Extractants for Nuclear Decontamination
Molecular Design of Extractants to Resolve Tasks Relevant to Ecology and NPP Spent Nuclear Fuel Reprocessing.
Tech Area / Field
- ENV-WDS/Waste Disposal/Environment
3 Approved without Funding
All-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow
- Institute of Geochemistry and Analytical Chemistry, Russia, Moscow
Project summaryActivities relevant to nuclear weapons and nuclear engineering resulted in huge amounts of radioactive waste which is a serious threat to the world ecology. Significant efforts are made to decontaminate high activity level waste.
Specifically, an important task involves the partitioning of nuclear fuel cycle waste as well as extraction of long-lived radionuclides prior to waste vitrification and storage.
The most efficient method of radionuclide extraction and separation is extraction with organic agents. Extraction processes have found wide application in the radiochemical industry both for generation of weapons grade materials and NPP spent nuclear fuel reprocessing. However, the application of extraction to reprocess liquid active waste (LAW) is still at a pilot level. This fact is primarily explained by a complex composition of LAW which predetermines the use of high efficiency selective extractants. Extractants of this type are being intensively searched for throughout the world. In this case a purely empirical approach is used for which a large scope of experiments are needed.
The goal of the suggested project is a dual one. First, to develop a method of designing molecules of extractants having the desired extraction ability and selectivity on the basis of two approaches, namely, theoretical (design) and experimental ones. Second, based on the method developed to offer new high efficiency and selective extractants to isolate and separate radionuclides primarily for decontamination of high activity wastes (HAW).
The theoretical approaches involve calculations of extractant and molecule complexes by the methods of quantum chemistry and molecular mechanics followed by the synthesis and experimental check-up of extractant efficiency. The selectivityvs extractant structure (in element separation) will be studied by experimental methods by screening significant members of purposely synthesized extractants with stereochemical notionsand calculations by molecular mechanics method attracted for a preliminary selection.
The preliminary investigations carried out by the authors revealed the need in quantum-chemical calculations at highest level wich involves a large scope of computations and required an up-to-date high performance personal computers of RISC-6000 and Pentium-133 type having large memory capacity.
The basic scientific results will be a method of molecular designing of efficient and selective extractants and complexants on the basic of quantum-chemical and molecular-mechanical calculations and experimental screening. The method will be a generaized algorithm of developing, designing and experimental checking extraction reagents and in future can be used in laboratories of different countries to resolve the problems relevant to selection of efficient extractants and complex formers.
To be semi-commercially tested and subsequently commercially used not less than 3 efficient extractants will be offered for deep cleaning liquid radioactive waste of the extraction nuclear process prior to waste virification. Long lived nuclides, Pu, Np, Am, Cm will be removed and Sr and Cs that are of an important practical value will be extracted. The derived extractants will be also studied as applied to hydrometallurgical processes, extraction of metals from natural water and effluents. The use of those processes will allow to avoid the environmental contamination by radioactive and toxic substances.
Those results are deemed to be important in terms of the conversion of nuclear technologies and compliance with the tasks of ISTC.
The authors of the project invite foreign partners interested in the suggested topic for cooperation.