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Experimental and analytical investigation has been carried out for crackinitiation, crack growth and the fracture behavior of notched elbows to demonstrate the Leak-Before-Break (LBB) concept design criteria for the high energy piping system of NuclearPower Plants. The tests have been carried out on 90o large radius elbows of 219 mm outerdiameter and 15.1 mm nominal thickness with a notch at locations such as crown, intradosand without notch. Initiation of crack has been observed from both the surface of wallthickness at the crown of the elbow. Number of cycles for crack initiation obtainedexperimentally and analytically have been found to compare well. Crack growth and numberof cycles have been obtained experimentally and analytically for a/t <0.6 by evaluating stressintensity factor at the crack tip and the Paris constants obtained from the specimen test.Analytically and experimentally obtained crack growth has been found to compare well. Netsection collapse has been found to be dominant failure mode under monotonic loading in theelbow having through wall crack at the crown.