NUKEM Technologies has established a R&D program for treatment of bituminized waste stored in drums.
Today, bituminized radioactive waste in most cases does not meet the acceptance criteria for long-term disposal in deep geological repositories. Most of the established re-conditioning methods require pre-treatment of the waste packages by draining the bitumen from the packages, because the downstream processes are not capable of treating whole waste packages. When draining bitumen from waste packages prior to the treatment of the bitumen itself, significant amounts of bitumen will remain in the waste package. These will also contain activity from the originally embedded radwaste. Due to the properties of bitumen, which is sticky, further handling of drained waste packages in glove boxes results in another problematic step in the treatment of bituminized waste packages.
In the past NUKEM Technologies has already executed a number of tests at the University of Freiberg, with DBI-Virtuhcon, showing the suitability of pyrohydrolysis in principle for the treatment of bituminized waste packed in whole drums. The results of the conducted laboratory tests were used to develop a conceptual idea for the treatment of drums containing bituminized radioactive waste. These results became the foundation for the related R&D activities. In 2020 NUKEM Technologies launched the R&D project “Pyrohydrolysis of Bituminized Waste”. The project is divided into two major phases, the lab-scale facility processing up to 30 kg of simulated bituminized waste and the demonstrator plant capable of treating one 200-liter drum per batch. The project was started with the lab-scale facility.
The first step was to design and procure a lab-scale furnace able to process 30-liter drums containing simulated bituminized waste. At the beginning of 2021 the furnace was delivered to DBI Virtuhcon, where it was successfully installed and commissioned.
In parallel with the lab-scale facility activities, drain tests with 400 ml canisters filled with pure bitumen were performed to investigate the behavior of bitumen and to simulate the necessary pretreatment step for alternative treatment methods, such as co-incineration.
For the drain test the canisters were punched around the circumference through the whole vertical extent of the bitumen filling. After that the canisters were slowly heated up with a heating rate of 10K/min to a temperature between 100 and 180 °C. The results obtained should serve as a benchmark for the pyrohydrolysis.
After successful installation and commissioning of the lab-scale furnace first tests were performed using pure bitumen.
As a first phase of the lab-scale furnace test program the so-called “approach-tests” were performed to define the temperature profile and to get first impressions on the behavior of the bitumen in larger amounts. The first test with 20 kg bitumen treated in the lab-scale furnace showed very good results in mass / volume reduction. After further optimizing the operational parameters, such as steam and temperature profile, the already high mass / volume reduction should be further increased.
Receiving promising results from the lab-scale tests NUKEM Technologies decided to go ahead with the next phase in the R&D program. The construction of the demonstrator plant is scheduled to take place in 2022, based on the achieved results from the lab-scale phase.
The pyrohydrolysis process seems to be a promising technology to safely reprocess complete waste packages with bituminized radioactive waste without the need for prior draining.
NUKEM Technologies in Karlstein am Main, Germany, is world-wide active in the areas of management of radioactive waste and spent fuel, decommissioning of nuclear facilities, engineering and consulting. For more than 60 years NUKEM Technologies provides high quality products, technologies and services, where Innovation, Solutions and Excellence are closely linked.
Contact:
Yvonne Amend
NUKEM Technologies Engineering Services GmbH
Zeche Gustav 6, 63791 Karlstein am Main
Tel: +49 6023 91-1321,
E-mail:
www.nukemtechnologies.de
