Integrated Human Event Analysis System for Event and Condition Assessment (IDHEAS-ECA) (NUREG-2256)

On this page:

Download complete document

Publication Information

Manuscript Completed: July 2022
Date Published: October 2022

Prepared by:
J. Xing
Y.J. Chang
J. DeJesus Segarra

Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Availability Notice


This report describes a human reliability analysis (HRA) method developed by the U.S. Nuclear Regulatory Commission (NRC) staff. The method is known as the Integrated Human Event Analysis System for Event and Condition Assessment (IDHEAS-ECA). It is based on NUREG-2198, "The General Methodology of an Integrated Human Event Analysis System." IDHEAS-ECA supports risk-informed decisionmaking by providing an HRA method to be used in probabilistic risk assessment (PRA) applications. The NRC staff uses PRA in the review of risk-informed license amendment requests and evaluations of notices of enforcement discretion, operational events (e.g., Management Directive 8.3, "NRC Incident Investigation Program," and the accident sequence precursor program), and inspection findings (i.e., the significance determination process). IDHEAS-ECA was developed because, in recent years, the scope of application of HRA has expanded into situations beyond the scope of existing HRA methods.

IDHEAS-ECA is intended to apply to the same situations modeled by existing HRA methods (e.g., nuclear power plant internal events while at-power) and beyond (e.g., external events, low power and shutdown events, and events for which flexible and coping strategies (FLEX) equipment is used). The IDHEAS-ECA method provides step-by-step guidance for analyzing a human action and its context. It models a human action by using five macrocognitive functions: detection, understanding, decisionmaking, action execution, and interteam coordination. The failure of a human action is modeled with a set of cognitive failure modes and performance-influencing factors, which are then used to calculate the human error probability (HEP). The IDHEAS-ECA method includes a software package that facilitates the documentation of the analysis of a human action and its context and uses the results of the analysis as input to calculate the HEP.

The report also provides additional information in the appendices, which include (1) a worksheet for analyzing and modeling human actions and their context, (2) the integrated human error data needed to calculate HEPs, and (3) two examples that demonstrate the use of the IDHEAS-ECA method. This report replaces Research Information Letter 2020-02.

Page Last Reviewed/Updated Tuesday, November 08, 2022