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Part 4 of 4 Parts (Please read Part 1, Part 2 and Part 3 first)
     Dan Stoddard is the Senior Vice President and Chief Nuclear Officer of Dominion Energy. He presented historical data at the May NRC briefing that documented "tangible performance improvements" in nuclear plants where the controls for their feedwater pumps and steam turbines were upgraded from analog to digital control. Conventional pressurized water reactors which have accomplished the digital steam turbine upgrades have one seventh of the unplanned outages or “scrams” of plants still using analog controls.
     Stoddard said, “From an engineering standpoint, the ability [to] do self-diagnostics, plant monitoring, get information from the [digital] system to allow improvements in engineering and improvements in plant reliability is substantial.”
      In spite of the benefits of digital upgrades, the operators of some nuclear power plants say that is has been hard to justify these upgrades because of the upfront costs and the time and effort that have to be expended to work through the regulatory process at the NRC to get approval for the changes.
     About a decade ago, Duke Energy switched the monitors for water temperature and pressure in the reactor as well as the status of the reactor coolant from analog to digital for their Oconee Nuclear Station in South Carolina. These are some of the most important safety monitoring systems and the three Oconee reactors were the first in the U.S. to make those changes. These changes allowed the Oconee reactors to track temperature and pressure in real time so that the reactors can run more efficiently and problems can be dealt with automatically. However, these upgrades were very expensive and time consuming. Stephen Vaughn is the NEI Senior Project Manager. He said, with respect to the upgrades, “They eventually got done, but it was a burden. It took a long time.” These upgrades allowed the Oconee plant to generate more electricity, but no further digital conversions projects are being planned at Duke Energy at this time.
     It is probable that as the U.S. nuclear industry gains experience with adding digital controls to nuclear power plants, the benefits will grow. This would make it easier to sell the cost, time and effort for upgrading to the owners of the nuclear power plants. The NRC allowed the Purdue reactor upgrade to utilize a digital console which incorporates parts that have international standards certification. If domestic standards certification had been required as is usually the case for NRC permission, the cost would have been much higher.
     Townsend said, “The fact that the NRC is accepting a digital console for a small research reactor, with parts certified under the [international] standards, signals the regulatory body moving toward approval in a large industry reactor.”
     NEI officials have pointed out that the Purdue research reactor is very small when compared to a conventional nuclear power reactor. They say that any results from the Purdue project might not be applicable to the U.S. commercial nuclear power industry in general. Vaughn did say that “from a digital technology perspective, there are some lessons we can learn from it.” It may take years before the Purdue team has conclusions about how reactors can leverage the full benefits of digital instrumentation and control while remaining safe from cyberattacks. He said, “We are just getting started.”