Application of guidelines on digital I&C upgrades

Nuclear utilities are upgrading their existing instrumentation and control (I&C) systems. The upgrades are being driven primarily by the growing problems of obsolescence, difficulty in obtaining parts, and increased maintenance costs of existing systems. There also is great incentive to take advantage of modern digital technologies which offer potential performance and reliability improvements. A guideline to assist utilities in these upgrades has been prepared by a committee of EPRI, NUMARC and industry representatives. The committee worked with NRC to reach a consensus approach for design, implementation, and licensing of digital upgrades, which is the basis for the EPRI guideline. This paper briefly recaps the background for development of the guideline, and it gives a brief overview of the approach and content of the document. An update on the status of its use by the industry and acceptance by the NRC is provided. Finally, some lessons learned from recent upgrades and applications of the EPRI guidance are discussed