In-situ measurements of stress during thermal shock in clad pressure vessel steel using synchrotron X-ray diffraction

•Synchrotron X-ray diffraction was used to measure the transient strain in the material during a thermal shock event on cladded steels.•Stress intensity factor was deduced which showed its maximum occurring less than a second after the thermal shock event.•Despite detailed calibration of the simulations, the experiment and simulation did not match fully.•Further calibration could have been done to match the experiment and finite element, but this is contrary to industrial practice.•This demonstrates the need for detailed experiments.