Kanji Kato

A multiprocessor system utilizing enhanced DSPs for image processing

A general-purpose image processor (GPIP) consisting of 64 digital signal processors (DSPs) in a 0.31-m/sup 3/ box is proposed to perform a wide range of image processing tasks. A high-speed DSP called DSP-i has been especially developed for this purpose. It has a highly parallel architecture with a two-level instruction hierarchy, multibank cache, and multiprocessor interface. The DSP-i machine cycle is 50 ns. A novel ring shift register bus architecture offers a flexible structure and an efficient data-exchange method for the system. Along with four proposed operation modes, it cuts the multiprocessing overhead to as little as 20%. The performance of the GPIP is 1000 MOPS (million operations per second).<<ETX>>

Noise analysis experience of a BWR power plant

Abstract This paper summarizes activities and experiences concerning noise measurement and analysis in the BWR power plant SHIMANE I since its beginning of operation, of the Hitachi Atomic Energy Research Laboratory (HAERL) in collaboration with Chugoku Electric Power Company. The possibility of using noise analysis for safety monitoring, detecting abnormalities at an incipient stage and further, diagnosing the abnormal condition is discussed. The discussion on noise sources in reactor power fluctuation during normal operation is also briefly summarized.

Multiregion Neutronics Model Based on Coarse Mesh Nodal Coupling Method for Transient Analyses of Boiling Water Reactors

A coarse mesh nodal coupling method, a well-known technique often used in steady-state neutronics analysis of light water reactors, is extended to a problem of transient phenomena of boiling water reactors (BWRs). Spatial collapse is attempted to develop a multiregion neutronics model and the associated axially one-dimensional and one-point models. These models are numerically solved through the use of two approximations, quasi-static and prompt jump. The results as applied to a reference BWR core for transient analyses, initiated by artificial thermal-hydraulic disturbances, are presented to show the practicality of the approach. The nature of the optimal weighting function necessary for the spatial collapse and for the quasi-static approximation is also discussed. Refs.

REACTIVITY BALANCE FOR REACTOR DIAGNOSIS. I. ACCURACY OF REACTIVITY BALANCE TECHNIQUE IN HITACHI TRAINING REACTOR.

The reactivity balance method commonly used for measuring inserted anomalous reactivities was applied to the HTR (Hitachi Training Reactor). The reactivities taken into consideration included the kinetic reactivity, as well as those associated with the control rod, power feedback, coolant inlet temperature and Xe buildup. The reactivity balance data were obtained to cover start-up operation, as well as at various power levels including full rated power. These results obtained show that the errors associated with power feedback and with Xe buildup reactivity are both below approximately 1¢ these errors being due to the one point approximation and to inaccuracies in the constants used in the equations. The fluctuations of residual reactivity are attributed to power fluctuations, to uncertainties in the measurement of the coolant inlet temperature and in the determination of control rod position. The scattering about the zero reactivity line caused by these fluctuations was evaluated to be within 0.8 ¢. Anom...

Maintenance work scheduling aid for nuclear power plants

A prototype system for computer-aided scheduling of maintenance work for nuclear power plants has been developed using an artificial intelligence technique. The system functions were tested by offline simulations. This system checks for interferences between maintenance tasks or between maintenance tasks and plant operations, finds isolation procedures, and makes the optimum schedule. The hierarchical plant structure data, which consist of physical and functional form knowledge, make it possible to check for interference relations even if some data are lacking. The branch-and-bound method was used for the optimum scheduling. The system configuration is described, along with knowledge-representation and inference issues.<<ETX>>

Advanced Man-Machine system for nuclear power plants—operator support functions and current developmental status

Abstract The current status of an 8-year project to develop an advanced Man-Machine System for Nuclear Power Plants (MMS-NPP), started in 1984 through support of the Japanese Ministry of International Trade and Industry (MITI), is summarized. AI techniques and multi-media communication technologies are being applied to MMS-NPP in order to provide enhanced performance of the operation support functions; for planning and monitoring plant operation under normal conditions; maintenance work planning; anomaly and accident management; and intelligent man-machine interface matching operators cognitive processes. The fundamental paradigms for the support functions are confirmed through case studies by off-line simulation tests.

Automatic Scheduling of Maintenance Work in Nuclear Power Plants

An automatic scheduling method for maintenance work in nuclear power plants has been developed using an AI technique. The purpose of this method is to help plant operators by adjusting the time schedule of various kinds of maintenance work so that incorrect ordering or timing of plant manipulations does not cause undersirable results, such as a plant trip. The functions of the method were tested by off-line simulations. The results showed that the method can produce a satisfactory schedule of plant component manipulations without interference between the tasks and plant conditions.

An automatic visual inspection method for a plastic surface based on image partitioning and gray‐level histograms

The outlook examination in fabrication of plastic products in the past has been performed mainly by visual inspection. The automation of the procedure is now considered to be important. This paper discusses a simple automatic detection method for defects on the surface of plastic electronic components such as integrated circuits. As the first step, optical properties of the defect such as flaw, pin-hole and bulge on the surface of the plastic components are discussed. This indicates problems in the detection of those defects. Then the illumination method using a planar light source is discussed to obtain a stable image against surface inclination. The procedure for practical detection of defects is developed in this paper as follows. First, to separate the image of the component surface from the background, the projection distribution of the gray-level histograms is constructed. The boundary of the component surface is extracted based on the histogram. Then the surface image is partitioned into subareas. The gray-level histogram is constructed for each partitioned subarea. Based on the maximum and the most-frequent value of the gray-level histogram, the existence or nonexistence of a defect in the subarea is determined. The experiment for the defect detection was performed using typical plastic components which are determined good or no-good. It is demonstrated that a correct defect detection can be performed for all kinds of components.

Method for detecting and removing interferences among maintenance tasks.

A method, based on AI techniques, has been developed for detecting and removing interferences among maintenance tasks in nuclear power plants. This method helps plant operators by adjusting the time schedule of the various tasks so that incorrect ordering or timing of plant manipulations does not cause undesirable results, such as a plant trip. This method consists of three main parts.(1) Checking for interference among tasks and plant conditions by analyzing effects of manipulating one component on other components.(2) Searching for a method to remove interference by isolating the problem component from the others.(3) Adding new operations and readjusting the time schedule by the branch and bound method.The performance of this method was checked by off-line simulation test. The result showed that the method can examine and remove the interferences among maintenance tasks.