The Gordian Knot Of Grid Resilience – Part 2

By Sherrell R. Greene

According to the Roman historian Quintus Rufus, Midas’s Gordian Knot was actually several knots so tightly entangled it was impossible to see how they were fastened.  The Gordian Knot of Grid Resilience is similarly constructed.  There’s the Fuel Security Knot (how is “fuel security” defined?)  There are a series of knots related to the definition of and engineering approach to achieving generation system resilience, transmission system resilience, distribution system resilience, and integrated Grid system resilience. There’s the Regulatory Knot – a real killer due to electricity market deregulation, entangled federal/state/local regulatory jurisdictions, and the demise of the vertically-integrated electricity provider. There’s the Ownership Knot (most Critical Infrastructure in the U.S. is actually owned by the private sector).  There’s a Tragedy Of The Commons Knot (when everyone is a stakeholder, but no one takes ownership of a problem).  I could go on.

Historians and myth keepers differ on how Alexander unloosed the Gordian Knot.  Some say he simply drew his sword and sliced it through in one fell swoop.  Others claim he exposed the ends of the knot, and then worked inward to untie each embedded knot.  It is too early to tell which approach might work for the U.S. as we move into a 21st century filled with natural hazards and malevolent human threats to our Grid.  We are probably well served to consider no single federal agency to be our modern day Alexander in the quest to untie the Gordian Knot of Grid Resilience.

So what about “resilience”, “Grid resilience”, “fuel security”, and “resilient power plants”?  How are they interrelated?  And what about current U.S. commercial nuclear power plants?  Are current U.S. nuclear power plants significant Grid resilient assets?

My short answers:  Resilience is a measure of a system’s ability to absorb, adapt to, recover from, and restore service/functionality in the wake of disruptions.  Thus, Grid resilience is a measure of the system’s ability to minimize interruptions of electricity flow to customers given a specific load prioritization hierarchy.  Fuel security (a few-to-many months of on-site fuel supply) is a discriminating attribute of nuclear power generation facilities and one that could be the attribute of supreme importance in some Grid disruption scenarios.  But fuel security is only of value when the plants that possess it are sufficiently resilient to continue to run and serve loads during and following a Grid disruption.  So… fuel security and Grid resilience are not the same thing.  A power plant can be fuel secure, but not resilient, and it can be resilient, but not fuel secure.  Resilient power generation, in the absence of resilient transmission and distribution, cannot yield a resilient Grid.

Finally, what about nuclear power plants?  Are current U.S. nuclear power plants Grid resilience asserts?  My answer to this question, along with a much more in-depth discussion of the questions and issues raised above, are contained in the lead article in this month’s (April 2018) issue of ANS’s journal, Nuclear Technology – which is freely available via Open Access .

You’ll have to read that article to learn my personal view on this question.

The time has come for a serious discussion of Grid resilience and nuclear power’s role in achieving and maintaining it!


Sherrell GreeneSherrell Greene is an ANS member, the former Director of Nuclear Technology Programs at Oak Ridge National Laboratory, and the President of Advanced Technology Insights, LLC ( ). He is a sometimes blogger at

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