XI, Appendix VIII, performance demonstration for pressurized water reactor (PWR) thickness reactor pressure vessel (RPV) wall welds. This

demonstration concluded a 5-year program at SWRI to, arguably, prepare for the most difficult performance demonstration requirement ever undertaken. During the 5-year program, several mockups constructed from actual RPV material were designed and fabricated by SWRI, and contained various flaws of sizes and aspect ratios required by Appendix VIII. In order to take maximum advantage of the latitude allowed by Appendix VIII, new techniques were developed and empirically proven and demonstrated that would save time and improve results. The program included development of innovative new search unit designs which significantly enhance flaw detectability and sizing. A new multichannel high performance state-of-the-art ultrasonic (UT) imaging system, the Enhanced Data Acquisition System-II (EDAS^TM-II) was developed during this period and was capable of using the new search unit technology and application techniques to their maximum advantage. This paper discusses the advantages of advanced UT imaging technology to assure the accuracy and high confidence levels required to satisfactorily complete a difficult performance demonstration program. Technical problems relative to application of ultrasonics through weld deposited stainless steel cladding are discussed as well as the empirically developed solutions to these problems. Other areas covered in the paper deal with advanced calibration techniques which depart significantly from classical amplitude-based calibration, and nonamplitude-dependent detection and sizing techniques which assure reliable detection and characterization of flaws.