One of the great successes of the power generation industry over the past two decades has been the significant increase in nuclear plant reliability and other performance standards. However, there is reason to be concerned that the design, operation, and maintenance practices used by the current fleet of plants do not leverage all the possible advantages from a digital controls upgrade. Perhaps past success is the biggest barrier to future success.
Nuclear utilities continue to upgrade aging instrumentation and control (I&C) systems with modern digital-based systems to address reliability and obsolescence concerns. In addition, the industry has demonstrated that these systems can be successfully developed and deployed even for highly safety-significant applications, such as reactor protection.
However, three factors have retarded wide-scale implementation of digital technology for plant modernization and business innovation:
- Large-scale digital upgrades entail considerable risk.
- The upgrades are very costly and have not led to bottom-line business improvement, financial or otherwise.
- Cybersecurity concerns discourage wide-scale digital integration.
A new national research program is now under way in the U.S. to address these concerns and finally break through these barriers to achieve a true digital transformation of operating nuclear plants.
Missed Opportunity
The industry approach to digital upgrades has always been one-for-one replacements, that is, new systems replaced the earlier control system functions. Consequently, such replacements fail to completely leverage the increased capabilities of new digital replacements. The common theme of these upgrade projects has been to minimize cost and risk by avoiding large changes to the plant operating infrastructure, including plant operating procedures, training, operator familiarity, design basis, and licensing basis of the controls system. Often, digital upgrades were designed to be completely transparent to the operators, some going so far as to retain the board devices from the previous analog systems.
By forcing digital systems into the footprints of their analog predecessors, the inherent capabilities of digital designs to improve business performance are lost. Beyond plant control and protection functions, digital systems can also facilitate communications, support automated work processes, enforce human performance expectations, detect and correct errors, provide enhanced understanding through visualization techniques, and provide many other useful capabilities. By fully exploiting digital technology, it is possible to lower the cost of conducting plant operational and support activities while improving quality, efficiency, and nuclear safety.
The approach the nuclear power industry has taken with digital technology stands in contrast to that of other industries. We have seen digital technology literally redefine industry operating models by automating and greatly improving even routine tasks such as package delivery. We have also seen it successfully implemented in safety-critical applications—from flight deck avionics to advanced medical procedures—where it not only replaces the control functions but also substantially transforms how the operational activities are performed, making them much more efficient and accurate.
Consequently, the digital migration in the nuclear power industry has been somewhat disappointing. It has not led to bottom-line business improvement; instead, a good case can be made that digital control upgrades actually increase operating costs. We are simply not getting the performance dividend out of digital implementation that other industries are enjoying. To fully understand why this is such a lost opportunity, the larger context of industry’s performance needs to be considered.
Standardizing Can Be Limiting
The U.S. nuclear power industry has enjoyed impressive performance improvement over the past 15 years. It was in the mid-1990s when the industry accelerated the standardizing of plant processes and conduct of operations. This emphasis on standardization was made through the concerted efforts of utilities and the Institute of Nuclear Power Operations (INPO) to set challenging performance targets and to undergird these efforts with standards of excellence, comprehensive process templates, and human performance expectations.
Performance improvement became evident in virtually every aspect of plant operations and support, particularly improving key performance indicators such as capacity factor, scram rate, forced loss rate, dose, refueling outage length, and overall cost performance. The performance targets were met. This achievement was even more remarkable because the goals for operational excellence included both profitability and nuclear safety.
However, sustaining this rate of performance improvement has proven to be difficult. Within the past five years or so, the industry has experienced a reduction in the rate of performance improvement such that today, several of the important measures have shown virtually no year-to-year improvement.
This flattening of the performance curves was not unexpected. Every operating model is subject to the classic “S” curve in the relationship between effort and performance, as illustrated in Figure 1. In the early years of the current operating model, roughly the mid-1990s to the mid-2000s, the industry was below the knee of the curve and enjoyed highly leveraged performance improvement relative to effort. As the operating model matured, much of the low-hanging fruit was picked, and it became increasingly difficult to maintain the rate of improvement experienced in earlier years, particularly with fleet capacity factors, scram rates, and forced outage rates. The operating point had moved out to the flat part of the performance curve, the region of diminishing returns.
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| 1. Old model. This performance curve is based on the current operating model. Source: Ken D. Thomas |
A survey of the staff at nuclear utilities would surely find general agreement that the industry continues to increase its performance expectations at the same time as the industry is making plant processes more complex. In addition, further reductions in consequential human error are proving difficult to achieve because improvements rely mainly on correct worker behaviors and barriers to prevent events—both difficult to manage. Technology is greatly underutilized in the quest to reduce human error, as has become the norm in other safety-critical industries.
Again, these factors confirm that the industry’s operating model has largely exhausted its potential for substantial performance improvement in future years.
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