Proof of suitability of Ca-41 as a reference isotope for the characterization of reactor concrete

Richard Spanier1, Matthias Dewald1, Björn Dittmann1, Stefan Heinze2, Markus Schiffer2, Susan Herb2, Claus Müller-Gatermann2, Gereon Hackenberg2, Alexander Stolz2, Alfred Dewald2, Raphael Margreiter3, Erik Strub3, Marco Michel3, Klaus Eberhardt4

1Gesellschaft Für Anlagen- Und Reaktorsicherheit (grs) Ggmbh, Cologne, Germany, 2Institute for Nuclear Physics, CologneAMS, University of Cologne, Cologne, Germany, 3Department of Nuclear Chemistry, University of Cologne, Cologne, Germany, 4Institute for Nuclear Chemistry, Mainz, Mainz, Germany

In the field of nuclear waste management, reference nuclides are important for the radiological characterization of the radioactive material. Commonly used reference nuclides are e.g. Co-60 or Eu-152 because they can be easily quantified by gamma ray spectrometry. In case of Co-60 the relatively short half-live of 5.3 a might be a major disadvantage as decommissioning works might take place on a longer timescale. Thus, it is not very well suited if longer storage and control is needed. Another disadvantage in the case of reactor concrete is that they are generated by neutron irradiation of Co-59 or Eu-151, respectively, which both are contained only as trace elements with an unknown level of homogeneity.

This research project therefore investigated the suitability of Ca-41 as a reference isotope for the characterisation of reactor concrete, e.g. originating from the bio-shield of a nuclear power station. For this purpose, several samples of concrete material were irradiated with thermal neutrons with different doses at the Mainz TRIGA reactor. The irradiated samples were then measured by gamma spectroscopy and the Ca-41 was chemically extracted as CaF to produce a sputter target for the AMS measurement. Subsequently the Ca-41 concentration was determined at the 6MV TANDETRON AMS set-up, “CologneAMS”, of the University of Cologne.

We will report on the results with respect to sensitivity and precision obtained so far.

Supported by Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) under contract No.: 3617R01364-UA3413

Samples were partly supplied by KTE (Kerntechnische Entsorgung Karlsruhe)



My name is Richard Spanier. I have been working, as an expert in the field of decommissioning, at the Gesellschaft für Anlagen und Reaktorsicherheit (GRS) gGmbH (Germany) in the Decommissioning and Storage Department since 2019. GRS is a technical support organisation and mainly works on behalf of the German federal government, answering technical and regulatory questions. Before that, I graduated from the University of Cologne (Germany) with a doctoral degree in experimental physics for which I mainly focused on accelerator mass spectrometry. This technique I used to investigate reactor concrete.

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Nov 08 - 19 2021