Abstract
This paper describes the critical digital review (CDR) procedure, which was developed by Institute of Nuclear Energy Research (INER), and sponsored by Taiwan Power Company (TPC). A preliminary CDR application experience which was performed by INER, is also described in this paper. Currently, CDR becomes one of the policies for digital Instrumentation and Control (I&C) system replacement in TPC. The contents of this CDR procedure include: Scope, Responsibility, Operation Procedure, Operation Flow Chart, CDR review items. The "CDR Review Items" chapter proposes optional review items, including the comparison of the design change, Software Verification and Validation (SV&V), Failure Mode and Effects Analysis (FMEA), Evaluation of Watchdog Timer, Evaluation of Electromagnetic Compatibility (EMC), Evaluation of Grounding for System/Component, Seismic Evaluation, HFE Evaluation, Witness and Inspection, Lessons Learnt from the Digital I&C Failure Events. Since CDR has become a TPC policy, Chin Shan Nuclear Power Plant (NPP) performed the CDR practice of Automatic Voltage Regulator (AVR) digital I&C replacement, even though the project had been on the half way. The major review items of this CDR were: the comparison of the design change, SV&V, FMEA, Evaluation of Watchdog Timer, Evaluation of Electromagnetic Compatibility (EMC), Evaluation of Grounding for System/ Component, Witness and Inspection, Lessons Learnt from the Digital I&C Failure Events. The experience of the CDR showed the importance of preparation of the documents by the vendor. This means the communication with the vendors for the bid preparation is crucial.
