Akio Gofuku

A technique to generate plausible counter-operation procedures for an emergency situation based on a model expressing functions of components

ABSTRACT In large-scale engineering plants like nuclear power plants, various anomalies and accidents are usually predicted and efficient measures to minimize the damage from them have been implemented. However, when an unexpected anomaly or accident occurs, operators are asked to take flexible responsive actions to avoid its development to a catastrophic situation and to minimize the influence and damage by the accident. Considering the lessons learned from Fukushima Daiichi accidents, it is important to develop a system to support counter activities by operators and plant staff in an accidental plant condition that is not covered by emergency operating procedures prepared. The purpose of this study is to develop a technique for generating plausible operation procedures under such unexpected emergency situations. The multilevel flow modeling (MFM), a method to represent the functions of components and their relations, is applied as a framework to model functions of components. The technique uses some additional data and knowledge for deriving operation procedures. The applicability of the technique is confirmed by trial operation procedure generations for pressurized water reactor (PWR) loss-of-coolant accident cases with the conditions of some failures of safety systems.

Torque Control Method of an Electromagnetic Spherical Motor Using Torque Map

This paper describes a new method for driving electromagnetic type spherical motors that has arranged permanent magnets on a rotor and arranged electromagnets on a stator. The most significant feature of this method is, in principle, applicable to any permanent magnets arrangement and electromagnets arrangement, and it can generate torque to any direction from any rotor attitude. In the spherical motor, cogging torque between permanent magnets and electromagnets causes not only instability of rotation but also causes rotor attitude error because the rotor has three degrees of freedom. The method of canceling the cogging torque is introduced. In the case of arranging four or more electromagnets, the combination of the electric current supply becomes infinite in number and generally not determined uniquely. However, we have developed a method for deciding the electric current distribution that generates maximum torque under the limited supply of each electromagnet. In the experiment of open-loop control, it was confirmed that the rotor was able to rotate about the axes that had been set by the calculation.

Exploring risk-benefit factors of electronic clinical pathways regarding nursing communication

This study explores the influence of electronic clinical pathways (ECPs) on nurses’ daily activities, especially nursing communication, in a university hospital. Although an electronic clinical pathway enables medical-treatment processes to be standardized by interacting with different occupations, few studies have been conducted from the managerial perspective. We interviewed a doctor in the Department of Medical Information Systems and eight nurses who make entries and use ECPs. The results of the interview indicated that some nurses learned about the medical processes using electronic clinical pathways. The results also showed that the assessment abilities for patient care could decline, if the nurses failed to incorporate the electronic clinical pathways into their daily routines.

Experimental investigation of information type in plant operation manuals

Various manuals are used for plant operations and maintenance for plants. Adequate employment of manuals enables to decrease human errors in the workplace, and to ensure the quality of operators/workers performance not to heavily rely on the expertise of them. Inadequate information on manuals, however, sometimes provokes human errors. For example, it is difficult for skilled operators/workers to grasp the points of manuals if the manuals describe as over-detailed. They may be hard to recognize the information slightly different from the one that he/she acquires in his/her long experiences of the tasks. On the other hand, a novice operator or worker will make human errors if he/she uses a manual with rough descriptions of tasks because it may be difficult to understand the tasks due to his/her little knowledge and experiences for the tasks. Therefore, the information type of operation manuals should change depending on the knowledge and experiences of operators and workers for the tasks. This study experimentally investigates the relations among performance of tasks, information type of operation manuals, and skill level of operators. The results suggest that an operation manual describing concrete recovery actions for a task step by step will suit for a novice operator, while a skilled operator can use effectively the information of operation goal.