POWER November 2011 - 81

NUCLEAR I&C
Crossing the Digital Divide
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.
By Ken D. Thomas, Idaho National Laboratory
N
uclear utilities continue to upgrade
aging instrumentation and control
(I&C) systems with modern digitalbased
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 widescale
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 widescale
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
November 2011 | POWER
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
www.powermag.com
(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.
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 im81
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