Challenges and Opportunities for Nuclear Digital Twins

digital twin conceptual imageA rapidly evolving area of practice in the digital representation of the workings of an operating nuclear reactor is the use of “digital twins” technologies.

Researchers at Idaho National Laboratory (INL) are taking embedded smart sensors and systems one step further with the development of so-called “digital twins.” The resulting software applications are essentially virtual replicas of nuclear reactors.

In recent years, digital twin (DT) technologies have been applied in the nuclear industry both in the current light-water reactor fleet and for design of advanced reactors. The state-of-the-art survey report published in December 2021 provides an extensive account of the DT application in the nuclear industry.

These efforts include collaborative efforts across advanced reactor designers, nuclear utilities, DT vendors, university researchers, and national laboratories and are focused on a variety of applications throughout a plant’s lifecycle, such as design, licensing, regulatory compliance, emergency response, modification, engineering analysis, construction, operation and maintenance (O&M) efficiency, and testing.

A key application area for a plant operator using a digital twin is predictive maintenance. A digital twin relies on intelligent modules that continuously monitor the condition of individual components and, in aggregate, whole systems.

nrc logoA second application for the U.S. Nuclear Regulatory Commission (NRC) is in oversight and compliance monitoring of the operations of a nuclear plant. The NRC is interested in determining how digital twins can support its regulatory role.

A third application is in the design of a new reactor, especially an advanced design, which allows the engineers working on it to try out different approaches to optimize performance and safety.

The Role of Virtual Representation

World Nuclear News reported in March 2021 that digital twins connect virtual representation with plant infrastructure. Catherine Cornand, senior executive vice president of the Installed Base Business Unit at Framatome, told the news service,

“Digital twins also provide a bridge between the digital representation, or model, and physical plant data. By connecting digital twins with their associated fault libraries, abnormal behavior in a plant system can be detected so that any problems can be identified and addressed early. This technology will also be critical as reactor developers design the next generation of technologies, with the goal of reducing operation and maintenance costs so they are closer to that of a combined cycle natural gas plant, which are around seven times lower than a legacy nuclear power plant.”

schema of digital twin applications

Conceptual Representation of a Digital Twin for a Nuclear Reactor.  Image: Framatome

In October 2020 the U.S. Department of Energy’s ARAP-E program awarded Framatome funds to conduct a study of “Digital Twin-Based Asset Performance and Reliability Diagnosis for the HTGR Reactor.” The goal of the project is to reduce O&M costs.

NRC’s Future Focused Research

In order to explore the near-and-long-term opportunities for using digital twins, the NRC and the INL have collaborated on an NRC sponsored and funded ‘future-focused’ research project. The agency laid out three objective for this work.

  • Understand the current state o f the technology and potential applications for the nuclear industry.
  • Identify and evaluate technical issues that could benefit from regulatory guidance.
  • Develop infrastructure to support regulatory decisions associated with digital twins.

INL Team Members Discuss Their Work

This blog interviewed Vaibhav Yadav, PhD, the principal investigator at the INL who worked on the first phase of the project with Christopher Ritter, Director of the INL’s Digital Center for Excellence, and other members of the research team.

The lab recently published a report on the first phase of the project which found that a digital twin will allow reactor operators an unprecedented level of monitoring, control, supervision and security.  Full Citation in NRC ADAMS ML21361A261

V. Yadav, V. Agarwal, A.V. Gribok, R.D. Hays, A.J. Pluth, C.S. Ritter, H. Zhang, P.K. Jain, P. Ramuhalli, D. Eskins, J. Carlson, R.L. Gascot, C. Ulmer, R. Iyengar. Technical Challenges and Gaps in Digital Twin Enabling Technologies for Nuclear Reactor Applications. Letter Report TLR/RES-DE-REB-2021-17, INL/EXT-21-65316, December 2021.

“We started with the NRC’s vision of the need to understand the state of the art of digital twins. This is future focused research,” says Vaibhav Yadav.

The NRC’s view is that nuclear plant operators might use digital twins as part of their application for a license for a new plant or to request a change to the current license.

Yadav noted that digital twins, in addition to giving plant workers new insights into the way their reactors are working, also hold the potential to operate them more efficiently which could yield cost savings.

