Bremsstrahlung information for the non-destructive characterization of radioactive waste packages

Project manager: Dr. Thomas Bücherl

Scientist: Dipl. Phys. Benjamin Rohrmoser

In cooperation with TU Munich, Department of Physics, E 21, Prof. P. Böni

Funded by the Bundesministeriums für Bildung und Forschung (BMBF); support code 02S8669.

 

Bremsstrahlung information for the non-destructive characterization of radioactive waste packages

 

B.Rohrmoser

Non-destructive techniques are the preferred methods for the characterization of radioactive waste packages. Compared to destructive methods it minimizes the radiation dose for the personal, the secondary radioactive waste production, and is less time consuming. In routine gamma-spectroscopy - applied successfully over decades - identification and quantification of gamma-emitting nuclides is possible. This method does not consider any information on beta-emitting nuclides embedded in the waste matrix. But there is the phenomenon of charged particle radiation called Bremsstrahlung, which may be detected in gamma scans, too. This possibility of an identification of beta-emitters is not considered in data evaluation at present. A feasibility study shall investigate, if the identification of beta-emitters in the gamma-spectra via their Bremsstrahlung is possible. First experiments have been started at laboratory dimensions. The first experiment consisted of three measurements with a high purity germanium detector (HPGe) detector. As samples 60Co, 133Ba, 137Cs and 241Am calibration standards were used as gamma-emitters and a 170Tm sample, produced at FRM II, as a Bremsstrahlung emitting nuclide. The selection of the latter was based on [1]. First, the spectrum of 170Tm only was recorded. Then only the gamma emitters 60Co, 133Ba, 137Cs and 241Am were recorded. For the third measurement all samples were measured together. Fig. 1 shows the results as well as the difference of the third to the second measurement resulting in the same distribution as the measurement of only 170Tm.