Evaluation of Existing Applications and Guidance on Methods for HRA – EXAM-HRA - Phase 3a Summary Report
Kent Bladh, Jörgen Frohm, Tobias Iseland, Anders Karlsson, Günter Becker, Lasse Tunturivuori, Markus Porthin, Anders Olsson, Jörg Böhm, Gunnar Johanson, Sandra Jonsson,
Are there actual differences in plant features that explain why human reliability analysis (HRA) results differ between plants for similar action or is this merely a result of differences in the HRA with respect to choice of method, analyst judgment, PSA scope, resources spent, etc.? Identifying discrepancies in HRA applications is the first step in finding these answers.
EXAM-HRA is a Nordic, Swiss and German project which assesses human reliability analysis (HRA) applications in existing probabilistic safety analysis (PSA) studies. The overall project objective is to provide guidance for a state of the art HRA for purposes of PSA, to ensure that plant specific properties are properly taken into consideration in the analysis. This shall also provide means to improve the experience feedback on plant features based on HRA and PSA results. The project is performed in several consecutive phases. The objective for the first phase is to provide a framework for identifying discrepancies in existing HRA applications. This includes development of a survey and screening process for operator actions in existing PSA studies as well as development of an evaluation guide.
The survey provides an overview of performed HRA applications, including app. 420 operator actions from six PSA studies, and constitutes basis for the selection of scenarios and actions for assessment in the upcoming phases. The case studies resulted in observations that allow for improvements of both plant features as well as the HRA itself. Additional assessments were performed on a number of operator actions in order to generate more comprehensive observations regarding both the plant features and HRA applications.
The evaluation format that has been developed within the EXAM-HRA project have been found useful and the assessments of actions performed in the case studies has resulted in findings regarding plant features as well as features of the HRA and PSA applications.
The aim is to improve consistency in in-depth HRA and human error probability (HEP) assessment by providing a common basis for methods and guidance for HRA application and assessment. These results can be used in a final stage of the project to define good practice and provide guidance for inclusion of plant specific aspects in HRA applications in the context of PSA.
Human reliability analysis, probabilistic safety analysis, operator actions