the degradation of materials in this extraordinarily aggressive environment. Accordingly, the principal objective of the presentmore » program has been to develop new, innovative methods for accurately measuring parameters that characterize corrosion processes under super critical conditions.« less