PROMETEUS is a joint research project, funded by the German Federal Ministry of Education and Research (BMBF). The focus of the R&D project lies on the development of a disposal concept for radioactive mercury and mercury-containing waste, which will be experimentally validated by the collaboration partners Forschungszentrum Jülich (Institute of Energy and Climate Research – Nuclear Waste Management) and AiNT GmbH. The aim of the PROMETEUS project is to develop a qualified method for the characterization, quantification, decontamination and disposal of mercury-containing waste in order to allow waste producers to recycle and/or dispose their residues.

Project duration: June 1^st 2016  -  May 31^st  2019

Generally, mercury-containing residues, which originate from a variety of industrial and commercial applications, pose a risk to the environment in the case of improper handling or storage. In particular, mercury, which was used in controlled areas e. g. as a sealing material in hot cells or in spallation targets, could be contaminated or activated. If no contamination or activation has occurred, the mercury can be reused. For the clearance of these residual materials, which describes the materials´ release from the regulatory control under atomic law, decision measurements are required to prove that the mass specific activity is the corresponding clearance limits (according to §§ 31-42 StrlSchV and Appendix IV).  Residual materials, which exceed those limits, must be conditioned and disposed of as nuclear waste.  

A decontamination process for non-releasable mercury-containing waste will be developed, in which the radionuclides are separated from the mercury. As a result, the separation will enable clearance of decontaminated mercury. Afterwards, the material can be recycled or disposed of as conventional hazardous waste.

Due to mercury´s high density and the resulting high self-shielding, the analysis techniques for radiological characterization must be adapted accordingly. AiNT GmbH developed a measurement facility that utilizes two semi-planar HPGe-detectors (rel. efficiency of 20 %), which are mounted on a linear actuator with opposing sliding guides and can be moved simultaneously. For decision measurement, the sample to be analyzed is placed in-between both detectors.

Radionuclides e. g. pure alpha and beta emitters, which are undetectable by gamma-spectrometric measurement, are quantified by destructive analytical methods.

As part of the PROMETEUS project, a disposal concept will be developed and validated in order to standardize the characterization, treatment and packaging of mercury-containing waste. Furthermore, it could partially be used for other water-polluting hazardous wastes. For non-clearable residual materials or the radioactive residues separated by decontamination, a conditioning process for final disposal will be developed. This requires the conversion and immobilization of mercury in a durable matrix to fulfill waste acceptance requirements for final storage.