10CFR50.59 Evaluation of a Control System Digital Upgrade at Catawba and McGuire Nuclear Stations

摘要

The control (non-safety related) portion of the Westinghouse 7300 Process Instrumentation and Control System was replaced in 2010 with a modern digital Distributed Control System (DCS) using Emerson/Westinghouse Ovation equipment. Ovation is commercial off-the-shelf (COTS) technology that provides programmable application software in secure open-systems architecture. The W7300 consists of two subsystems, Protection and Control, each of which is further subdivided into four subchannels. The protection subsystem was not replaced, but was affected by the modifications to the control subsystem. The control system collects analog and binary process signals from field-mounted sensors and other control systems, performs signal conditioning and parameter setpoint comparisons, and dispatches the resulting information for control, alarm, and display by various plant instrumentation and control systems. The DCS provides advanced functions commonly found in modern microprocessor-based I&C systems, such as graphical displays, trending, logging, soft controls, complex control algorithms, control algorithm detuning, automatic signal selection of process variables (e.g., median select, 2nd high, or 2nd low), and diagnostic capability for field devices via digital communications. The Ovation platform is extendable, and incorporates interfaces with most widely adopted communications bus standards, allowing it to interface with "smart" technologies (e.g. "HART"). The modifications were performed under 10CFR50.59 and the evaluation was conducted following the relevant guidance in NEI 96-07, Rev. 1 and NEI 01-01. This paper summarizes the 50.59 evaluations and key conclusions.