Human Reliability Analysis-Informed Insights on Cask Drops (NUREG/CR-7016, SAND2010-8463P)

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Publication Information

Manuscript Completed: November 2011
Date Published: February 2012

Prepared by:
J. Brewer,1 S. Hendrickson,1 S. Cooper, R. Boring,1

1Sandia National Laboratories
Albuquerque, NM 87185
Operated by
Sandia Corporation
for the U.S. Department of Energy

NRC Program Manager: S. Cooper
NRC Technical Lead: S. Cooper

NRC Job Code N6026

Prepared for:
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington DC 20555-0001

Availability Notice


This report documents human reliability analysis-informed insights on cask drops that may be used as an initial technical basis for activities aimed at reducing the potential for cask drops. The report provides the following:

  • Description of the analysis approach used.
  • Overview of human reliability analysis (HRA) as applied to dry cask storage operations (DCSOs).
  • Overview of human error.
  • Description of selected items from the behavioral science technical basis used in analyzing DCSOs.
  • Decomposition of DCSOs in a manner that emphasizes human performance contributions.
  • Summary of recent concerns related to handling spent fuel casks.
  • Set of terms that clarify subtle distinctions related to human performance and cask handling.
  • Set of detailed cask-handling scenarios showing various types of human performance vulnerabilities contributing to hypothetical cask drops.
  • Collection of insights on how the potential for a cask drop due to human actions may be reduced.

Although performed without the benefit of the context provided by a plant-specific probabilistic risk assessment (PRA), this report builds on previous analyses and subject matter expert interviews to provide an improved understanding of human performance in DCSOs. The study accomplished three goals: (1) investigated what should be included in a qualitative HRA for spent fuel and cask-handling operations to understand the potential for cask drops, (2) demonstrated that the qualitative analysis tasks in the ATHEANA (A Technique for Human Event Analysis) HRA method can be usefully applied to non-control room operations, and (3) began building a technical basis for potential improvements to DCSO procedures and practices to reduce the likelihood of cask drops resulting from unsafe human actions. This analysis was performed after the completion of a preliminary qualitative HRA of spent fuel handling tasks, which is documented in NUREG/CR-7017 (NRC, 2012).

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