Informed by EPRI Research, Exelon, Wolf Creek, and Callaway Expect Significant Cost Reductions
EPRI’s Digital Engineering Guide consolidates best practices for digital engineering and installing digital control technology at nuclear power plants. It helps further the aims of Delivering the Nuclear Promise, a U.S. industrywide initiative to enhance nuclear power’s efficiency and long-term viability. “This guide could play a central role in driving digital modifications in the nuclear power industry,” said John Connelly, senior engineering manager at Exelon Generation. “When all utilities are able to apply the same playbook, designs will become transportable and lead to significant reductions in implementation costs and improvements in plant performance.”
Nuclear utilities big and small face financial challenges as electric load growth slows, renewable costs decline, and natural gas prices remain low. Plant modernization is a potential countermeasure that could help revive the economic prospects of carbon-free nuclear power.
“For nuclear plants, the most viable path to long-term sustainability is deploying advanced technologies and harvesting the resulting efficiencies,” said John Connelly, senior engineering manager at Exelon Generation, which operates 22 reactors in the United States.
“Modernization can equip nuclear plants with updated technologies and improved processes to deliver greater economic efficiency and reliability,” said EPRI Senior Program Manager Rob Austin. “Our research has not revealed any technological barriers that would prevent nuclear plants from modernizing, and our initial estimates suggest that some U.S. plants could reduce their operations and maintenance costs by 50%.”
In 2013, EPRI created the Digital Design Guide, which consolidated best practices for digital engineering and installing digital control technology. EPRI in November 2018 updated and upgraded the guide, now called the Digital Engineering Guide. It incorporates risk-informed decision making, which enables users to size digital controls and systems in proportion with the level of risk. It also draws on systems engineering in other high-reliability industries, such as petrochemicals and aerospace. The guide helps further the aims of Delivering the Nuclear Promise, a U.S. industrywide initiative to enhance nuclear power’s efficiency and long-term viability.
“This guide could play a central role in driving digital modifications in the nuclear power industry,” said Connelly. “When all utilities are able to apply the same playbook, designs will become transportable and lead to significant reductions in implementation costs and improvements in plant performance.”
Connelly expects that industry adoption of the Digital Engineering Guide could yield significant savings. A collaborative nuclear industry group (called the Design Oversight Working Group) conservatively estimated that a more consistent digital engineering process could reduce engineering costs by 20% to 40%. According to Connelly, a 20% cost reduction translates to an average annual savings of approximately $500,000 per unit.
To coordinate a more directed modernization effort among global nuclear industry stakeholders, EPRI launched the Nuclear Plant Modernization Initiative in 2018. Austin is facilitating the sharing of technology demonstrations and potential standardized methods, tools, and designs to help inform stakeholder decisions on plant capital investments. Utilities are beginning to apply these solutions and see results.
Exelon Generation Implements EPRI Guide, Reduces Component Count and Outage Rates
Since the 1990s, Exelon Generation has been a leader in applying digital control technology for nuclear power in the United States. Exelon Generation has developed and implemented standardized digital solutions for non-safety-related systems, such as feedwater, turbine, and reactor-level controls and generator voltage regulators. Exelon Generation implemented EPRI’s Digital Design Guide and developed an internal procedure to quantify the risks and consequences of every upgrade.
“Our procedure provides the ‘what,’ and EPRI’s guide provides the ‘how,’” said Connelly.
Exelon Generation recently replaced thousands of analog-based controls known as circuit cards with an advanced distributed control system.
“This enabled us to reduce the component count in the targeted systems by 80%, eliminating millions of dollars in future maintenance costs,” said Connelly. “We now have far fewer components that can fail. The modification also eliminated every single-point vulnerability in the targeted systems and enables plants to run more efficiently.”
In a fleetwide analysis of more than 500 unit-years of operations, Exelon Generation found that applying advanced digital technologies for turbine and feedwater controls reduced forced outage rates by as much as 95%.
Wolf Creek and Callaway Tailor EPRI Quick Guides to Demonstrate Cost Reductions
Plant operators at Wolf Creek (in Kansas) and Callaway (in Missouri) evaluated EPRI’s series of Quick Guides for implementing continuous online monitoring for specific components. The guides equip operators to evaluate every degradation mechanism affecting a component, then recommend a combination of sensors, monitoring, and analytical methods to address the degradation.
“For us, a successful sensor-based equipment monitoring program can move a plant from time-based to condition-based maintenance with reduced costs,” said Wolf Creek’s manager of strategic projects, Matt Hall, who collaborates with Lorne Poindexter of Callaway on this initiative. “EPRI’s guides are an excellent starting point, but because they are comprehensive, we found that implementing them in their entirety could be cost prohibitive in some cases. We revised the Quick Guide methodology and used that to demonstrate that condition-based maintenance can be implemented at a reasonable cost and with acceptable risk, while yielding a positive return on investment for those projects undertaken.”
The full suite of component sensors recommended by a Quick Guide can help enable earlier detection of degradation. Working with EPRI, Wolf Creek and Callaway found that for them an optimal subset of sensors may allow some anomalies to progress—but to a stage that can be detected far in advance of component failure.
With support from EPRI, Callaway and Wolf Creek evaluated work order data for the condensate system and found that condition-based maintenance can reduce the plants’ annual pump maintenance costs by $15,000 and annual motor maintenance costs by $35,000.
“For the condensate system, we found that the combination of vibration sensors and motor current signature analysis gives us the biggest bang for the buck,” said Hall. “They provide a solid return on investment for the chosen projects when accounting for implementation and operational costs as well as the 10-plus-year lifetime of the monitoring equipment. Because of economies of scale, we could expand this infrastructure to additional systems and components at a much lower price point.”
Callaway and Wolf Creek are working with EPRI to implement other parts of the revised Quick Guide methodology for several secondary systems. EPRI plans to incorporate the revised methodology into future guidance.
“These utility implementations show how plant modernization involves not just the core equipment controlling a nuclear site, but also how personnel monitor and maintain that equipment,” said Austin. “It will take this level of change across the entire plant to fully realize the benefits of modernization. That is the integrated approach of process improvement and technology we want to bring to the utilities.”
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