High Integrity Digital to Analog Converter Recovery Program

This document is a technical report detailing a recovery program for high integrity digital to analog converters (HIDAC) used in the safety systems of a nuclear power plant. The HIDAC units, which had been in service for over 25 years, faced increasing failure rates and were no longer supported by the original manufacturer. The report outlines the multiphase program undertaken by Curtiss-Wright, which included investigative engineering recovery and refurbishment of the HIDAC units. Key findings from the investigation revealed issues such as incomplete product support data, obsolete programmable logic devices, and faults due to semiconductor aging. The recovery actions aimed to enhance reliability and supportability for over 10 years, leading to the development of comprehensive documentation, including parts lists and maintenance procedures. The refurbishment process involved replacing critical components and ensuring the operational integrity of the units through rigorous testing and quality assurance measures.