Density and distribution of fabrication flaws in the Shoreham reactor vessel

The Pacific Northwest National Laboratory (PNNL) has been conducting a multi-year program for the U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Regulatory Research on the effectiveness of NDE for inspection of nuclear power plants. One task of this program concerns the development of generic flaw density and distribution functions for fabrication flaws in reactor pressure vessels. Reactor pressure vessel material from the cancelled Shoreham nuclear power plant was obtained as a part of a joint program between the NRC, Baltimore Gas and Electric and the Electric Power Research Institute. PNNL has conducted NDE inspections of this material and has estimated the density and distributions of fabrication flaws in this material. This paper discusses these inspections and the results of analyzing this inspection data. More than 4,000 fabrication flaws were detected and are described in this paper.