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Safety & Performance - Inspection

The 'Inspection' team of the product group S&P carries out non-destructive inspections on pressure vessels, internals and piping in the primary circuit of both Pressurised, PWR, and Boiling, BWR, water cooled reactors.
Materials test reactors, also form a subject of in-service inspection although they are manufactured with aluminium alloy parts and are built along lines quite different from power plants.

Techniques

The in-service inspections use ultrasonic, eddy current and visual techniques to detect anomalies, also in radioactive components. Tele-manipulation and robots move the sensors quantitatively in the areas of concern. Welding joints are areas of special concern for the integrity, because of the discontinuity in the materials involved. Inspection is therefore often concentrated on the search for defects in their vicinity.

Integrated analysis

Low noise signal acquisition and the sensor location determination are coupled with the software systems for measurement and tele-manipulation control systems. The integrated analyses of both data sets allow the precise location of the defects in the structure. Mechanical engineers, software and electronics experts co-operate closely to accommodate the requirements of the client. An extra complication is that the results must not only be most accurate, but also must be obtained as fast as possible in order to limit the down time of the clients' facility to a minimum.

Testing

The in-service inspection projects preparation is located in the NRG establishment Arnhem. The section has organised the design, and assembly of the tele-manipulation equipment in the large hall, where models serve as testing ground for the qualification of the tele-manipulation and non-destructive testing sensors. The preparation of such test projects can take up to more than a year, whereas the actual testing takes usually a few days to a few weeks. The qualification bodies of the countries where the inspections will be held visit the NRG hall during the test- runs of the equipment. The test procedures are in line with the requirements of the local licensing bodies.

Projects

Examples of power plants where MMI-Inspection carries out inspections are:

Kerncentrale Borssele, Nederland
Hoge Flux Reactor Petten, Nederland
Ringhals 2,3 and 4, Sweden
Brokdorf & Biblis, Germany
Doel, Belgium

In addition to the in-service inspection, the department has another activity named EDM, electro discharge machining. This technique has been applied in various NPPs for the removal of obstructions.

Quality

The Inspection section holds certificates valid for inspection operations in the Netherlands, Scandinavia and Germany. Independently Inspection maintains internal quality systems approved by Lloyds Register, ISO9001, and SWEDAC and DAP, ISO17025.

Contact

Dr. V.A. Wichers, NRG-S&P
PO Box 25, 1755 ZG Petten, Netherlands
tel: +31 224 564656 , fax: +31 224 56 8490,
e-mail: wichers@nrg.eu

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