Decontamination of spent fuel pool water using a NURES® filled plate filter

Introduction

Fortum conducted a feasibility study together with RWE Gundremmingen nuclear power plant in Germany with a focus of decontaminating spent fuel pool (SFP) waters as a part of their decommissioning activities. The main objective was to investigate various options for the treatment ranging from a full scale treatment facility to a very robust and cost efficient solution yet providing sufficient decontamination. The incentives from the customer’s side was to apply the best available technology and decrease the amount of activity released to the environment in a cost effective way. Therefore, the option of using existing equipment was attractive to the customer and prioritized in the study, and the focus was put on testing the technical feasibility of a plate filter setup at the plant. The main contributors to the SFP activities were Cs-137 and Co-60 and therefore, NURES® CsTreat® and CoTreat® were selected to be used in the tests. The study resulted in successful treatment of about 100m3 of contaminated SFP water in a matter of days. The activity was decreased to a low level were the treated liquid could be released to the environment. 

Key Highlights

• Spent fuel pool decontamination 
• High capacity 
• Robust and fast treatment with high performance 
• Significant cost savings

New configuration for using NURES® materials

The first part of the project was to shortlist the option based on the project objectives and discussions between Fortum and Gundremmingen. The most promising option was to use an existing plate filter at the site. The plate filter had been previously used for purification of waste liquids with organic resins. The plate filter configuration had not been used before in NURES® treatment and therefore, this project provided a unique opportunity to test the ion exchange materials in an unconventional setup. The plate filter enabled the circulation of the SFP water through with 5 L/s flow rate and was filled with diatomaceous earth filler topped with NURES® ion exchange materials.

Large scale testing for proof of concept

After preliminary laboratory scale testing which demonstrated the efficiency of the NURES® materials in the SFP water decontamination, the plant approved testing the technology in an industrial scale.  The large scale tests were conducted by filling the plate filter with NURES® material and circulating about 100m3 of SFP water through the filter while monitoring the decrease of the activity concentrations over time. First, the plate filter was filled with NURES® CoTreat® to remove Co-60, followed by CsTreat® for removal of Cs-137. The removal of Co-60 was slightly slower compared to the removal of Cs-137 and the circulation was continued for several days where as sufficient cesium removal was achieved after a couple of days recirculation. This is likely due to the differences in the molecular structure of the different NURES® materials affecting the sorption kinetics. Ultimately, over 94 % of cobalt and over 97 % of cesium activities were removed from the SPF liquid and the treated liquid was control released to the environment. 

Summary

The large scale test demonstrated the technical feasibility of NURES® treatment for the SFP water at Gundremmingen NPP. Sufficient decontamination was achieved, however, even more efficient performance can be reached with further optimization. The treatment of the Gundremmingen SFP water with the plate filter configuration provides significant cost savings in operational and disposal costs, and decreases the environmental impact of radioactive liquid waste treatment by lowering the amount of radioactivity released to the environment.

 

NURES® shows great potential for our future needs. It was a real pleasure to work together with the Fortum experts. This synergy between old and new enables us to develop sustainable and efficient approaches to improving water quality. We are proud to work together on the future of water management and make a positive contribution to environmental protection – says Conrad Schröder, manager at the RWE Gundremmingen, radioactive chemistry department.