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Low-Waste Decontamination

#3849


Low-Waste Nonaqueous Decontamination of Work Clothes, Tools, and Soils in Ozone-Friendly Freons

Tech Area / Field

  • ENV-SPC: Environment / Solid Waste Pollution and Control

Status
7 Project terminated before completion

Registration date
01.01.2008

Senior Project Manager
Visser H

Supporting institutes

  • Mining and Chemical Complex

Project summary

The main objective of this project is the development of new procedures for decontamination, which would allow to decrease the volume of secondary radioactive wastes (especially liquid solutions). Previously we developed and examined the procedure of decontamination using dense (supercritical or liquid) carbon dioxide. This procedure allows to remove the majority of long-lived radionuclides from solid surfaces and to reduce the volume of secondary liquid wastes by a factor of 20-50 as compared to the traditional methods. However, the main disadvantage of decontamination in a medium of carbon dioxide is high working pressure comprising 10–30 and 7 MPa for supercritical and liquid carbon dioxide, respectively.

This problem can be solved using organic solutions for dry cleaning [e.g., ozone-friendly freons (OFFs)] as a medium for decontamination. In this case, working pressure can be decreased to 1 and 3-4 MPa for liquid and supercritical OFFs, respectively. Tri- or tetrachlorethylene (TCEs), which are well-known reagents for dry cleaning operating at normal pressure, can be used as model (low-boiling) systems to simulate behavior of liquid OFFs in the course of decontamination.

Along with above problem on feasibility of OFFs in decontamination, we also propose to study sorption procedures for regeneration and recycling of complexing agent and to develop new formulation of the working solutions for treatment of radioactive wastes to remove antimony and ruthenium, because known deactivation procedures do not allow removal of these radionuclides.

Hence, in the course of the project execution new nonaqueous process for decontamination of the work protective cloths, small-sized tools, and soils proceeding at technically-acceptable pressure (below 5.0 MPa) will be developed; during the process, all the most hazardous radionuclides (such as actinides, Cs, Sr, lanthanides, Sb and Ru) will be jointly removed.

The developed technologies will allow to modernize the existing industrial washing machine for dry cleaning with the aim of decontamination of radiochemically contaminated protection cloths and to design a pilot setup for decontamination in OFFs medium.

To solve the above problem we intend to:

  • study systematically the influence of water traces on the removal of radionuclide using nonaqueous complexing agent solutions;
  • search for "soft" complexing agents to remove Sb and Ru radionuclides;
  • develop the process flowsheet and mixtures for decontamination of the protective cloths and soils in TCE and OFF media;
  • study the sorption processes in OFFs and low-boiling solutions and to develop the process for recycling of decontaminating solutions;
  • modernization of existing industrial washing machine for dry cleaning for decontamination of radiochemically contaminated protection cloths in TCEs;
  • development and making of pilot setup for decontamination in OFF medium;
  • test the developed process and setups;
  • perform the feasibility study of the developed decontamination process;
  • development of business-plan for implementation of facilities for dry decontamination of the protection cloths.


The following main results should be obtained in the course of the project implementation:

  • sorption method for regeneration of nonaqueous decontaminating solutions;
  • low-waste nonaqueous process for decontamination in TCE and OFF media;
  • modernized washing machine for dry decontamination of radiochemically contaminated protection cloths and pilot setup for decontamination in OFFs medium
  • feasibility data to compare the economical effectiveness of the developed and known decontamination processes;
  • draft of the pilot setup for low-waste nonaqueous decontamination;
  • business-plan for implementation of facilities for dry decontamination of protection cloths.


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