Effects of process-generated hydrogen on RPV walls

The minimum mechanical pressure in a crack in the steel material necessary for crack growth has been found to be in the order of several GPa. As this is indeed the order of magnitude reached for the radiolysis generated hydrogen, one has to consider this growth mechanism. When the cracks can keep growing over several fuel cycles, they might reach a critical size and result in the failure of the RPV. Of course, this must be prevented at all times for safety reasons. Therefore, extra research is necessary. As this text is based on theoretical models and some approximations had to be made, uncertainties are inevitable. To check the validity of these calculations, practical experiments can be developed. These can measure the hydrogen pressure buildup in the steel during typical PWR conditions and accidental conditions. One of the difficulties that has to be overcome is the inaccessability of the actual RPV material from Doel 3 and Tihange 2, as for the structural integrity of the RPVs, one can not cut any piece from the RPV.

97

Made with FlippingBook Publishing Software