Written by Bruce Greer, Principal Technical Leader - Initial Operations and Maintenance
Operations and maintenance (O&M) account for 66% of operating costs for today’s nuclear plants, with fuel supplying the other 34%. This separates nuclear from fossil fuel plants, where O&M costs are significantly lower than fuel costs.
In an increasingly efficient electricity generating market, optimizing O&M for nuclear plants is one of the most important routes to reducing overall costs and maintaining economic competitiveness. Beyond the current nuclear fleet, O&M costs must also be reduced for advanced reactors (ARs) to succeed in the future, including small modular reactors (SMRs), non-light water cooled reactors, and microreactors.
O&M costs include the costs of inspections, repairs and replacements, chemistry control, radiation protection, staff and training, security, and regulatory compliance, to name just a few. New technologies are constantly being developed both in and outside the nuclear industry that can be applied to lower these costs for conventional and advanced nuclear plants.
EPRI focuses on three main research areas to help nuclear plants operate more safely, efficiently, and competitively: automation, diagnostics, and guidance on best practices.
How automation can lower nuclear O&M costs
Remote, automated new technologies such as drones, robotics, and computer programs can be used to make plant O&M more efficient.
EPRI is working to develop and demonstrate these technologies in the nuclear industry, some of which have been used in other industries but not yet applied in nuclear plants.
For a high-level overview of different automation technologies that could be applied in the nuclear industry, visit 3002025693. We also provide a research roadmap and prioritization to deploy the highest-leverage technologies, which could reduce staffing needs by 25% and reduce several other major expenses, in 3002023869.
Digital Twins
A digital twin is essentially a computerized replica model of a reactor. The digital twin can be fed data from the reactor’s instruments and updated in real-time to gain insights on maintenance needs and operational performance.
EPRI is examining how digital twins can be used to improve operational efficiency. ARs are particularly well positioned to benefit from digital twins because most of these reactors are still in the design stage, and the digital model can be integrated from the outset over the plant’s entire lifecycle.
We take a closer look at digital twin applications for advanced reactors in 3002023904.
Robotics
Beyond cost reductions, robotics and drones could be used to provide several O&M advantages, including:
- Decreased calendar time and labor hours to complete certain tasks,
- Decreased exposure of personnel to a variety of industrial and radiological hazards,
- Measurements, information, and work while equipment is online (rather than requiring an outage or downpower),
- Increased quality of data collected from an inspection,
- Increased scheduling flexibility among personnel (for example, by reducing the need to coordinate between maintenance and health physics when the robot is used in an elevated radiation area instead of a human), and
- Decreased administrative burden to perform certain maintenance activities that require significant oversight when performed manually.
To learn more about near-term opportunities for increasing O&M efficiency using robotic process automation, visit 3002023899.
Chemistry
Controlling reactor coolant chemistry is a significant cost driver for nuclear plant operations. During operation, corrosive ions can build up that can cause damage to fuel elements and other components.
Today’s water-moderated nuclear reactors carefully control water chemistry using chemical additions and devices such as ion exchangers. This helps reduce corrosion and leakage risks from fuel rods, and it also protects the components of the steam cycle and pressure vessel.
EPRI spearheaded our SMART chemistry program to provide analyses of different chemistry automation technologies, such as for steam generators (3002015805) and reducing maintenance times for ion chromatographs (3002014377).
Reactor chemistry sampling and measurements are typically performed manually by personnel. Automating sampling for the existing fleet could require retrofitting with costly equipment and may not be economically advantageous; however, other intangible benefits such as improved data quality and consistency could make up for the difference. We examine the business case for automating plant chemistry measurements in 3002020440.
Looking beyond O&M economics, chemistry automation can also increase the consistency of reactor chemistry, data availability, and be used to automate other processes, such as chemical additions. This is particularly useful in load-following and flexible-operation plants, since these have more frequent changes to chemistry that need to be adjusted for.
For ARs, current chemistry automation technologies will be most applicable to light-water moderated designs such as SMRs. We provide an assessment of automation technologies to reduce chemistry and radiochemistry costs for light-water reactors in 3002010493.
