Safety-related aspects and the targeted high availability of the power plant as well as the requirements stipulated by Swiss regulatory authorities prompted the operator of NPP Leibstadt (KKL) to introduce a procedure for the early identification of susceptible piping sections and components due to flow-accelerated material degradation mechanism.

In order to deal with the flow-accelerated corrosion issue, the NPP Leibstadt (KKL) adopted the computer code COMSY for the preparation of targeted wall thickness inspection programs.

In a first step a systematic screening procedure was applied with the intension to reliably identify system areas which may be subject to a flow-accelerated corrosion attack. For system areas sensitive to degradation a detailed lifetime analysis was performed for individual piping elements. Based on the predicted service life, elements were priorized for inspection programs. The results of examination were fed back to further optimization of the lifetime predictions.

Due to systematic approach applied, a significant gain of knowledge be achieved regarding the impact of FAC on a plant-wide basis. The combination of predictions, the measured data and other inspection results (e.g. visual examinations) are used to prepare a catalog of weak points. The weak-point catalog is thus a tool for as-is information and inspection of piping systems / components. It serves to optimize the condition-oriented planning of future measures and inspections and will be revised and updated on an annual basis.

          Mr. André Zander works for AREVA NP GmbH as an project manager in the field of thermal hydraulics and plant life management. After achieving a diploma in energy engineering in 2001, he was active on programming and diffrent project of ageing and plant life management activities.