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Installation for Stable Isotopes Separation

#1310


Experimental Mock-Up of Centrifugal Extractors for Stable Isotopes Separation.

Tech Area / Field

  • FIR-INS/Nuclear Instrumentation/Fission Reactors

Status
3 Approved without Funding

Registration date
26.07.1998

Leading Institute
NIKIMT (Institute of Assembly Technology), Russia, Moscow

Collaborators

  • International Atomic Energy Agency, Austria, Vienna\nLockheed Martin Corporation / Bechtel BWXT Idaho / Idaho National Engineering Laboratory, USA, ID, Idaho Falls

Project summary

The project task is the development of experimental mock-up of centrifugal extractors for the separation of stable light isotopes lithium, boron, nitrogen at al. The results of R&D work, received in the course of the development of centrifugal extractors and their utilization in a radiochemical industry, including the production of weapon uranium and plutonium will be used in terms of conversion.

The realization of the project allows also to provide the alternative employment of the part of scientists and engineers of the Institute, involved in the advancement of the centrifugal extractors for the production of nuclear materials.

Presently the separation of stable light isotopes is carried out by different methods (rectification, chemical isotope exchange, etc.) in column apparatus of large volume and height. This is very energy-consuming, ecology danger and expensive processes be-cause of the use of toxic reagents and waste problems.

The use of the solvent extraction method allows to decrease considerably expendi-tures and improve the ecology of production. In last years the large numbers of new extractants have been developed and tested for separations of isotopes Li, B, N et al. and studied for their distributions coefficients, separation factors, kinetic data. etc.

However, the lack of special multistage mock-up (100 and more stages), allowed to operate with minimum volume of solvent without phase entrainments, the solvent extraction technology in full volume has not been tested up to now. The most suitable ap-paratus for such purposes are fast centrifugal extractors.

The use of columns and mixer-settlers is possible but not effective due to:


· the large hold-up of solutions (in 50-100 times larger than in centrifugal extractors), and appropriate larger time (up to one month) of the achievement of an equilib-rium state;
· the disturbance of the equilibrium state (in columns) when process has to be stopped;
· large volume of expensive, inflammable and lightly volatile extractants;
· impossibility of the operation without phase entrainment.

It is important to note that the installation can be quickly readjusted on the separation of any isotopes and with any solvent. It is changed only the number of stages, which depends on distribution coefficients, and the installation capacity, which depends on the properties of solutions.

The extractors will be fabricated from fluorplastic in order to use any aggressive liquids.

It is very important to note that as a result of the development a geometric similarity of the main details of the extractor – prototype for production of weapon materials will be breaked. That is way the opposite attempt to create the apparatus for military purposes will have to require many years for carrying out of R & D work, as proposed in the Project centrifugal extractor for stable isotopes separations could not be served as the prototype.

As a result of the fulfillment of the Project the experimental mock-up of centrifugal extractors of the NIKIMT design comprising 100 – 150 stages will be developed. This installation will be used for the testing of the separation technology of the stable isotopes, therewith isotopes B-10 and B-11 are used as examples.

The development of the mock-up with 100 and more stages allowing to operate with the minimum volume of solutions and without phase entrainment is a rather complicated task. NIKIMT has accumulated 15 years industrial experience in operation of the cascade of the 80 centrifugal extractors in the samarium production at the plant “Polymetal”. However, the phase entrainment was from 0.5 to 1%.

The complication of the process consist in the fact that the process is not typical one which we have already assimilated. This process includes the evaporation in the solvent extraction cycle and also the withdrawal of raffinate and extract out of the middle of the cascade.

The mathematical model and programs for the calculation of the process including the effect of the phase entrainment, to calculate and develop the apparatus and multistage mock-up and experimentally confirm the ideas laid in the base of the process – all these items should be done.

The potential role collaborator

The potential role foreign collaborator consists in discussion of problems and exchange of information, obtaining during Project.


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