Non-light water moderated ARs will have significantly different chemistry profiles, each with their own unique set of challenges that will need to be addressed. We have planned research focused on performing a gap analysis and developing a roadmap for a chemistry control framework for non-aqueous coolant chemistry.
How diagnostic technologies can lower nuclear O&M costs
Reactors use various sensors to monitor and control different aspects of operation to ensure safety, efficiency, and performance. These include temperature sensors, pressure sensors, level sensors, radiation detectors, flow sensors, neutron flux sensors, position sensors, chemical sensors, vibration sensors, pressure relief valve sensors, and environmental sensors.
Sensors work together to provide real-time data to reactor operators and control systems, enabling them to make informed decisions and maintain safe and efficient reactor operation. Additionally, they are crucial for ensuring that the reactor remains within its design parameters and responds appropriately to any anomalies or emergencies.
AR designs often use higher temperatures, radiation fields, neutron energies, more corrosive environments, and/or pressures than existing reactors, to name just a few differences, and will require new sensors that can withstand harsher environments. Further, developing advanced sensor technologies can help the existing nuclear fleet by improving data quality and O&M efficiencies and provide new opportunities for remote monitoring and inspection.
EPRI is working to ensure that the sensors required for operation in high-temperature and high-radiation environments are ready at the time they’re needed for advanced reactors.
For our outlook on the state of sensor technologies for advanced reactors and a roadmap for the remaining research required, visit 3002026618.
Nondestructive evaluation
Nondestructive evaluation (NDE) refers to a set of techniques and methods used to inspect, test, and evaluate the integrity and safety of components, systems, and infrastructure without causing damage or compromising their functionality. NDE is a crucial aspect of maintaining the safety and reliability of nuclear power plants and facilities by detecting any flaws, defects, or degradation in materials and structures, ensuring that they meet safety standards and regulatory requirements.
NDE methods can allow for inspections of components while the nuclear reactor is in operation or during planned outages, minimizing downtime and ensuring that any necessary maintenance or repairs can be conducted promptly, improving O&M efficiency.
Ultrasonic testing, one NDE method, uses high-frequency sound waves to detect defects or discontinuities within materials. It is of particular interest for reducing O&M costs with in-service inspection. However, ultrasonic testing in ARs will require development of sensors resistant to higher temperatures. We analyze the technology status and remaining gaps in 3002021015.
Regulations have gotten more stringent over time, making effective and reliable NDE techniques even more imperative. EPRI identifies challenges from past NDE methods and remaining needs to support future reactors in 3002010494.
Embedded sensors
When setting concrete for a new nuclear reactor, proactively embedding sensors can make it easier to test inaccessible areas and ensure long-term safety.
EPRI is examining different embedded sensor technologies and diagnostic methods that can provide data and help plants inspect inaccessible areas, improving their safety and case for license renewal.
For an overview of concrete-embedded sensors, visit 1023006.
Embedded scintillators, for example, could use x-rays to inspect and detect defects in reinforced steel-concrete-steel structures. We examine different applications of x-ray technology for inspections in 3002022905.
For more information on advanced diagnostic and quality-analysis methods, consult 3002023902.
How EPRI’s guidance can lower nuclear O&M costs for the future fleet
EPRI creates best-practice guides and technology roadmaps for light water reactors and advanced light water reactors, and we are now updating our guidance to reflect the latest experience, technologies, and lessons learned to meet O&M needs for the future fleet of ARs.
Risk-informed inspections
Risk-informed inspections refer to inspections and assessments that prioritize resources and efforts based on the risk levels associated with different components and systems. Risk-informed inspections help nuclear plants optimize resource allocation for inspection and maintenance practices while enhancing safety.
Effective risk-informed inspections require accurate risk analyses. Past EPRI research revealed that plant inspections often overfocused on low-risk components; instead, we provide updated guidelines for risk assessments of light-water moderated reactor components in 3002003119.
EPRI also evaluates risk analysis methods and tools available to ARs, specifically, to outline the highest research priorities that will support efficient risk-informed inspections for the future fleet. Our findings are available in 3002026495.
In-service inspections
Outages tend to be highly costly in the nuclear industry. Accurate risk assessments improve capabilities for in-service inspections, which allow the plant to stay online longer before a planned maintenance outage.
