53 research outputs found
Application of the leak-before-break concept to the primary circuit piping of the Leningrad NPP
No full textA two-year Finnish-Russian cooperation program has been initiated in 1995 to demonstrate the applicability of the leak-before-break concept (LBB) to the primary circuit piping of the Leningrad NPP. The program includes J-R curve testing of authentic pipe materials at full operating temperature, screening and computational LBB analyses complying with the USNRC Standard Review Plan 3.6.3, and exchange of LBB-related information with emphasis on NDE. Domestic computer codes are mainly used, and all tests and analyses are independently carried out by each party. The results are believed to apply generally to RBMK type plants of the first generation
A computing systems for LBB considerations
No full textA computing system has been developed at VTT Energy for making efficient leak-before-break (LBB) evaluations of piping components. The system consists of fracture mechanics and leak rate analysis modules which are linked via an interactive user interface LBBCAL. The system enables quick tentative analysis of standard geometric and loading situations by means of fracture mechanics estimation schemes such as the R6, FAD, EPRI J, Battelle, plastic limit load and moments methods. Complex situations are handled with a separate in-house made finite-element code EPFM3D which uses 20-noded isoparametric solid elements, automatic mesh generators and advanced color graphics. Analytical formulas and numerical procedures are available for leak area evaluation. A novel contribution for leak rate analysis is the CRAFLO code which is based on a nonequilibrium two-phase flow model with phase slip. Its predictions are essentially comparable with those of the well known SQUIRT2 code; additionally it provides outputs for temperature, pressure and velocity distributions in the crack depth direction. An illustrative application to a circumferentially cracked elbow indicates expectedly that a small margin relative to the saturation temperature of the coolant reduces the leak rate and is likely to influence the LBB implementation to intermediate diameter (300 mm) primary circuit piping of BWR plants
Bench-KJ: Benchmark on Analytical Calculation of Fracture Mechanics Parameters KI and J for Cracked Piping Components — Progress of the Work
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