Application of leak-before-break concept to integrity and safety of PWR primary piping with WWER 1000

• Published in: Nuclear engineering and design Vol. 151; no. 2; pp. 409 - 424
• Main Authors: Kiselev, V.A., Rivkin, E.Yu, Smirnov, Yu.I., Sokov, L.M., Sudakov, A.V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.1994
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/0029-5493(94)90185-6

The general methodology and criteria used for the leak-before-break (LBB) concept for the PWR primary circuit with WWER 1000 are described. The application of the LBB concept requires the following additional protections. First, the candidate system should be highly qualified piping, performed in accordance with the applicable regulations and guidelines, carefully screened to verify that they are not subjected to any disqualifying failure mechanism. Therefore the piping service experience and design bases are screened. Next, the analysis of leak-detection capabilities is performed. The postulated crack must be of sufficient size that the resulting leakage will be detected by the leak-detection systems installed. Finally, fracture-mechanics analysis is performed to demonstrate that the crack will not cause pipe rupture even if seismic loads are applied before the flawed section is discovered and repaired. The calculated and experimental results obtained to date are very encouraging and show the applicability of the LBB concept for the PWR primary circuit with WWER 1000.