Nuclear Industry Prepares for Safety-Related Digital Upgrades

• Industry readying for digital upgrades of safety-related instrumentation and control systems
• Utilities hosting 11 workshops on how to prepare required documentation
• NRC headquarters senior staff and regional inspectors will participate

One of the hallmarks of the U.S. nuclear industry is its dedication to continuous improvement and the long-term operational viability of the reactor fleet. The industry is now taking its next leap forward in modernizing the fleet with digital upgrades to safety-related plant systems.

Over the past 20 years, nuclear power plant licensees have largely completed digital modifications to non-safety related systems in operating U.S. reactors. These systems include turbine control, feedwater control and other secondary support systems.

Now, with the recent issuance of guidance from the Nuclear Regulatory Commission, the industry is preparing for digital upgrades to the safety-related instrumentation and control (I&C) systems such as:

• Replacing analog controls for safety-related support systems such as chiller systems (heating, ventilation, and air conditioning)
• Replacing safety-related analog relays (including timing relays) with digital relays
• Replacing analog controls for emergency diesel generator supporting systems and auxiliary systems such as voltage regulation
• Installing safety-related circuit breakers that contain embedded digital devices
• Replacing safety-related analog recorders and indicators.

With nearly all U.S. nuclear utilities having extended their reactors’ operating licenses to 60 years and some beginning to seek second extensions to 80 years of operation, the need to upgrade these systems and further modernize the operating fleet is vital.

To achieve this important change, NEI in 2015 formed a working group of industry experts and NRC staff to resolve key technical and regulatory issues and facilitate the implementation of I&C upgrades. After more than three years of effort and more than 50 public meetings, the NRC and industry worked to produce guidance on how to make these upgrades.

The May 31 regulatory issue summary document (RIS) outlines how reactor owners can use “qualitative assessments” to show that proposed safety-related and non-safety related digital I&C modifications will have a sufficiently low likelihood of failure, including common cause failures, due to software or other issues.

NEI and the industry are now moving forward with a series of 11 informational and training workshops to ensure that industry members and NRC regional staff know how to use the RIS to prepare and document assessments for digital modifications and upgrades at reactor sites.

The training will provide examples of what kinds of digital modifications and upgrades the RIS should be applied to, and encourage the immediate use and implementation of the RIS in initiating digital I&C projects across the operating reactor fleet, NEI Senior Project Manager for Life Extension and New Technology Jerud Hanson says.

The workshops are designed for professionals at nuclear reactor sites and utilities responsible for developing digital I&C design modifications and the associated plant design change reviews under 10 CFR Part 50.59.

The training program will be being hosted and conducted by various NEI member utilities across all four NRC inspection regions, with the support and participation of NRC regional inspectors and NRC headquarters senior management staff.

Additional workshops may be scheduled as necessary. Workshop registration can be found here. Registration assistance is available by emailing [email protected].

For all other matters related to the RIS or digital I&C, contact Jerud Hanson at [email protected].