Tuesday, October 10, 2017

Post # 111: Resilient Nuclear Power Plants (rNPPs) – Foundational Definitions of Resilience

I briefly discussed the concept of a “resilient Nuclear Power Plant” or “rNPP” in my last post, and offered the following definition:

“Resilient Nuclear Power Plants (rNPPs) are nuclear power plants intentionally designed, sited, and operated in a manner to enhance overall electric Grid and Critical Infrastructure resilience”.

Thus, rNPPs are defined in terms of their impact on and value to the electric Grid – rather than their size, architecture, or the particular technology suite they employ.  rNPPs might be small and modular, or large and monolithic.  The could be cooled by light water, liquid salt, helium, or liquid metal.   They could employ a thermal neutron spectrum or a fast neutron spectrum.  (This is not to ignore the fact that certain combinations of plant and reactor size, system architectures, and technologies might be more enabling in terms of achieving rNPP functionality than other combinations.  These issues will discussed in future posts.)

So, beginning with the end in mind, and working "from the outside - in," let’s first examine the fundamentals of resilience…

Resilient”.  “Resilience”.  What do these words mean?

The Merriam-Webster online dictionary provides the following definitions:


characterized or marked by resilience such as:

a.    capable of withstanding shock without permanent deformation or rupture
b.    tending to recover from or adjust easily to misfortune or change”


1.  the capability of a strained body to recover its size and shape after deformation caused especially by compressive stress

2.  an ability to recover from or adjust easily to misfortune or change.”

But, what do the words “resilient” and “resilience” mean in the context of our nation’s Critical Infrastructure?

The U.S. National Infrastructure Advisory Council’s (NIAC’s) 2009 report on Critical Infrastructure resilience is a great place to begin our examination of this question.  NIAC’s report offered a very helpful, if qualitative, definition of Infrastructure resilience:

Infrastructure resilience is the ability to reduce the magnitude and/or duration of disruptive events. The effectiveness of a resilient infrastructure or enterprise depends upon its ability to anticipate, absorb, adapt to, and/or rapidly recover from a potentially disruptive event.

NIAC’s report continues:

Absorptive capacity is the ability of the system to endure a disruption without significant deviation from normal operating performance. For example, fire-proofing foam increases the capacity of a building system to absorb the shock of a fire.

Adaptive capacity is the ability of the system to adapt to a shock to normal operating conditions. For example, the extra transformers that the U.S. electric power companies keep on store and share increases the ability of the grid to adapt quickly to regional power losses.

Recoverability is the ability of the system to recover quickly – and at low cost – from potentially disruptive events.”

“…For the purpose of this study, critical infrastructure resilience is characterized by three key features:

Robustness: the ability to maintain critical operations and functions in the face of crisis. This can be reflected in physical building and infrastructure design (office buildings, power generation and distribution structures, bridges, dams, levees), or in system redundancy and substitution (transportation, power grid, communications networks).

Resourcefulness: the ability to skillfully prepare for, respond to and manage a crisis or disruption as it unfolds. This includes identifying courses of action, business continuity planning, training, supply chain management, prioritizing actions to control and mitigate damage, and effectively communicating decisions.

Rapid recovery: the ability to return to and/or reconstitute normal operations as quickly and efficiently as possible after a disruption. Components include carefully drafted contingency plans, competent emergency operations, and the means to get the right people and resources to the right place.”

NIAC's report broke new ground and added clarity to the overall issue of Critical Infrastructure resilience.  But what about electric Grid resilience in particular?  How do these general definitions and concepts of Critical Infrastructure resilience apply to the particular Critical Infrastructure sub-Sector that is home to nuclear power plants – the electricity generation and delivery infrastructure, or, more simply, “the Grid”?

I’ll address this question in my next post.

Just Thinking,

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