Going from analog to digital - Radiated emissions performance of a nuclear plant control system from 10 kHz to 6 GHz

Nuclear power plants (NPPs) in the United States have been upgrading their instrumentation and control (I&C) equipment from analog to digital systems over the past 10 to 15 years. Upgrades have been occurring on the plant floor for I&C systems including generator controls, turbine supervisory controls, and chiller controls as well as for plant control systems in control rooms. Because of the increased focus by utilities and the US Nuclear Regulatory Commission (NRC) on safety and efforts to eliminate plant electromagnetic interference (EMI) events, electromagnetic compatibility (EMC) is still a growing concern. Because of the heightened concern regarding EMI and the growing use of GHz-speed digital equipment and wireless devices in nuclear plants and the critical nature of EMI-related plant events with increasing digital upgrades, utilities are taking proactive steps in characterizing critical EMC environments and engaging in practices to enhance plant EMC. One important step is to determine changes in radiated emissions levels in control rooms where more digital upgrades are planned. The migration from analog to digital equipment in control rooms and other plant areas warrants the need to investigate the emissions characteristics of changing electromagnetic environments (EMEs). These changing environments are being characterized through Electric Power Research Institute (EPRI) research by conducting point-of-installation (POI) emissions measurements before analog systems are removed, and then again after digital systems are installed and operational. This paper presents the first-of-its-kind analysis of a complete set of radiated emissions measurement data from 10 kHz to 6 GHz as part of a plant control system upgrade inside a control room to replace an analog control system (ACS) with a digital control system (DCS) for one operating unit of a nuclear plant in the United States.