BITUMEN PYROHYDROLYSIS | RADWASTE MANAGEMENT
the technical readiness of the process and its application. Since the demonstrator unit should also serve as a pilot plant for the treatment of bituminized waste it is crucial that radioactive bituminized waste can be treated at the facility.
Selection criteria for the site include:
● Licenced to work with radioactive material ● Permission and logistics capability to handle and treat
radioactive waste, including bituminized radioactive waste
● Space available for the demonstrator facility ● Ability to discharge treated off-gas, preferably with an
existing post-combustion system with a connected off- gas treatment system
Above, figure 3: The lab-scale furnace as installed
treatment. In addition, residues on the outside of the drum dust could be seen, which had been deposited during the pyrohydrolysis process itself. By adjusting the temperature profile as well as the amount of steam used within the process the deposits could be removed completely. However, the tests showed that part of the drained bitumen, which is collected in a drip tray below the 30-litre drum, still remained (see Figure 4). The test programme will continue in 2022 by adjusting
the steam flow to further reduce the remains in the drip tray. In the meantime, 30-litre drums were filled with salt or ion exchange resins embedded in bitumen matrix to simulate bituminized radioactive waste packages. Following the promising results from the lab-scale tests, NUKEM Technologies decided to go ahead with the next phase in the R&D programme and is seeking a partner to support the development a demonstrator unit. Ideally, the demonstrator unit should be installed at a facility with an existing bituminized waste plant or research centre that is licenced to work with radioactive materials. The aim is to use bituminized waste from existing stocks to demonstrate
Next steps to pyrohydrolysis of bitumenized wastes Bituminized radioactive waste seems to be at least partly excluded from disposal at deep geological repositories. Owners of these waste packages are therefore seeking alternatives to re-conditioning of these waste materials. Most of the established methods require the pre- treatment of the waste package – draining the bitumen from the packages – as the downstream processes are not capable of treating the complete waste packages. When draining bitumen prior to treatment significant amounts of bitumen remain in the waste package which will also contain radioactive materials from the original embedded radwaste. Due to the properties of the bitumen, such as its viscous and sticky characteristics, further handling of the drained waste packages within glove boxes is required. This forms another problematic step in the treatment of the bituminized waste packages. The pyrohydrolysis process seems to be a promising
technology to safely reprocess complete waste packages with bituminized radioactive waste without the need for draining first. The first test with 20 kg bitumen treated in a lab-scale furnace showed very good results in mass/volume reduction. After further optimisation, the already high mass/ volume reduction should increase. The next phase will be to develop a full-scale demonstrator to prove the reliable operation of the pyrohydrolysis facility and target TRL 7. Other targets of the demonstrator unit include producing a reliable set of operational and design parameters enabling precise calculation of investment and operational cost of an industrial-scale facility. ■
Above, figure 4: Inside and outside view of the 30-litre drum after pyrohydrolysis test as well as dust remains in the drip tray
www.neimagazine.com | August 2022 | 39
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