Making Safe Nuclear Plants Even Safer at Southern Nuclear

Danny Bost

The following is a guest blog post by Danny Bost, Executive Vice President and Chief Nuclear Officer for Southern Nuclear.

If you’re reading this blog, it’s pretty safe to say that you’re a proponent of safe, clean, reliable and affordable energy. As the Chief Nuclear Officer for Southern Nuclear, it’s my job to ensure that our six operating units deliver exactly that to our customers across the Southeast.

I think we do that pretty well, but as a learning culture, we’re always looking for performance improvements. That’s why we are excited about the opportunity for Plant Vogtle to pilot the application of NRC Rule 10CFR50.69 “Risk-informed Categorization and Treatment of Structures, Systems and Components (SSCs) in Nuclear Power Plants,” a voluntary rule published in 2004.

Since probabilistic risk assessments were first undertaken in the 1980s, plants have continued to use those studies to identify key potential safety improvements. As these improvements have been made and the results of the studies used to inform plant operations, the safety and reliability of the fleet has improved substantially.

A lot of the previous information is known to many. I will add to the conversation by sharing what Southern Nuclear has learned in incorporating risk insights, specifically in implementing 50.69.

Southern Nuclear’s adoption of 50.69 is the most far-reaching risk-informed application approved to date. Recategorization has allowed us to apply alternate treatments and targeted testing (versus one-size-fits-all requirements) to improve safety and reduce the burden of SSCs that have low risk-significance.

For example, using the 10CFR50.69 rule, the Vogtle containment spray pumps, which are safety-related, have been assessed to be low safety significant. Applying the EPRI-developed guidance, the pumps’ full-flow test frequency was changed from 18 to 54 months and the tests were removed from the scope of Vogtle’s V1R19 outage, which is underway right now. The tests were replaced with an alternative that is estimated to save $200,000 per outage per unit and will improve safety by simplifying the outage schedule and infrastructure development—specifically, by eliminating the need for temporary piping and scaffolding and reallocating resources to more important tasks.

By focusing on more risk-significant activities, we’re able to reduce overall outage critical path time and improve personnel and nuclear safety. These savings will continue to accrue for two-thirds of all Vogtle 1 and 2 refueling outages.

While the outage savings are impressive, SNC also has the potential for $1M in cost savings when replacing safety‐related valve assemblies with valves procured as industrial grade in select applications.

The 50.69 program can be applied to other programs such as work hour rule, snubbers or any other NRC rule that has risk‐informed language. For example, Plant Vogtle will take a graded approach to the treatment of equipment in programs including equipment qualification, maintenance rule, local leak rate testing, in-service testing and inspection and procurement—with the goal of aligning the requirements of each program with the safety significance of the equipment. With these changes we expect to save several thousand man hours per year for both units.

Changing from a prescriptive, one-size-fits-all mindset to a risk-informed mindset requires a paradigm shift, not only for us but for the industry as a whole and for our regulator.

But it doesn’t need to be complicated. And Southern Nuclear is providing lessons learned that will streamline future applications. I think this can lead to renewed interest overall in risk-informed methodology.

(From left) Plant Vogtle Risk-Informed Engineering Lead Adam Coker, Supply Chain Superintendent Tom Tidwell, Operations Support Manager Steve Waldrup and Work Management Director Jesse Thomas have been instrumental in implementing the risk-informed categorization process at Vogtle. 

When we apply this science-and-performance-based process, our industry will have more resources to concentrate on risk-significant equipment, which will shorten outage durations, improve nuclear safety, simplify work, relieve unnecessary burden and reduce plant O&M and capital costs.

Additionally, use of this rule will create the proper regulatory and business environment to develop innovative solutions that will result in performance improvements.

The good news is that several utilities have joined SNC in seeking out applications using risk insights.

With this improvement in the way we integrate risk insights, the industry has the potential to make nuclear power even safer, cleaner, more reliable and more affordable. That’s why I’m calling on our industry to join Southern Nuclear in its transition to a risk-informed design, maintenance and operational framework.