Shrinkage voids in reactor vessel plate materials

Ultrasonic indications revealed during routine examination of thick plates to be used for a nuclear reactor vessel were found to be the result of a void condition in the plates. A testing program was undertaken to determine the nature of the void condition and its effect on the code acceptability and structural integrity of the vessel. The indications were ultimately characterized as the result of shrinkage voids which occurred during the solidification of the steel in the ingot. Although the shrinkage void condition has no adverse effect on the structural integrity of the vessel, the impact of future ASME Section XI acceptability of the vessel dictated the need for repairs to remove the voids. (author)