Qualification and evaluation of promising methods for early detection of defects and reduction of radiation doses to personnel performing recurrent inspections of safety-relevant piping systems; testing the performance of the potential drop method. Parts A and B. Development of belts for rapid installation of a defect monitoring and measuring field and measured potential distributions at regions of dissimilar wall thickness and dissimilar welds. - Calculated results of potential distributions at regions of dissimilar wall thickness and dissimilar welds with and without flaws, and comparison with measured results

Under the SR 2045 and SR 2045/1 projects the tests for applying the advanced potential drop method in recurrent inspections in nuclear power plants are continued. The project is chiefly aimed at optimising and improving the early detection of defects and flaws in piping systems during the customary periodic inspection. The potential drop method which has been refined for this purpose can preferably be applied as an additional alternative in places and under conditions where it is difficult for orthodox methods to detect and monitor defects and flaws in materials. As a non-destructive method, the potential drop method is almost unrivalled when it comes to continuously monitoring indications, findings and areas of the material for crack formation and crack growth (even at service temperatures). And here it was possible to achieve an appreciable success: A potential drop measuring field is now much faster to install than before thanks to the belts developed. This is of particular advantage in areas of increased radiation levels. Moreover, comparative calculations by means of the MAFIA Finite Difference Programme have proved that the calibration and interpretation of measured values obtained from ferrite/austenite weld joints, weld joints between components of different wall thickness and intricate structures can be considerably improved by such calculations. (orig.)