Session: 01-01: Robotics and Remote Handling and Viewing Technologies

Paper Number: 109783

109783 - Innovative Approaches for the Clearance Measurement of Hard-to-Reach Locations in Nuclear Power Plants - Two Project Examples 

During decommissioning of a nuclear power plant, the release of buildings from regulatory control usually involves full-surface clearance measurements, usually preceded by comprehensive cleaning. These very extensive measurement campaigns must also cover areas that are difficult to reach with ordinary measuring instruments, such as narrow gaps or high-altitude surfaces. To address this problem, a cooperation formed by Brenk Systemplanung GmbH and Tiefenbach Oberflächentechnik GmbH has successfully used different measurement technologies in combination with magnetic crawler robots. Magnetic robots of different sizes can climb steel walls and thus allow hard-to-reach places to be accessed. They also can be equipped with various instruments and can therefore be used for different tasks. In this talk, we show that clearance of mineral structures and other structure remaining in the building is possible even with limited accessibility if at least one wall is steel. We present two projects as examples of the implementation of such technologies.

The first project example is about the clearance of a gap between the spherical containment and the surrounding concrete sphere in the Stade nuclear power plant (KKS) in Germany. As the gap is too narrow for human entry and for conventional measurement equipment, the measurement strategy was adapted to the difficult conditions and the measurement technology used was specially selected for these purposes. Magnetic crawlers, equipped with respective devices, were used both for cleaning and for visual inspection of the gap. For the radiological measurements, the crawler was equipped with flat probes for total beta counting and a small-sized CsI-scintillation detector for gamma-spectrometric measurements.

In the second project example, we report on the use of larger magnetic crawlers for the release of the containment structure as a whole without prior disassembly or cutting. The project is currently ongoing, again at KKS. Its spherical steel containment with a diameter of 48 meters is measured by in-situ gamma spectroscopy at high altitudes with the help of magnetic crawlers on both the outside and the inside of the steel containment. In this project, the magnetic crawler, equipped with appropriate instruments, is also used for decoating of the steel surface.

In both cases, the innovative combination of magnetic vehicle, cleaning equipment and measurement technology was tested in advance to ensure that the planned cleaning work and measurements could be implemented in practice. The presentation deals in detail with the technology used and the results achieved.

Presenting Author: Jan Schreckenschläger Brenk Systemplanung GmbH

Presenting Author Biography: Jan Schreckenschläger studied in Cologne and Hamburg and holds a master’s degree in physics, specialized in radiation physics. In his master thesis he investigated measurement methods for the verification of nuclear disarmament using Geant4 Monte Carlo simulations. In addition to his studies, he was on the organizing team for the 2019 international NuDiVe exercise, that dealt with the practical implementation of nuclear disarmament verification. Currently, he is working at Brenk Systemplanung GmbH as a project engineer in the field of nuclear power plant decommissioning. At Brenk Systemplanung GmbH, he is involved in the planning, execution and evaluation of clearance measurements in various German nuclear power plants.