Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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The Strength and Fracture Behavior characteristics of Irradiated Zr-2.5Nb CANDU Pressure Tube Materials

Zr-2.5Nb 중수로 압력관의 조사후 강도 및 파괴거동 특성

  • Published : 2001.03.01
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Abstract

The tensile and fracture toughness tests have been conducted to investigate the degradations of mechanical properties induced mainly by neutron irradiations in Zr-2.5Nb CANDU pressure tube materials operated in Wolsung Unit-1. the tests were performed at room, 150, 200, 250, 300 $\^{C}$ for the irradiated and unirradiated specimens in hot cell. The specimens were directly machined from the tube retaining original curvature using specially designed electric discharge machine(EDM). From the tensile tests of the irradiated specimens, it was found that tensile strength was increased and total elongation was decreased compared to those of the unirradiated ones. The active voltages in the fracture toughness tests for the irradiated showed the discontinuous abrupt increases caused by crack jumping in lower temperature. In the crack resistance curves we found the stable crack growth in the unirradiated, whereas the unstable and three crack growth stages in the irradiated specimens due to the accumulated irradiation defects. The various fracture characteristic values in the irradiated are remarkably lower than those of the unirradiated. Through the fractography, we found in the irradiated that smaller dimple and shorter fissures than the unirradiated, and that the fractured surface had three regions that were flat, transition and slant/shear area. These can explain the difference in the crack growth characteristic values of the irradiated and the unirradiated ones.

