Hydrothermal Pre-Purification for Radionuclide Solutions
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Solution Overview
Problem
Existing methods for separating radionuclides from solutions, such as those from nuclear facilities, often remove non-active nuclides in disproportionate concentrations, leading to frequent material replacement and increased costs, as they also target stable Co-60 complexes, necessitating inefficient and costly processes.
Innovation Solution
A hydrothermal process is employed to precipitate inactive nuclides like Fe, Mn, and Cr, destroying their complexes like EDTA, while sparing Co-60 complexes, followed by filtration or centrifugation, allowing for effective removal of non-active nuclides and subsequent cost-effective separation of Co-60.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ion exchangers or adsorbers are used to remove radionuclides, then radionuclides can be removed from the solution, but non-active nuclides are also removed requiring frequent material replacement
Solution Approach 1:
The invention divides the purification process into two distinct stages: first a hydrothermal pre-purification step that selectively removes non-active nuclides (Fe, Mn, Ni, Cr), followed by a second purification step for radionuclides. This segmentation allows each stage to target specific contaminants, preventing the saturation problem that occurs when using a single purification method for all contaminants.
Solution Approach 2:
The hydrothermal pre-purification is performed as a preliminary action before the main radionuclide removal process. By destroying complexes of non-active nuclides and precipitating them out in advance, the subsequent ion exchange or adsorption processes only need to handle radionuclides, significantly extending the operational life of the purification materials.
2Quantity of substance
If Co-60 complexes are targeted for removal, then radionuclide contamination is reduced, but the process requires frequent material replacement due to co-removal of non-active nuclides
Solution Approach 1:
The invention applies different treatment conditions to different types of complexes in the solution. The hydrothermal pre-purification specifically targets complexes of non-active nuclides (Fe, Mn, Ni, Cr) with destruction temperatures below 220°C, while leaving the more stable Co-60/EDTA complex intact. This selective local quality approach ensures that only the intended targets are affected.
Solution Approach 2:
The invention utilizes parameter changes, specifically temperature and pH, to achieve selective destruction of complexes. By controlling the temperature to remain below 220°C and adjusting pH to ≥7, the process selectively destroys less stable complexes of non-active nuclides while preserving the stable Co-60/EDTA complex, enabling subsequent efficient radionuclide removal.
3Productivity
If harsh methods are used to remove radionuclides, then removal efficiency increases, but organic components and stable complexes remain intact causing additional contamination
Solution Approach 1:
The invention converts the stability of Co-60/EDTA complexes, which initially appears as a problem preventing efficient removal, into a benefit. By using mild hydrothermal conditions that do not destroy this stable complex, the process avoids generating additional contamination from breakdown products, while still effectively removing non-active nuclides in a pre-purification step.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method significantly reduces non-active nuclide load, enabling more efficient and cost-effective subsequent radionuclide removal processes by selectively precipitating and removing inactive nuclides, thereby reducing material replacement needs and operational burdens.
Implementation Method 1
citrate, oxalate or EDTA complexes of Fe, Mn, Ni and Cr are destroyed in the hydrothermal process and precipitate as hydroxides
Implementation Method 2
exposing the solution in a pressure vessel to a temperature T of, in particular, 150°C ≤ T ≤ 220°C
Implementation Method 3
The set temperature in the pressure vessel simultaneously builds up a pressure of approximately 1.5 MPa
Implementation Method 4
precipitate as hydroxides, which are then removed from the solution e.g. by filtration or centrifugation
Implementation Method 5
precipitate as hydroxides, which are then removed from the solution e.g. by filtration or centrifugation
Data Source
AI summary
The invention relates to a method for pre-purifying solutions containing radionuclides, such as Co-60, such as evaporator concentrates of nuclear power plants, by precipitating non-active nuclides in a hydrothermal process and subsequently separating the precipitated solids.