為了進行超臨界狀態下金屬材料的電化學行為分析並獲取相關的電化學參數，除了建立一套適用於溫度374 °C以上與壓力22.1 MPa以上的模擬超臨界水循環系統外，穩定且耐用的參考電極是不可或缺的。本論文主要研究目的在於發展高溫專用的Ag/AgCl參考電極以及Zr/ZrO2所製成的參考電極，並將其應用於超臨界水環境中，進行304L不鏽鋼電化學腐蝕電位(ECP)之量測，觀察其ECP在純水中隨溫度變化之情形。測試結果發現在常溫下，氧化鋯管所製作成的Ag/AgCl參考電極經過72小時靜置時間後與商用Ag/AgCl參考電極同在飽和KCl溶液中的電位值差異皆小於10 mV以內，證明此高溫專用的Ag/AgCl參考電極在常溫環境下是可正常操作。後續在次臨界環境下及超臨界環境下進行不同溫度，溶氧濃度8.3 ppm下，304L不鏽鋼試片和Inconel 625合金進行ECP量測，量測溫度由300℃~600℃，結果顯示發現在次臨界環境下電位趨勢將隨著溫度升高而上升，然而在超臨界環境下則出現截然不同之電位趨勢，進入超臨界後電位反而隨著溫度上升而劇烈下降。此外在溫度385℃、400℃下改變溶氧環境進行量測，由除氧、300 ppb、1 ppm、8.3 ppm、32 ppm下量測304L不鏽鋼和Inconel 625合金之ECP，在超臨界環境下低溶氧濃度環境之ECP的改變相較於高溶氧濃度環境是較為劇烈的。最後，利用Ag/AgCl電極成功找出Zr/ZrO2電極在不同溫度下之轉換為標準氫電位之校正值。

A lasting and sustainable reference electrode is indispensable to analyzing the electrochemical behaviors of metal materials under supercritical state and identifying the related electrochemical parameters. Another technique is to simulate a supercritical water (SCW) circulation system in which the temperature and pressure is greater than 374 ℃ and 22.1 MPa. This study uses Ag/AgCl reference electrodes and Zr/ZrO2 reference electrodes to measure the electrochemical corrosion potential (ECP) of 304L stainless steel in a SCW environment. Experiment results show that at room temperature, under saturated potassium chloride solution, the potential difference between Ag/AgCl reference electrodes made of Zirconium dioxide tubes and commercial Ag/AgCl reference electrodes after 72 h is less than 10 mV, proving that the former are functional at room temperature. Afterwards we measure the ECP of 304LSS and Inconel 625 specimens under 8.3ppm of dissolved oxygen while changing the test temperature from 300℃ to 600℃. As a result the ECP tend to increase with elevated temperature at subcritical environment, but decrease severely with elevated temperature at supercritical environment. In addition, a test including 304LSS and Inconel 625 specimens at constant temperature of 385℃ and 400℃ while changing the dissolved oxygen from deaerated, 300ppb, 1ppm, 8.3ppm, 32ppm was also conducted. The outcome shows that under supercritical environment, ECP changes much heavily in low dissolved oxygen condition than in high dissolved oxygen. At last, we successfully discover the alignment value for Zr/ZrO2 reference electrode to convert its value into SHE value under different temperature with the aid of Ag/AgCl reference electrode.

參考文獻
1. http://www.grida.no/climate/ipcc_tar/slides/index.htm.
2. 經濟部能源局, 能源產業經濟白皮書. 經濟部, Editor 2012.
3. 謝得志, ''核能溝通''. 清華大學演講, 4/3/2009.
4. Buongiorno, J. and P. MacDonald, Supercritical water reactor (SCWR). Progress Report for the FY-03 Generation-IV R&D Activities for the Development of the SCWR in the US, INEEL/Ext-03-03-01210, INEEL, USA, September, 2003.
5. MacDonald, P.E., Supercritical Water Reactor (SCWR)-Survey of Materials Research and Development Needs to Assess Viability, 2003, Idaho National Laboratory (INL).
6. 梁明在, 超臨界水發電機組的發展與未來趨勢.
7. Was, G., et al., Corrosion and stress corrosion cracking in supercritical water. Journal of Nuclear Materials, 2007. 371(1): p. 176-201.
8. Kritzer, P., Corrosion in high-temperature and supercritical water and aqueous solutions: a review. The Journal of supercritical fluids, 2004. 29(1): p. 1-29.
9. K. Johnston, C.H., Am, Inst. Chem. Eng. J. 33, (1987) 2007.
10. T.K. Yeh , M.Y.W., H.M. Liu and M. Lee MODELING COOLANT CHEMISTRY IN A SUPERCRITICAL WATER REACTOR. TopSafe Conference Helsinki, Finland, April 22-26, 2012.
11. Forum, G.I.I., GIF R&D Outlook for Generation IV Nuclear Energy Systems. 21 August 2009.
12. Khartabil, H., SCWR: Overview. GIF Symposium, Paris, France, 9-10 September, 2009.
13. MacDonald, P.E., Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production, Nuclear Energy Research Initiative Project 2001-001, Westinghouse Electric Co. Grant Number: DE-FG07-02SF22533, Final Report, 2005, Idaho National Laboratory (INL).
