SMART SIS, the Evolution of the Safey Instrument Systems

Human
Reliability Analysis for Evaluation of Conduct of Operations and Training

Erin P. Collins
and Bijan Najafi

JENSEN HUGHES

Risk
assessment and management can allow facility operators to evaluate and measure
what is actually occurring in their facilities, including the review of
processes, procedures, and events to assess human reliability.

Human reliability analysis
(HRA) is defined as a structured approach used to identify potential human
failure events (HFEs) and to systematically estimate the probability of those
events using data, models, or expert judgment. 
The probabilities used to evaluate HFEs are known as human error probabilities
or HEPs.

HRA
is most commonly performed as part of a larger quantitative risk assessment
(QRA), but can also be performed as a part of incident investigation to
evaluate the root causes for the incident and attempt to prevent their
recurrence.

The
purpose of this paper is to provide a brief overview of HRA techniques
developed in the nuclear power industry over several decades and successful
experience in applying these techniques to various industries, such as aerospace, chemical weapons destruction, HVAC system optimization, and
nuclear fuel disposal facility design.

HRA provides a
framework to evaluate, prioritize, quantify and improve the human interface
with complex systems. Qualitative analysis provides feedback to the facility
operator on the situation-specific influences (called Performance Shaping
Factors) that contribute to the success or failure of a worker action.

The
HRA process begins with an identification and definition task with the
objectives of:

·       
Identifying
the human actions involved in potential chemical release and accident
scenarios, and

·       
Defining
the HFEs at the appropriate level of detail to support qualitative analysis and
quantification. 

The analyst
conducts this initial step by reviewing the relevant incident reports,
procedures or training manuals in order to become familiar with the process and
expected actions, as well as to identify preliminary assessments of the part of
the process that could go wrong and why.

Site visits are
made to allow the human reliability analyst the opportunity to see the site and
equipment configurations first-hand and to conduct interviews with several
knowledgeable workers and trainers with significant experience. The visit begins
with an overview of the reason for the visit and the information that will be
gathered. Interview forms are developed by the analyst prior to the visit to
structure the interview process and later, to document the specific HRA-related
input information gathered from the interviews. Then, walk-throughs of the facility
are conducted to allow the analyst a clearer understanding of the worker
interfaces and the location of components, as well as visual insights on the
use of specific equipment and tools.

The information gathered through the
document review and site visits provides input to the qualitative analysis and
allows quantitative HEPs to be evaluated. 
This provides site operations with the understanding of which human
errors are most likely and how they can be prevented.

This paper will discuss the process for
evaluating human errors by obtaining process-specific information used for
qualitative and quantitative HRA.