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References

  1. Ells, C.E., 'The Pressure Tubes in the CANDU Reactors,' AECL-Report, AECL-7344
  2. Pulse, M. P., 'Assessment of Aging of Zr-2.5Nb Pressure Tube in CANDU Reactors,' Nuclear Engineering and Design, Vol. 71, 1977, pp. 137-148 https://doi.org/10.1016/S0029-5493(96)01310-6
  3. 이기순, 1997, '조사공학,' 문경출판사, pp. 119-126
  4. Huang, F. H., 1996, 'Fracture Properties of Irradiated Alloys,' Avante Publishing, pp. 204-206
  5. Cheadle, B. A., Colemann, C. E., Rodgers, D. K., Davies, P. H., Chow, C. K. and Griffiths, M., 1988, AECL-Report, ACEL-9710
  6. Moan, G. D., Colemann, C. E., Rodgers, D. K., and Sagat, S., 1990, 'Leak-Before-Break in the Pressure Tubes of CANDU Reactor,' International Journal of Pressure Vessel and Piping, Vol. 43, pp. 1-21
  7. 박윤원, 강성식, 1999, '월성1호기 압력관 건전성평가,' 제6회 원전기기건전성 Workshop논문집, 한국원자력안전기술원, pp. 161-168
  8. Folias, E. S., 1970, 'On the Theory of Fracture of Curved Sheets,' Engineering Fracture Mechanics, Vol. 2, pp. 151-160 https://doi.org/10.1016/0013-7944(70)90019-6
  9. Dugdale, D. S., 1960, Journal of the Mechanics and Physics of Solids, Vol. 8, pp. 100-104 https://doi.org/10.1016/0022-5096(60)90013-2
  10. 지세환, 김영진, 'CANDU 압력관의 건전성 평가,' 대한기계학회지, 제33권 제5호, 1993, pp. 449-455
  11. Fleck, R. G., Price, E. G. and Cheadle, B. A., 1984, 'Pressure Tube Development for CANDU Reactor,' Zirconium in the Nuclear Industry, ASTM STP 824, pp. 88-105
  12. Davies, P. H., Shewfelt, R. S. W. and Jaevine, A. K., 1995, 'Constraint Effects in Testing Different Curved Geometries of Zr-2.5Nb Pressure Tube Material,' Constraint Effects in Fracture: Theory and Application, ASTM STP 1244, pp. 392-424
  13. OH, Wanho, AHN, Sangbok, KWON, Sangchul, KIM, Youngsuk and LEE, Keysoon, 1999, 'The Development of Electric Discharge Machine for Hor Cell Usages,' Proceedings of the 3-rd JAERI-KAERI Joint Seminar on the PIE Technology, JAERI-Conf 99-009, pp. 188-199
  14. 안상복, 김도식, 송웅섭, 권상철, 김영석, 1999, '조사후 중수로 압력관의 파괴인성 시험 기술 개발,' 제6회 원전기기건전성 Work-shop논문집, 원자력안전기술원, pp. 99-112
  15. KIM, Dosik, AHN, Sangbok, LEE, Keysoon, KIM, Youngsuk and KWON, Sangchul, 1999, 'The Development of Crack Measurement System using the Direct Current Potential Drop Method for Use in the Hot Cell,' Proceedings of the 3-rd JAERI-KAERI Joint Seminar on the PIE Technology, JAERI-Conf 99-009, pp. 140-150
  16. Simpson, L. A., Chow, C. K. and Davies, P. H., 1989, 'Standard Test Method for Fracture Toughness of CANDU Pressure Tubes,' AECL-Report COG-89-110-1
  17. Himbeault, D. D. and Davies, P. H., 1998, 'Instruction to round robin participants,' AECL-Report, COG-98-161-1
  18. Chow, C. K. and Simpson, L. A., 1988, 'Determination of the Fracture Toughness of Irradiated Reactor Pressure Tubes using Curved Compact Specimens,' Eighteenth Symposium, ASTM STP 945, pp. 419-439
  19. Chow, C. K., Coleman, C. E., Hosbons, R. R., Davies, P. H., Griffiths, M. and Choubey, R., 1991, 'Fracture Toughness of Irradiated Zr-2.5Nb Pressure Tubes from CANDU Reactors,' Zirconium in the Nuclear Industry: Ninth International Symposium, ASTM STP 1132, pp. 246-275
  20. Davies, P. H. and Shewfelt, R. S. W., 1996, 'Link Between Results of Small- and Large-Scale Toughness Tests on Irradiated Zr-2.5Nb Pressure Tube Materials,' Zirconium in the Nuclear Industry: Eleventh International Symposium, ASTM STP 1295, pp. 492-517
  21. Paris, P. C., Tada, H. Z. and Ernst, H., 1979, 'The Theory of Instability of the Tearing Mode of Elastic-Plastic Crack Growth,' Elastic-Plastic Fracture, ASTM STP 668, pp. 5-36
  22. Ibrahim, E. F., 1987, 'Mehanical Properties of Cold Drawn Zr-2.5Nb Pressure Tubes After up to 12 Years in CANDU Reactors,' Materials for Nuclear Reactor Core Applications, BNES, London, pp. 73-78
  23. Cupp, C. R., 1961, 'The Effect of Neutron Irradiation on the Mechanical Properties of Zirconium-2.5% Niobium Alloy,' Journal of Nuclear Materials, Vol.6, No.3, pp. 241-255 https://doi.org/10.1016/0022-3115(62)90001-6
  24. Lin, G and Eadie, R. L., 1998, 'Monitoring Crack Advance using Acoustic Emission and Combined Acoustic Emission and Potential Drop in Zr-2.5Nb,' Journal of Testing and Evaluation, Vol. 26, No. 1, pp. 15-25 https://doi.org/10.1520/JTE11965J
  25. 오동준, 안상복, 김도식, 김성수, 김영석, 2000, 'Cold Worked Zr-2.5Nb 압력관의 파괴인성 거동,' 제7회 원전기기건전성 Workshop논문집, 원자력안전기술원
  26. Davies, P. H. and Shewfelt, R. S. W., 2000, 'Size, Geometry and Material Effects in Fracture Toughness Testing of Irradiated Zr-2.5Nb Pressure Tube Material,' Zirconium in the Nuclear Industry: Twelfth International Symposium, ASTM STP 1354, pp. 356-376
  27. Langford, W. J. and Mooder, L. E. J., 1978, 'Fracture Behavior of Zirconium Alloy Pressure Tubes for Canadian Nuclear Power Reactor,' International Journal of Pressure Vessels and Piping, Vol. 6, pp. 275-309 https://doi.org/10.1016/0308-0161(78)90013-3
  28. Cheadle, B. A., Colemann, C. E. and Licht, H., 1982, 'CANDU-PHWR Pressure Tubes; Their Manufacture, Inspection and Properties,' Nucl. Technology, Vol. 57, pp. 413-425
  29. Hutchinson, J. W. and Tvergaard, V., 1989, 'Softening due to Void Nucleation in Metals,' Fracture Mechanics: Perspectives and Directions: Twentieth Symposium, ASTM STP 1020, pp. 61-83
  30. Davies, P. H., Hosbons, R. R., Griffith, M., and Chow, C. K., 1994, 'Correlation Between Irradiated and Unirradiated Fracture Toughness of Zr-2.5Nb Pressure Tubes,' Zirconium in the Nuclear Industry: Tenth International Symposium, ASTM STP 1245, pp. 135-167
  31. Aitchinson, I. and Davies, P. H., 1993, 'Role of Microsegregation in Fracture of Cold- Worked Zr-2.5Nb Pressure tubes,' Journal of Nuclear Materials, Vol. 203, pp. 206-220