Kazunori Sasaki

A new control strategy for nuclear power reactors

A new automatic direct digital control strategy for nuclear power reactors is presented. It is based on a simple control logic of comparison between the available time (the time for the error signal to disappear) and the required time (the time for the time derivative to match that of the target trend). The method aims to control the system to an acceptable state within a minimum time under a number of restraints. The control capability of the method is shown for two typical transients. This method is generally applicable to process control in which time-optimal control based on the maximum principle is sought.

The development of the fast-running simulation pressurized water reactor plant analyzer code (NUPAC-1)

This article discusses a pressurized water reactor plant analyzer code (NUPAC-1) has been developed to apply to an operator support system or an advanced training simulator. The simulation code must produce reasonably accurate results as well as fun in a fast mode for realizing functions such as anomaly detection, estimation of unobservable plant internal states, and prediction of plant state trends. The NUPAC-1 code adopts fast computing methods, i.e., the table fitting method of the state variables, time-step control, and calculation control of heat transfer coefficients, in order to attain accuracy and fast-running capability.

Analysis of operator's diagnostic behavior using computer simulation

Computer simulation was performed on a cognitive experiment of abnormal event identification in a nuclear power plant. The process of identification has been modeled as similarity matching of symptomatic patterns and hypothesis validation by symptom observation. As a result of comparison, the simulation could explain behaviors of the subjects generally well, and some characteristics of operators cognitive processes have been revealed.

DEVELOPMENT OF ANALYSIS SUPPORT SYSTEM FOR MAN-MACHINE SYSTEM DESIGN INFORMATION

Abstract An integrated software system has been under development which aims at analyzing and evaluating the effectiveness of man-machine system designing, by computer simulations from varoius viewpoints of human factors. The target software system consists of two functional blocks: (i) distributed simulation system for man-machine interaction at man-machine interface, and (ii) man-machine design information evaluator. In this paper, the configuration of distributed simulation system is firstly introduced, followed by the explanation how operator simulator model is organized by petri net model.

Development of operator cognitive model in analysis support system for Man-Machine system design information

An integrated software system has been under development which aims at analyzing and evaluating the effectiveness of man-machine system design, by computer simulations from various viewpoints of human-factors. In this paper, the configuration of a distributed simulation system is first introduced, followed by an explanation of how the operator simulator model is organized by a Petri net model. Also presented is an example simulation of a plant anomaly diagnoses procedure using the Petri net model in its current state of development in the initial phase of software development.

Experimental Study on the Operators' Cognitive Behavior Analysis for the Plant Anomaly Diagnosis.

In this paper, a method of human cognitive state estimation based on physiological measures has been applied to the analysis of cognitive behavior during anomaly diagnosis observed with nuclear power plant simulator. This method has also been combined with the conventional experimental protocol such as operational sequence and questionnaire results. The simulator experiments have been performed using plant experts and the results demonstrate that the cognitive state estimation method can be an effective way for understanding cognitive behavior during the anomaly diagnosis of the nuclear power plant. It has also been shown from the results that the combined use of the human cognitive state estimation and the conventional experimental protocol can provide effective information in decreasing the ambiguity of the analysis results.