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Surface Decontamination by Solution

#1222


Development of Technology for Metal Surface Decontamination in Aqueous Solutions

Tech Area / Field

  • ENV-RED/Remediation and Decontamination/Environment
  • ENV-RWT/Radioactive Waste Treatment/Environment
  • FIR-NSS/Nuclear Safety and Safeguarding/Fission Reactors
  • ENV-SPC/Solid Waste Pollution and Control/Environment

Status
8 Project completed

Registration date
11.02.1998

Completion date
05.12.2002

Senior Project Manager
Gremyakova T A

Leading Institute
All-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow

Collaborators

  • Japan Nuclear Cycle Development Institute, Japan, Ibaraki

Project summary

The purpose of the project is development of universal technology for metal surface decontamination (stainless steel, carbon steel, zirconium, copper) and creation of database on metal surface decontamination with elements of an expert system. The technology is based on consecutive processing by mixture of nitric, sulphaminic and hydrofluoric acids and by acidic or alkaline solution of hydrogen pyroxide and included prescription of solutions, regulations, equipment.

The removal of radioactive pollution from metal surface by using of decontaminating solutions is one of widely used methods of cleaning. The universality of the method is caused by possibilities of removal of radioactive pollution formed as dry so wet precipitation of contamination.

The further development of liquid decontamination technology goes on a way of determination and investigation of the phenomena and processes proceeding on interface between liquid and solid phases for the technology optimization (reducing of processing time, reaching of maximum decontamination, reducing of used solutions and second radioactive waste accordingly, etc.). The basic approach for studing of complex interval processes of decontamination is experimental selection of decontaminating solutions, obtaining of empirical correlations, etc. (Tedder D.W. (ed). // Energing technologies in hazardous waste management. VII. Washington, 1995 (American Chem. Society, 7 special symposium, 17-20 Sept. 1995), p. 1215-1217, Bronson M.C., Van Konynenburg R.A., etc.; Oberhofer M., Bacelar J. // Radiation Protection in Nuclear Energy. Cons. IAEA. Vienna, 1988. p. 409-417; Decontamination and Decommissioning. (Sixteeth Water Reactor Safety Informations Meeting). – “Nuclear Safety”, 1989, v. 30, № 2, 168-170; Suva Takeshi, Goto Satoshi, Gorai Takeo e.a. // J. Atom. Energy Soc. Japan. 1988, Vol. 30, № 30. p. 1020-1029; Making the most of recycling metals – Nuclear Engineering International, October, 1996, pp. 34-35).

Decontamination of metal surface by chemical reagents is accompanied by a lot of superficial processes. They require to study of decontamination factor dependencies on local composition, structure and physical and chemical properties of the surface of processed materials.

The dependencies of the decontamination factors for radionuclides 126Ru, 137Cs, 144Ce, 60Co, 235U and 239Pu from a metal nature , temperature and structure of solutions, duration of processing will be determined at decontamination researches for stainless, carbon steel, zirconium and copper. The decontamination solution capacity mentioned and composition universality on radionuclides and materials will be value. Rates of metal corrosion in the decontamination solutions, prescription will be determined. We intend to research local corrosion (intergrain corrosion, pitting corrosion and corrosion cracking). So relative volume for liquid radioactive waste and opportunities of their processing will be determined.

It is planned to receive a rather universal way for metal surface decontamination and to create a database on decontamination methods of metals in water solutions with elements of an expert estimation. It allows to make optimum decisions under different concrete conditions.

Constructional materials of nuclear industry (stainless steel, carbon steel, zirconium and copper, including polluted by radionuclides – 137Cs, 60Co, 106Ru, 144Ce, 235U, 239Pu) will be used as objects of investigation.

The scientists of SSC RF VNIINM have unique and considerable experience at wide range of work on surface decontamination, especially by post accident work on NPP and by decommissioning works.

The universal technology for decontamination of metal surface will develope with relatively not much financial support. Taking into account the optimum conditions of the processes, which one will have in future at concrete situations, the work results to have essential financial profit.

According to the ISTC’s purposes and problems the offered project is connected with decision of ecological questions of a safe management of waste formed by processing of weapon materials and spent nuclear fuel.

The realization of the project will promote to develop of fundamental and applied researches in the field of environment save in Russia and to integrate of the Russian experts in international scientific community.

We suggest to collaborate with PNC (Japan) for discussion of the project results, investigation of PNC’s samples for estimation of the technology effectivity, development and utilization of the project results.


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