NURES® treatment for Grafenrheinfeld NPPs radioactive waste
The Grafenrheinfeld nuclear power plant, a pressurized water reactor located in central Germany, entered its decommissioning phase in 2015. Between 2020 and 2022, approximately 1,300 m³ of radioactive boric acid liquid waste from the primary circuit, spent fuel pool, and other auxiliary systems had to be managed before dismantling works could proceed. The operator of the NPP, PreussenElektra, selected Fortum to provide a solution for maximizing the volume reduction of this liquid radioactive waste. Fortum’s NURES® technology reduced the waste volume by a factor of thousand, significantly decreasing the amount of waste requiring further handling, packaging, and final disposal.
Case description
The scope of the project was to treat 1300 m3 of radioactive liquid waste arising from the decommissioning of the Grafenrheinfeld NPP. The main radionuclides in the waste stream were Sb-125, Mn-54, Co-60, Ag-100m, Te-123m, Cs-134, and Cs-137, with activities ranging from 100 MBq/m3 to 100 GBq/m3. The objective was to remove these radionuclides from the liquid, maximizing the volume of decontaminated liquid suitable for free release and therefore minimizing the amount of radioactive waste requiring further handling and disposal.
The client required a mobile, stand-alone treatment system capable of operating in parallel with dismantling activities, and additionally requested the use of a proven technology to meet disposal requirements on schedule. To comply with these requests, Fortum designed a compact NURES® (NUclide REmoval System) treatment system.
NURES®
Fortum’s patented NURES® technology purifies liquid radioactive waste. The treatment results in a radionuclide free liquid and radioactive NURES® material. The amount of radioactive waste requiring further handling and final disposal becomes a fraction of the original volume.
NURES® technology is based on 100% inorganic, highly selective granular ion exchange materials. The technology was originally developed for cesium removal process at the Loviisa NPP, but has since been further developed. The NURES® technology has been used worldwide by over 100 nuclear operators from smaller research institutes to large operating power plants.
Today, the NURES® offering includes four different ion exchangers:
CsTreat®
Based on hexacyanoferrate
Removes universally Cs isotopes
SrTreat®
Based on modified titanium oxide
Primarily removes Sr isotopes, works also for Pu and Zn
CoTreat®
Based on modified titanium oxide
Primarily removes Co isotopes, works also for corrosion products and transuranic elements
SbTreat®
Based on zirconium oxide
Primarily removes Sb oxyanions, works for other oxyanions (e.g. I species)
Our approach
The NURES® treatment system delivered to Grafenrheinfeld NPP decommissioning site consisted of a feed tank, a pre-filter, three NURES® modules, a chemical station, and a mixer tank. The prefiltering module collected suspended solids in the liquid waste, the CoTreat®, SbTreat® and CsTreat® columns removed the target radionuclides. The purpose of the chemical station and mixer tank was to adjust the pH of the waste solution, optimizing the NURES® material performance. The NURES® treatment unit was produced in Finland during the summer of 2020. The design was compact: the treatment system was assembled inside one 40 m3 room. The system was also highly automated, requiring less than 30 minutes of manual work per day. The treatment capacity of the system was up to 30 m3 of liquid a week.
The radioactive liquid treatment was completed in September 2022. After the treatment of 1300 m3 of radioactive liquid waste, all spent NURES® ion-exchange columns could be placed into one 1 m3 final disposal package, resulting in a volume reduction factor of 1300. With that, the NURES® technology demonstrated its excellent capability in treating complex liquid waste streams arising from nuclear decommissioning processes.
“The customer had a very tight schedule, as they needed to have all the liquid to be decontaminated and treated to able the continuation of the following decommissioning process. The provided NURES® system worked well and we got very good feedback from the customer.” Martin Lerche, Fortum's NURES® Product Manager.
Value added
By completing the project, Fortum’s NURES® experts gained extensive experience of the German environmental laws and regulations as well as best practices of using NURES® in a commercial power plant decommissioning project. When combined with suitable pre-treatment steps, such as selective oxidation, the mobile treatment units can address a wide variety of liquid radioactive waste streams. Their modular design also enables the system to be dismantled, transported, and redeployed to other decommissioning projects, maximizing its value across multiple sites.
"We were pleasantly surprised with the absorption capacity of the NURES® filters, since according to the planning, a significantly higher filter requirement was expected. After commissioning and completion of the trial run, the system ran reliably, without faults and with minimal maintenance." Sebastian Hahn from PreussenElektra.
