1: Characterize Critical Loads for Risk Assessment
Risk Assessment / Characterize Critical Loads for Risk Assessment
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Inputs Needed

  • Criticality weighting factors for critical functions from Action 4 in the Site Level Planning module
  • Redundant system data from Action 3 in the Baseline Development module
  • List of critical loads and the critical functions they support from Action 2 in the Baseline Development module


  • Documentation of critical function duplication capability, including time to initiate, and duplication testing and procedures
  • Input to inform development of solutions in Action 2 of the Solution Development module
  • Input to risk screening tool


The purpose of this activity is to finish characterizing the critical loads, identified in the Baseline Development module. This includes determining which redundant systems that support the critical loads would be the first to be used and which ones are secondary (i.e., will only be used if there is a failure of the first redundant system). Additionally, for some critical functions a site may have means for temporarily maintaining functionality without reliance on the critical load. These factors influence the contributions of critical loads to risk.


This action consolidates information that has been collected in previous modules to better understand risk scenarios of concern on a load-by-load basis. Critical loads were identified and analyzed in the Baseline Development module. Here, this information is brought together with additional data from mission owner interviews.

Complete the Risk Assessment Action 1 Worksheet: Critical Load Characterization

Determine Function Duplication Capability

A key activity in determining the risk of energy and water disruptions is to determine whether the capability exists to duplicate the function supported by the critical load. What alternatives currently exist that will duplicate the function elsewhere? How long does it take that capability to initiate? How confident is the site that such duplication will work as planned? For example, can the staff who would normally provide real-time intelligence analysis in the office facility be relocated to another facility in the event of power loss? How long would that relocation take? Critical function duplication can help reduce the consequence of resource loss by ensuring the critical function continues—even without the critical load. Record the answers to these questions in this Action’s worksheet.

Designate First and Second Redundant Energy and Water Systems

In addition to critical function duplication capabilities, critical loads may also have one or more redundant energy and water systems that enable operation in the event of primary system outages. Redundant systems were characterized in Baseline Development Action 3. Here, designate redundant systems that supports each critical load as the first or second redundant system. Note that additional redundant systems (i.e., third, fourth, etc.) are not modeled in the TRN. This is because the streamlined TRN model does not include the detailed analysis required to account for common cause failures that may diminish benefits associated with additional redundancy. This means that modeling additional redundant systems would be likely to give too much credit given the probability that a similar (or the same) characteristic that could lead to the failure of the first or second redundant system would also lead to a failure of subsequent redundant systems.