EPRI developed and demonstrated a risk-informed in-service inspection methodology that can reduce outage time and significant costs for both new and existing nuclear reactors. The in-service inspection methodology, available in 3002010481, is based on deterministic analyses of design stress reports, and it could be made even more efficient with the integration of digital twins and advanced sensors for ARs.
Construction
In addition to analyzing construction sensor technologies, EPRI provides guidelines for assuring construction quality in structures such as concrete. We first published guidelines for concrete placement quality in 2013 with a field-deployable guide, available in 3002000520.
This guide was updated in 2019 to include inspections for reinforced and self-consolidating concrete, which are gaining interest in the nuclear industry and could be especially useful for ARs. The guide was also updated to account for changes in standards and codes.
Our most up-to-date guidance for performing inspections of reinforced and self-consolidating concrete construction is available in 3002015934.
Digital instrumentation and control
Instrumentation and control (I&C) systems are increasingly relying on digital technology, and control rooms at nuclear plants now use more digital interfaces than ever before. While these technologies come with countless benefits and efficiencies, they also need to be carefully tested to eliminate risks.
EPRI provides a high-level guide to engineering effective digital I&C interfaces and their O&M advantages in 3002011816.
I&C replacement and design
Replacing I&C systems can contribute significant O&M costs to nuclear plants, so it is important for owner-operators to create an integrated lifecycle management plan that accounts for obsolescence. We provide guidance on how to create such a plan in 3002002852.
After operation begins, owner-operators are responsible for maintaining their design and licensing basis. This makes it difficult to update I&C systems even when new, more efficient technologies become available. EPRI provides a comprehensive guide to designing and modifying control room and digital I&C systems in 3002004310.
EPRI is also focused on designing digital I&C systems with lower risks. We define risk sensitivities for different components and outcomes, and how to work towards minimizing these risks, in 3002016698.
Testing in other industries has helped demonstrate methods for reducing risks in digital I&C and software. We examine how combinatorial testing can be applied for nuclear digital I&C systems in 1023010.
Human factors
Digital I&C systems create new human-based risks, which also need to be accounted and engineered for.
EPRI created three training courses to help train staff for using more digital I&C in modern control rooms. Our goal with these courses is to reduce staff training O&M costs while also improving personnel efficiency and operational safety. The courses are available in 1024860.
New technologies could be used for greater staff optimization to increase safety and efficiency while lowering O&M costs. EPRI identifies 25 technologies that can help optimize SMR plant staff in 3002007071.
Plant security
The nuclear industry maintains high safety standards, which requires different forms of security and associated O&M costs.
EPRI provides security technology analyses for new nuclear plants in 1015112 to help owner-operators allocate their security budget effectively and meet NRC standards. We also assess new and potential security technologies for use in the nuclear industry in 3002018240.
Cyber security
Nuclear plants using increasingly digital I&C systems will need greater cyber security defenses to eliminate risks.
EPRI provides a program guide to help nuclear power facilities define, implement, and monitor a cyber security plan in 3002012754.
We provide guidance on available technologies for identifying and addressing cyber security risks in 3002012752.
Today, before a new nuclear plant can startup for the first time, it needs to demonstrate cyber security. We provide guidance on implementing and demonstrating adequate cyber security systems during plant construction in 3002010470.
Chemistry control guides
To support the existing fleet, EPRI developed comprehensive chemistry control guides for advanced boiling water reactors (3002008028) and advanced pressurized water reactors (3002008295).
EPRI also provides guidelines for developing plant online monitoring systems in 1022988. Continuous monitoring can generate a more accurate understanding of conditions and can reduce the need for maintenance outages while increasing O&M efficiency for instrument calibrations, quality control, and health physics.
O&M support for the current and future reactor fleet
Investigating and demonstrating technologies that can improve O&M efficiency has long been a core focus of EPRI. Our resources are designed to provide owner-operators with the most up-to-date information and technology assessments to help them succeed. These O&M resources are useful tools to help nuclear plants operate more safely, efficiently, and economically.
Full access to EPRI’s research and guides for designing and implementing efficient plant O&M is available for free to EPRI members. You can get in touch with us at ant@epri.com.