Kunihide Sasou

Team errors: definition and taxonomy

Abstract In error analysis or error management, the focus is usually upon individuals who have made errors. In large complex systems, however, most people work in teams or groups. Considering this working environment, insufficient emphasis has been given to “team errors”. This paper discusses the definition of team errors and its taxonomy. These notions are also applied to events that have occurred in the nuclear power industry, aviation industry and shipping industry. The paper also discusses the relations between team errors and Performance Shaping Factors (PSFs). As a result, the proposed definition and taxonomy are found to be useful in categorizing team errors. The analysis also reveals that deficiencies in communication, resource/task management, excessive authority gradient, excessive professional courtesy will cause team errors. Handling human errors as team errors provides an opportunity to reduce human errors.

Human Factor Analysis of JCO Criticality Accident

Abstract: The criticality accident that occurred on September 30, 1999 at a uranium processing plant in Tokai-mura was an unprecedented nuclear accident in Japan, not only because it caused deaths of two workers due to radiation casualty but also because it called for evacuation and sheltering indoors to nearby residents. The accident was not directly caused by failures or malfunctions of hardware but by workers’ unsafe action deviated from the approved procedure. It was a typical organizational accident in that several organizational factors worked behind. This article is to analyze various causal factors that lead to the accident, including situational factors of workers’ unsafe action that triggered the accident, operational and business management of the company, and nuclear safety regulation by the government. It also discusses problems of emergency response after the accident.

A Definition and Modeling of Team Errors

Rapid progress in computer technology, such as neural networks, fuzzy logic theory, artificial intelligence, etc. has brought us several support systems for use in decision-making. One example used around the world is the support systems used for the stock exchange. Not every decision-making process, however, completely relies on such support systems, people make decisions by taking into consideration the information gained from the support systems. Moreover, a decision is generally made by a group of people rather than by individuals.

Modeling and simulation of operator team behavior in nuclear power plants

This paper depicts the technique of simulation for plant operators facing abnormal events within the plant “SYBORG: Simulation System for the Behavior of an Operating Group” is installed in workstations, and simulates the behavior (cognitive action, communication) of a team consisting of 3 operators. This study introduces a “mental model” that describes and illustrates how operators predict plant behavior and make decisions to prevent the deterioration of its conditions. SYBORG simulates decision making processes via communication among operators, considering human relations such as : position, personality, credibility, etc. This paper also shows some interesting results of simulation with SYBORG.

A method for system reliability analysis with change-over operation

Abstract When fault tree analysis (FTA) is used in analysing the system reliability including human functions, the correspondence between an abnormal event and the human reaction against it may become ambiguous. In order to supplement this defect, a case study has been conducted in this research to develop a new technique termed ‘Corrective Operation Diagram Analysis’, and an attempt has been made to establish the correspondence between the reliability analysis of equipment/hardware using FTA and human reliability analysis.