Human Reliability Analysis

Purpose

Human Reliability Analysis aims to identify ways in which plant operators can intervene in the success or failure of the plant functions and systems in response to an initiating event, given the procedures for the specific plant. As it relates to advanced reactors, HRA will be a crucial element not only once a plant is operational, but also in the design and licensing phase.

Scope

Human Reliability Analysis for advanced reactors will cover operator actions that result in plant success as well as undesired end states related to human error. Since procedures for advanced reactors can vary widely between different designs and will be vastly different compared to LWR procedures, the associated operator actions will likely have high variability which will need to be addressed.

HRA

Human Reliability Assessment (HRA) is required as part of the final safety analysis report (FSAR) for any licensing application using any of the potential licensing pathways. Hamza and Diaconeasa introduced a framework for incorporating HRA in the early stages of design either at the pre-conceptual or conceptual design phase to develop significant operator actions early, thereby meeting the needs for advanced reactors in their current stage [30]. The PRA Standard for Advanced Non-LWR Nuclear (NLWR) Power Plants [6] specifies high-level and supporting technical requirements for 18 technical elements needed to create a full-scope PRA. Examples are Plant Operating States, Initiating Events Analysis, Event Sequences Analysis, Systems Analysis, and some less familiar ones such as Mechanistic Source Term Analysis, Radiological Consequence Analysis and Risk Integration. Like the ASME/ANS Level 1 PRA Standard, the NLWR Standard includes two PRA Capability Categories, CC-I and CC-II. Human actions are incorporated throughout the standard. In stakeholder interviews it was determined that a there was particular concern for the development of operator actions in response to issues that cover multiple operator shifts and for errors of commission in relation to HRA as these may not be the dominant sources of human error for current LWRs, but could become dominant for advanced reactors. Research Roadmap (EPRI 3002026495) actions that support emphasizing the importance of EoCs as a source of human error for advanced reactors:

• Develop Enhancements to Licensing Process
• Develop Industry Recommendations for Regulatory (NRC / CNSC) Guidance on Operator Staffing

A higher level of detail for these actions can be found in the report along with Table 3-2 which summarizes the methods to assess HRA’s impact on advanced reactor safety.