Learn How TVA Uses ETAP Real-Time to Monitor the Nuclear Power Plant Auxiliary Power Systems

What are the challenges of putting an ETAP Real-time system in a nuclear power plant? Most nuclear power plants already have a detailed ETAP design model, so it's not that. The real issue is that our plants were designed and built before the digital age and use mostly analog panel meters and indicators.
By Ms. Mark Bowman, Senior Program Manager of Power System Analysis, TVA

At a given nuclear power plant, nuclear safety is directly dependent on a reliable source of electric power supplied via the plant’s auxiliary power system. The auxiliary power system typically consists of an MV and LV AC and a DC distribution system, powering thousands of individual loads and circuits, i.e., pumps, fans, valves, sensors, and controls specifically designed to protect the integrity of the nuclear reactor and containment structures. This case study explores past practices and recent developments in online monitoring systems using a digital twin. The presentation includes the reasons for online monitoring, the advantages of using a digital twin versus simple data collection, and the multi-faceted benefits of such a system (i.e., business, safety, reliability).

The Tennessee Valley Authority (TVA) is a federally owned electric utility corporation in the United States.  The Tennessee Valley Authority provides low-cost electricity in seven southeastern states and provides flood control, navigation, and land management for the Tennessee River system. With a generating capacity of approximately 35 gigawatts (GW), TVA has the sixth-highest generation capacity among utility companies in the United States and the third-largest nuclear power fleet, comprising seven units at three sites. In addition, they operate four coal-fired power plants, 29 hydroelectric dams, nine simple-cycle natural gas combustion turbine plants, nine combined-cycle gas plants, a pumped-storage hydroelectric plant, a wind energy site, and 14 solar energy sites.

Location: Knoxville, Tennessee, USA

Year: 2022

Real-time monitoring of the auxiliary power system for a nuclear power plant

Challenges

  • Monitor data from the auxiliary power system to understand how it behaves. Focus on Offsite Power circuits and Class 1E systems to accomplish the nuclear plant’s safety-related functions.
  • Adapting old electrical measurement assets to the digital era. Nuclear plants were designed and built before the digital age, mainly using analog panel meters and indicators without digital output and input. Volt meters, Amp meters, Watt meters, and Breaker status lights provide analog data.
  • Finding a solution to connect old nuclear analog plants to the digital world. It is not possible to change equipment. The installation cost of new digital sensors, the cost of redesigning, the cost of outages, and the cost of approval of a new series of digital sensors are very high in the nuclear industry. Minimize the number of new devices while utilizing the existing metering system.
  • Linking object data to the virtual model. Comparing real data from the field with model data will improve the maintenance. Real data should be available during all plant events.
  • To save offline time per event. Every nuclear plant breakdown (16 - 24 hours) costs nearly 1 million dollars.

Which solutions did they choose?

Selected applications

They utilize the ETAP Digital Twin model and the ETAP Real-Time solution. ETAP will deliver all hardware, including servers.

As a company managing nuclear energy production, they have used ETAP for many years. 

Why do they use Etap?

Main Customer Benefits

  • TVA engineers modeled the Watts Bar Nuclear Plant's auxiliary power system using ETAP software. Security, quality, and certainty of solutions were in the first place during the process. TVA closely works with the ETAP engineers.
  • After Project Approval, researchers made the Design Study and Detailed Design using the ETAP RT solution and provided a Class 1E and an Offsite Power system, according to nuclear standards. All symbols, behaviors, and lines were accessible in the large ETAP libraries.
  • In the design, they applied data concentrators for a 6,9 kV switchgear and a 480 V switchgear. It is a method to transfer analog data from medium voltage (32 points) and low voltage levels (88 points) into ETAP real-time servers. They have used Twisted wires, Ethernet, and fibers (or Wi-Fi) to transfer data from sensors via smart meters and circuit monitors to the servers. Communication
  • ETAP engineers will supply and configure the ETAP RT Server Architecture. The managers decided to divide the installation process into several stages, working step by step on such a critical engineering topic.
  • They decided to build a Watts Bar Auxiliary Power System simulator at a local Chattanooga University (UTC) to simulate the entire power system using the ETAP RT system. The OPAL-RT simulator is used with the ETAP/TVA auxiliary power system model, to test the designed system's resiliency.

What do they think about ETAP?

Opinions

The main benefits of using ETAP Real-time for a nuclear plant are state estimation, that is, getting data for the entire plant system just from limited sensors, online monitoring, having real-time data and historical trending event playback, the ability for troubleshooting and event investigation from the data that's stored, and predictive simulation. Or "What if" analysis, additional operational and historical knowledge of this type, would significantly benefit nuclear safety, operability, and operating costs.
By Ms. Mark Bowman, Senior Program Manager of Power System Analysis, TVA

What's interesting about an ETAP RT system like this, and its real strength, is that people say, "Well, Mark, why wouldn't we just hook up smart meters, and why do we need ETAP real-time?" Because we're getting to monitor about 32 points out of the 6.9 KV and about 88 out of the 480 V. But, by going up to the ETAP real-time server and using the state estimation, in other words, using our ETAP model, we can then realize about 15,000 points that are available for playback or real-time viewing out to the network clients.
By Ms. Mark Bowman, Senior Program Manager of Power System Analysis, TVA



Videos

Online Monitoring of Nuclear Power Plant Auxiliary Power Systems using ETAP Real-Time

At a given nuclear power plant, nuclear safety is directly dependent on a reliable source of electric power supplied via the plant’s auxiliary power system.  The auxiliary power system typically consists of an MV and LV AC and a DC distribution system, powering thousands of individual loads and circuits, i.e., pumps, fans, valves, sensors, and controls specifically designed to protect the integrity of the nuclear reactor and containment structures.  This presentation will explore past practices and recent developments in the online monitoring of such systems using a digital twin. The presentation includes the reasons for utilizing online monitoring, the advantages of using a digital twin versus simple data collection, and the multi-faceted benefits realized from such a system (i.e., business, safety, reliability).


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