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Recovery of Palladium from NPR Fuel

#0946


Development of Methods for Recovery of Palladium from Nitric Acid Solution Arising from NPR Fuel Reprocessing

Tech Area / Field

  • FIR-FUC/Fuel Cycle/Fission Reactors

Status
8 Project completed

Registration date
07.04.1997

Completion date
01.04.2004

Senior Project Manager
Kulikov G G

Leading Institute
Khlopin Radium Institute, Russia, St Petersburg

Collaborators

  • British Nuclear Fuels Ltd (BNFL), UK, Chesire, Risley Warrington

Project summary

High cost of palladium is caused by its low content in the earth's crust (5ґ10-6 %) and complicated technology for its separation and purification. Exhaustion of mineral reserves will lead to increasing the cost and will prevent the use of palladium in industry.

One of the potential sources of palladium may be concerned with the wastes of radiochemical facilities from spent nuclear fuel reprocessing.

Yield of noble metals as a result of uranium fission constitutes 0.87 kg Pd and 0.34 kg Rh per 1 t of fuel burned up to 25 MWЧd/t U. Even greater amounts are accumulated in fast reactors wherein the palladium content attains 7-8 kg per 1 t of irradiated fuel. Thus, it should be expected that the spent NPP fuel might be in the future one of the main sources of palladium and rhodium for industrial use.

Concept of recovery of inpidual fission products from spent nuclear fuel made its first appearance in the late 1950s, and the problem is still of interest to the present day.

Urgency of studies on recovery of platinum group's metals is caused by the following factors:


- high yield of fission platinoids;
- possibility of accumulating and using the metals of platinum group in technology and engineering;
- recovery of fission platinoids favors simplifying the operations for waste reprocessing by vitrification method.

With allowance for possible industrial use of reactor palladium, two essentially different directions should be noted:


1. Palladium can find use in radiochemical technology for immobilization of radioiodine or in materials for isolation of transuranium elements.
2. It is of interest to use reactor palladium in petrochemical industry (production of catalysts), in electrical technology or for afterburning of CO in auto motors.

Goal of the proposed project is wide scope of studies on recovery of palladium from nitric acid solutions arising from NPP spent fuel reprocessing.

The obtained experimental data permit to determine the most efficient methods for recovery and purification of palladium, which are suited to industrial use.

As criteria for efficiency of the processes the following factors are taken into account:


- palladium recovery must be no less than 90 %;
- purification of palladium from radionuclides of other elements must attain no less than 103 at concentrate preparation stage;
- composition and amount of reagents should not hinder further reprocessing of high-level wastes and should not considerably increase their volume;
- equipment for palladium recovery should be of standard design and meet the requirements of radiochemical industry, wherever possible.

Theoretical and experimental studies in the framework of the present project include the following section:


- analysis of available published data on the state of palladium and its behavior in fuel extraction reprocessing;
- study on palladium recovery from simulated solutions with the use of extraction, sorption, electrochemical and precipitation methods;
- choice of an optimum version and its check on real high-level solutions in hot cells.

Realization of the proposed project will allow to choose the most efficient methods for palladium recovery and purification, to substantiate the process condition and to prepare the initial data for test operations on recovery of kilogram amounts of palladium at the radiochemical plants.

We hope the results of experiments to be performed are of interest for radiochemical plants of Russia, France and Japan. Interest has been also expressed by the Lockheed Martin Idaho Technologies Company (USA).

The authors of the Project are very interested in any types of collaboration with research institutions, universities, private companies and experts of Parties the ISTC Agreement.


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