An evaluation committee on nuclear issues was established at Japan Society of Maintenology t o discuss those issues and dispatch a report to media and self-governing body. This paper dis cusses logics of maintenance, maintenance strategy and the relation among troubles, nuclear safety, and maintenance. The report is a summary of the discussion based on expertise of JSM....
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Aims and viewpoint of evaluation committee on nuclear issues

This paper discusses maintenance optimization by the automatic planning tool for regular plant outage work in nuclear power plant using the logic programmin g language “Prolog”. As a result of consideration, the following results were obtained. (1) The automatic planning tool for regular plant outage in nuclear power plant was developed. (2) Using this tool, the work plan for BWR primary recirculation system and residual heat removal systemwas automatically made on the condition of flattening man loading o...
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A Study on Maintenance Optimization by the Automatic Planning Tool for Regular Plant OutageWork in Nuclear Power Plant Using the Logic Programming Language “Prolog”

This study proposes a technique that would enhance the sizing ability of remote field eddy c urrent testing. Numerical simulations are conducted in an axisymmetric configuration modelin g remote field inspection of ferromagnetic steam generator tube. The simulations confirm an abrupt change of measured signal, and the change depends on the depth of a defect measured....
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Remote field eddy current testing with controlled current distributions

This study develops a computational algorithm to distinguish stress corrosion cracking and fatigue cracks from signals measured electromagne tic-nondestructively. The algorithm utilizes k-nearest neighbour method, and distinguishes the two types of crack on the basis of five-dimens ional features vector extracted from the signals. Experimental verification are performed using 82 specimens including 45 artificial stress corrosion cracking and 37 artificial fatigue cracks. The results demonstarts that the a...
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Electromagnetic Nondestructive Approach to Distinguish Stress Corrosion Cracking and Fatigue Cracks

This study evaluates the size of outer race defects of ball bearings during accelerated life testing by analyzing the signal of an electromagnetic sensor. The electromagnetic sensor consists of a pickup coil wrapped around a permanent magnet. When a conductor passes in the static magnetic field, the generated eddy currents are detected as a change of the magnetic field. The autocorrelation method is applied for sizing defects in the early phase of the damage growth and the RMS method is applied for la...
英字タイトル:
Nondestructive Electromagnetic Monitoring and Diagnosis of Damage Growth in Ball Bearings