Application of “Leak Before Break” Assessment for Pressure Tube in Delayed Hydride Cracking
Gintautas Dundulis*, Albertas Grybėnas**, Vidas Makarevicius**,
and Remigijus Janulionis*
*Laboratory of Nuclear Installation Safety, Lithuanian Energy Institute, Breslaujos str. 3, LT-44403 Kaunas, Lithuania
**Laboratory of Material Research &Testing, Lithuanian Energy Institute, Breslaujos str. 3, LT-44403 Kaunas, Lithuania
The Ignalina NPP uses an RBMK-1500 reactor, which is graphite-moderated with a water-cooled reactor core. The fuel cell assembly in the center of the moderator column consists of a pressure tube containing the fuel element assembly and through which coolant flows. Pressure tubes are made of Zr-2.5Nb zirconium alloys. Hydrogen absorbed by the zirconium alloy during corrosion is one of the factors determining pressure tube lifetime. If the pressure tube hydrogen concentration exceeds solubility limitations, delayed hydride cracking (DHC) may occur. Hydrides forming under certain conditions may reduce resistance to brittle fracture. Here we evaluate hydride influence on pressure tube fracture and the application of leak before break (LBB) for tubes with DHC. Deterministic analysis employing LBB concept used experimental data. Deterministic LBB analysis confirms that pressure tubes comply with LBB requirements.
-  M. S. Ali, “An Historical Survey of Leak-Before-Break in Nuclear Plant Piping,” Power-Gen Worldwide, March 2010.
-  G. Wilkowski, “Leak-Before-Break: What Does It Really Mean?,” J. of Pressure Vessel Technology, Vol.122, Issue 3, pp. 267-272, 2000.
-  B. A. Cheadle, A. Celovsky, M. Ghafoor, and W. Butt, “Assessment of the Integrity of KANUPP Fuel Channels,” CNA/CNS Conference, Fredericton, New Brunswick 1996 June 9 to 12, AECL-11710, p. 15, 1996.
-  M. P. Puls, B. J. S. Wilkins, G. L. Rigby, J. K. Mistry, and P. J. Sedran, “A probabilistic method for leak-before-break analysis of CANDU reactor pressure tubes,” Nuclear Engineering and Design, Vol.185, pp. 241-248, 1998.
-  C. Z. Serpan Jr, M. E. Mayfield, and J. Muscara, “US Nuclear regulatory commission research for primary system integrity regulations,” Nuclear Enginering and Design; Vol.171, pp. 1-14, 1997.
-  L. Xie, “The effect of characteristic crack sizes on the leak-beforebreak case of pressure vessels and piping with multiple cracks,” Int. J. of Pressure Vessels and Piping, Vol.76, pp. 435-439, 1999.
-  B. Ghosh, S. K. Bandyopadhyay, H. G. Lele, and A. K. Ghosh, “Estimation of crack opening area for leak before break analysis of nuclear reactor system,” Nuclear Engineering and Design, Vol.239, pp. 327-337, 2009.
-  J. W. Kim, “A practical application of an evaluation model for the restraint effect of pressure-induced bending on a plastic crack opening,” Int. J. of Pressure Vessels and Piping. Vol.85, pp. 557-568, 2008.
-  D. L. Rudland, G. Wilkowski, and P. Scott, “Effects of crack morphology parameters on leak-rate calculations in LBB evaluations,” Int. J. of Pressure Vessels and Piping, Vol.79, pp. 99-102, 2002.
-  L. Xie, “Multi-crack growth/coalescence simulation and its role in passive component leak-before-break concept,” Nuclear Engineering and Design, Vol.194, pp. 113-122, 1999.
-  Y. W. Park, S. S. Kang, and B. S. Han, “Structural integrity assessment of pressure tubes for Wolsong Unit 1 based on operational experiences,” Nuclear Engineering and Design, Vol.212, pp. 41-48, 2002.
-  Y. W. Park and Y. K. Chung, “Leak-before-break assessment of CANDU pressure tube considering leak detection capability,” Nuclear Engineering and Design, Vol.191, pp. 205-216, 1999.
-  G. Dundulis, A. Grybenas, A. Klimasauskas, V. Makarevicius, and R. Levinskas, “Ageing Assessment of RBMK – 1500 Fuel Channel in Case of Delayed Hydride Cracking,” Mechanika ISSN 1392-1207, No.1 (57), pp. 5-11, 2006.
-  V. Makarevicius, A. Grybenas, and R. Levinskas, “Controlled Hydriding of Zr-2,5%Nb Alloy by Thermal Diffusion,” Materials Science (Medziagotyra), Vol.7, No.4, pp. 249-251, 2001.
-  R. R. Hosbons, P. H. Davies, M. Griffiths, S. Sagat, and C. E. Coleman, “Effect of long-term irradiation on the fracture properties of Zr-2.5Nb pressure tubes. Zirconium in the Nuclear Industry,” 12th Int. Symposium, ASTM STP 1354, G. P. Sabol and G. D. Moan (Eds.), ASTM, West Conshohocken, PA, pp. 122-138, 2000.
-  J. Y. Oh, I. S. Kim, and Y. S. Kim, “A Normalization Method for Relationship between Yield Stress and Delayed Hydride Cracking Velocity in Zr – 2.5 Nb alloys,” J. of Nuclear Science Technology, Vol.37, No.7, pp. 595-600, 2000.
-  IAEA-TECDOC-1410, “Delayed hydride cracking in zirconium alloys in pressure tube nuclear reactors,” Final report of coordinated research project, 1996-2002, Vienna, 2004.
-  Ignalina NPP Unit 2 Safety Analysis Report, “Determination of Structural Integrity of Technological Channels During Operation. Final Report,” OIPab2-0745-50, Kaunas: Lithuanian Energy Institute, 126 p., 2002.
-  C. Coleman, M. Griffiths, V. Grigoriev, V. Kiseliov, B. Rodchenkov, and V. Markelov, “Mechanical Properties of Zr-2.5Nb Pressure Tubes Made from Electrolytic Powder,” J. of ASTM Int., Vol.4, No.10. Paper ID JAI101111, 2007. Available online at www.astm.org..
-  M. Daunys, R. Dundulis, A. Grybėnas, and P. Krasauskas, “Hydrogen influence on mechanical and fracture mechanics characteristics of zirconium Zr–2.5Nb alloy at ambient and elevated temperatures,” Nuclear engineering and design, Vol.238, Iss. 10, pp. 2536-2545, 2008.
-  Int. J. of Pressure Vessels and Piping, R. W. Nichols (Ed.), Vol.32, p. 327, 1988.
-  T. Anderson and L. Fracture, “Mechanics: Fundamentals and Applications,” Boston, CRC Press Inc., -793 p., 1991.
-  P. Andersson, M. Bergman, B. Brickstad, L. Dahlberg, F. Nilsson, and I. Sattary-Far, “A Procedure for Safety Assessment of Components with Cracks – Handbook,” SAQ Kontroll AB, Stockholm, 1996.
-  N. Ghadiali, D. Paul, F. Jakob, and G. Wilkowsi, “SQUIRT (Seepage Quantification of Upsets In Reactor Tubes),” User’s manual. – Columbus: Battelle, 164 p., 1996.
-  F. Axisa, “CASTEM2000; Elements de Theorie et Exemples,” Rapport DMT/96-498, 1996.
-  “Guidance for application of the Leak Before Break concept at Ignalina NPP RBMK-1500 reactors,” VD-E-03-98. – Vilnius: VATESI, 35 p. 1998.
This article is published under a Creative Commons Attribution-NoDerivatives 4.0 Internationa License.