In terms of using digital twins in the design of new reactors, Chris Ritter said that the design and  licensing of the Versatile Test Reactor (VTR) will rely on digital twins. He added that digital twins have potential applications across a broad range of reactor development efforts now and in the future.

vtr-and-ardp_thumb.png

However, Ritter says the greatest potential in the near term is for operating reactors.

“To get the most value out of development of a digital twin, the target application is going to be for an operating asset.”

He quickly added that there is an evolving area of developing applications in the design space, “in other words, where a physical asset may not exist.”

Instead of designing each physical reactor component first, and then adding instrumentation and control to that component, the digital and physical components are designed together in a way that the engineers can try out alternative approaches to the design of the combined systems of sensors and the components who’s condition are being monitors by these sensors.

nuclear sensors

Making sense of all the data that comes from the sensors is a key challenge that is similar to the one encountered with condition monitoring products used in manufacturing plants.

This area has a lot of potential because, according to Ritter and Yadav, virtual environments will, for example, allow developers to explore gaps in sensor coverage for a new reactor.

Sensor networks in a digital twin could also support nuclear nonproliferation efforts by tracking the current status of components and systems and automatically tagging any unplanned changes. For instance, it could detect unauthorized diversion of spent fuel from a reactor for the nefarious purpose of reprocessing it to harvest PU-239 from it.

What’s Next for Work on Digital Twins at the NRC and INL?

The NRC is continuing to sponsor the work at the INL with the same three objectives in mind that guided work on the first report.

• Understand the current state of the digital twin technology and potential applications
• Identify and evaluate technical issues that could benefit from regulatory guidance
• Develop infrastructure to support regulatory decisions associated with DTs.

Some of the potential application areas of applying DTs in the nuclear industry are design and licensing, plant construction, training simulators, predictive operations and maintenance, autonomous operation and control, failure and degradation prediction, obtaining insights from historical plant data, and safety and reliability analyses.

Current efforts in the nuclear industry are focused on specific enabling technologies needed to implement DTs, such as advanced sensors, digital computing and communication infrastructure. Future research on potential applications of DTs may include machine learning and artificial intelligence.

Key Challenges of Digital Twins

The joint INL/NRC team, which also include technical input from scientists at Oak Ridge National Laboratory, sees the scope of current and future work falling into a short list of categories.  This list may grow as new findings are documented by the team.

  • Use of new types of sensors or multimodal sensors
  • Installation of a greater number of sensors and more varied sensors
  • Continuous, real-time collection of sensor data
  • Evaluation of uncertainty for new sensors
  • Integration of legacy sensors
  • Uncertainty quantification and propagation in model development and integration
  • Verification and validation of integrated, heterogeneous models

The research team has been invited to speak about its work at the NRC’s Regulatory Information Conference to be held in Washington, DC, March 8-10. A second report with additional findings is expected to be published as a result of the NRC and INL collaborative effort later this year.

The research team at the NRC and the INL wrote in their report that additional effort is needed from interested stakeholders to meet the challenges and bridge the gaps in implementing DT-enabling technologies in nuclear reactors.

“Due to stakeholder interest and industry trends, the NRC is continuing to explore the regulatory viability of digital twins for nuclear power plants by pursuing additional research in the application of advanced sensors for monitoring system performance, integration of security and safeguards within digital twins, and regulatory considerations for use of DTs. “

The research team emphasized that these activities aim to increase knowledge, enhance communication, and build mutual understanding of DT applications in nuclear power plants.

“Digital twins (DTs) in complex industrial and engineering applications have proven benefits that include increased operational efficiencies, enhanced safety and reliability, reduced errors, faster information sharing, and better predictions. The interest in DT technologies continues to grow, and the technology is expected to experience rapid and wide industry adoption in the next decade.

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This blog post was written and published by Neutron Bytes.
For additional information on the INL and NRC work on digital twins contact:

Laura Scheele, Versatile Test Reactor Communications Director   |  Idaho National Laboratory
laura.scheele@inl.gov   |   Phone: 208-526-0442   |   Cell: 219-381-8672    Idaho Falls, ID   |

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