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Fully Digital Nuclear I&C Upgrade Gets ‘Unprecedented’ NRC License

A fully digital nuclear reactor instrumentation and control system (I&C)—the first of its kind in the U.S.—at a Purdue University research reactor in West Lafayette, Indiana, has been licensed by the Nuclear Regulatory Commission (NRC). 

Upgrades to digitalize Purdue University Reactor Number 1 (PUR 1)—a pool-type12-kWt reactor (that runs at 1 kW) originally built in 1962—began in 2012 under a grant from the Department of Energy (DOE). The university submitted a license amendment request to upgrade the I&C system in February 2017. 

The NRC granted the unprecedented license on April 1, 2019, allowing the university to upgrade the systems. In doing so, it accepted—for the first time—parts certified under the German Nuclear Safety Standards Commission (KTA), rather than under domestic standards. The regulatory body said it accepted the parts through the agency’s initiative for a risk-informed and performance-based regulatory process. 

The upgrades, which appear to have been completed, pave “the way for widespread implementation of digital technology in both research and industry reactors,” the university said on July 8. 

“The fact that the NRC is accepting a digital console for a small research reactor, with parts certified under the KTA standards, signals the regulatory body moving toward approval in a large industry reactor,” said Clive Townsend, the supervisor for Purdue’s reactor.

According to the NRC, the I&C systems at nuclear plants function as plant “nervous systems,” and they serve the critical function of providing control and safety information on plant operation. “Digital technologies can be used to combine safety functions together for improved control and increased operational efficiency,” it acknowledges.

“Digital systems can also improve the self-diagnostics of automatic plant protection systems. Finally, the increased use of digital technology is expected to improve safety. These benefits have been demonstrated in domestic and foreign nuclear facilities, as well as other non-nuclear process industries (e.g. petrochemical).” The NRC also noted that new reactor designs have “highly integrated digital systems, and the existing fleet of operating reactors are implementing digital upgrades to address obsolescence issues with analog equipment.” 

However, the NRC says that through licensing activities and inspection oversight, the commission is adamant that licensees employ robust digital designs commensurate with risk significance, and that licensees use high-quality software development practices. “Part of the NRC regulatory focus includes the prevention and mitigation of inadvertent digital failures and maintaining an appropriate level of diversity and defense-in-depth within the plant,” it says. 

The fully digitized I&C system at PUR-1 was developed as a collaborative effort between Purdue, California-based measurement technology company Mirion Technologies and Curtiss-Wright Corp., a North Carolina–based engineering firm. 

Video from the Purdue School of Nuclear Engineering

It includes a neutron flux monitoring system and detectors in the fission chamber, compensated ionization chamber, and two uncompensated ionization chambers. The upgrade also included installation of associated cabling, safety channels, equipment racks, and the control console

According to the university, the new system provides high-temporal resolution data points for all facility data, enabling researchers to view tests and retrieve live data from any remote location around the globe. That data could allow researchers to identify performance interruptions, which may occur before the scheduled maintenance time, making them safer and extending their lifetime. 

It also helps the School of Nuclear Engineering to move away from aging components, such as vacuum tubes and hand-soldered wires from the 1960s, and embrace modern technology, such as LEDs, ethernet cables, and advanced electronics. “If parts needed to be replaced, digital ones are far less expensive and more commercially available than analog parts,” the university said. 

Sonal Patel is a POWER senior associate editor (@sonalcpatel, @POWERmagazine)

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