POWER November 2012 - 32

TOP PLANTS
Oconee Nuclear Station, Seneca,
South Carolina
Owner/operator: Duke Energy
With license extensions for its three units in
hand, Duke Energy's Oconee Nuclear Station
began a digital controls upgrade program in
2006, and in January 2010, AREVA became
the first supplier to receive Nuclear Regulatory
Commission approval for a safety-related
digital instrumentation and controls system.
That set the stage for the first digital control
system in a U.S. nuclear plant.
Courtesy: Duke Energy
By Thomas W. Overton, JD
T
he Oconee Nuclear Station near Seneca,
S.C., first came online with Unit
1 in 1973; Units 2 and 3 began operation
in 1974. With a total capacity over 2,500
MW, the station-now one of the oldest in the
country-has been a key element of the area
grid for almost four decades, having generated
more than 500 million MWh over its lifetime.
Oconee's three units have a common Babcock
& Wilcox pressurized water reactor
design, each with a capacity of 885 MW. In
2000, the station received a license extension
from the U.S. Nuclear Regulatory Commission
(NRC) that permitted operation through
2034. That, Duke recognized, meant significant
replacements and upgrades would be
required to continue operating Oconee in a
reliable, cost-efficient manner well into the
21st century.
32
Like every other nuclear plant built in the
U.S., the station's original protection systems
were analog. However, over Oconee's lifetime,
the original equipment manufacturers
for the control and protection systems began
to discontinue support for their equipment.
One way or another, Duke needed to replace
it. But rather than simply upgrade with newer
analog systems, Duke made the decision to
give Oconee the first digital control system
of any U.S. nuclear plant.
Digital instrumentation and control (I&C)
systems in fossil and renewable plants are
nothing new and are now largely standard
because of the clear benefits they offer over
analog. However, regulatory concerns over
potential safety issues have slowed deployment
of digital controls in nuclear plants,
particularly in safety-related systems.
In 2006, as part of the overall refurbishwww.powermag.com
ment
program, Oconee's staff began their
effort to upgrade many of the plant's analog
I&C systems. The projects were selected
based on their impact on plant operation.
Duke chose AREVA as the vendor for the
new I&C systems based on the success of its
Teleperm XS technology. The AREVA Teleperm
system was designed for use in the new
AREVA EPR plants that are currently under
NRC design review, but it can also be used
for upgrades at existing plants.
One of the projects involved the digital upgrade
of the reactor protection system (RPS)
and engineering safeguards (ES) system. The
digital upgrades to nonsafety systems such as
the integrated control system could be performed
without modifying the plant's existing
operating license, but the safety-related
RPS/ES digital upgrade project required
NRC review and approval. After several years
POWER | November 2012
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POWER November 2012

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