Reactor Protection System and Engineered Safeguards System
The reactor protection system (RPS) monitors various inputs related to reactor core operation and shuts the reactor down by tripping control rods if any allowable values are exceeded. In this manner, the RPS protects the integrity of the nuclear fuel, which helps ensure the health and safety of the public. The engineered safeguards (ES) system monitors inputs that would indicate the occurrence of certain design basis events and actuates engineered safety features, such as cooling water injection, to mitigate these events.
The digital upgrade to the RPS system and ES system addresses equipment obsolescence concerns. It also includes system enhancements that include additional ES channels, which provide operational and maintenance benefits. Another major benefit of the RPS system and ES system digital upgrade project is the inclusion of online monitoring and diagnostic capabilities. Online monitoring allows elimination of periodic operator checks of system performance.
Because the RPS and ES systems are safety-related protection systems, NRC review and approval was required. Oconee’s RPS system and ES system digital upgrades will be the first digital systems to receive regulatory approvals in the U.S. An AREVA Teleperm XS system will be used for this upgrade, and NRC approval is expected in 2009; installation is scheduled to begin in 2011.
Water Treatment System
Most of the existing equipment in the water treatment room was designed and built in the 1960s. Many of the water treatment system components are no longer manufactured, and replacement parts are unavailable. Digital modernization of the water treatment system helped ensure a reliable source of plant make-up water for the extended life of the facility. In addition, the water treatment system’s efficiency was improved by the digital modernization.
21st-Century Digital Technology
Workers at ONS are completing a 10-year program to upgrade 1970s-vintage instrumentation and control systems to state-of-the-art digital technology. In doing so, Duke Energy has become an industry leader in addressing the associated technical and regulatory issues. At present, the project team has completed digital upgrades on the integrated control system, the main turbine control system, the control rod drive system, the main generator voltage regulator, the process control system, and the automatic feedwater isolation system. Regulatory approval for digital upgrades to the reactor protection system and the engineered safeguards system is expected this year. Together, these upgrades are successfully addressing long-term plant reliability and original equipment obsolescence issues.
—Angela Neville, JD, is POWER's senior editor.
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