The effects of notches on the fatigue life of components have long been investigated and methods a proposed that semi-empirically account for the notch. They are concentrated on estimation of the fatigue limit stress. but the effect of the notches on fatigue crack initiation has been less investigated due to lack of suitable non-destructive tools. Despite the qualitative studies on the size effects on fatigue crack initiation, few quantitative studies can be found in literature since identification of fatigue crack initiation, which often occurs inside notched coupons, has so far been an arduous task. We propose a critical Bragg edge mapping experiment at EnginX to identify the onset of fatigue crack initiation in round notch bars with varying crack lengths. We will complement this work with neutron tomography and digital volume correlation, should IMAT be ready to receive users.