14. Cook, W.G. and R.P. Olive, Pourbaix diagrams for the iron–water system extended to high-subcritical and low-supercritical conditions. Corrosion Science, 2012. 55: p. 326-331.
15. Cook, W.G. and R.P. Olive, Pourbaix diagrams for the nickel-water system extended to high-subcritical and low-supercritical conditions. Corrosion Science, 2012. 58: p. 284-290.
16. Cook, W.G. and R.P. Olive, Pourbaix diagrams for chromium, aluminum and titanium extended to high-subcritical and low-supercritical conditions. Corrosion Science, 2012. 58: p. 291-298.
17. K. Ishida, M.T., Y. Wada,N. Ohta, M. Aizawa, DEVELOPMENT OF REFERENCE ELECTRODE USING ZIRCONIUM AS ELECTRODE POLE TO MEASURE ELECTROCHEMICAL CORROSION POTENTIAL IN HIGH TEMPERATURE PURE WATER. 8th Int'l Radiolysis, Electrochemistry & Materials Performance Workshop, October 8, 2010.
18. M. Navas, M.D.G.B., Behaviour of reference electrodes in the monitoring of corrosion potential at high temperature. Nuclear Engineering and Desgin, 1997.
19. Lin, C., et al., Electrochemical potential measurements under simulated BWR water chemistry conditions. Corrosion, 1992. 48(1): p. 16-28.
20. Greeley, R.S., et al., ELECTROMOTIVE FORCE STUDIES IN AQUEOUS SOLUTIONS AT ELEVATED TEMPERATURES. I. THE STANDARD POTENTIAL OF THE SILVER-SILVER CHLORIDE ELECTRODE1. The Journal of Physical Chemistry, 1960. 64(5): p. 652-657.
21. Niedrach, L.W. and W.H. Stoddard, Monitoring pH and corrosion potentials in high temperature aqueous environments. Corrosion, 1985. 41(1): p. 45-51.
22. Leibovitz, J., In-Plant Measurements of Electrochemical Potentials in BWR Water. 1984: Electric Power Research Institute.
23. Weber, M.E.I.a.J.E., Electrochemical Potential Measurements in a Boiling Water Reactor. EPRI NP-3362, (Nov. 1983).
24. Indig, M. and A. McIlree, High temperature electrochemical studies of the stress corrosion of type 304 stainless steel. Corrosion, 1979. 35(7): p. 288-295.
25. Hishida, M., Electrochemical Approach to Stress Corrosion Cracking in BWR Pipes. Spring 1985: p. No. 151, p.13.
26. Lvov, S.N., H. Gao, and D.D. Macdonald, Advanced flow-through external pressure-balanced reference electrode for potentiometric and pH studies in high temperature aqueous solutions. Journal of Electroanalytical Chemistry, 1998. 443(2): p. 186-194.
27. Niedrach, L.W., Use of a High Temperature pH Sensor as a “Pseudo‐Reference Electrode” in the Monitoring of Corrosion and Redox Potentials at 285° C. Journal of the Electrochemical Society, 1982. 129(7): p. 1445-1449.
28. Niedrach, L. and W. Stoddard, Corrosion Potentials and Corrosion Behavior of AISI 304 Stainless Steel in High-Temperature Water Containing Both Dissolved Hydrogen and Oxygen. Corrosion, 1986. 42(12): p. 696-699.
29. Macdonald, D.D., S. Hettiarachchi, and S.J. Lenhart, The thermodynamic viability of yttria-stabilized zirconia pH sensors for high temperature aqueous solutions. Journal of Solution Chemistry, 1988. 17(8): p. 719-732.
30. Y. Wada et al., J.N.S., Technol., (2007): p. 44, p.1448.
31. al., Y.J.K.e., Corros. (2005): p. 61, p.889.
32. Macdonald, D., Viability of hydrogen water chemistry for protecting in-vessel components of boiling water reactors. Corrosion, 1992. 48(3): p. 194-205.
33. Revie, H.H.U.R.W., Corrosion and Corrosion Control. p. Chapter 7.
34. Morash, K., RDSaunders, CHBevilacqua, ACLight, TS, Measurement of the resistivity of ultrapure water at elevated temperatures. Ultrapure Water, 1994. 11(9): p. 18-26.
35. Uchida, S., Y. Morishima, and T. Hirose, Effects of Hydrogen Peroxide on Corrosion of Stainless Steel (VI) Effects of Hydrogen Peroxide and Oxygen on Anodic Polarization Properties of Stainless Steel in High Temperature Pure Water. Journal of NUCLEAR SCIENCE and TECHNOLOGY,Vol. 44, No. 5,, 2007: p. 44: p. 758-766.
36. 廖宥甯, 應用於超臨界水循環系統之耐高溫參考電極的研發. 清華大學, 2011.