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Deactivating Polymeric Compositions

#A-1243.2


Elaboration of New Highly Effective Polymeric Compositions on Water Basis of Multifunctional Significance, Providing Reliable Protection, Localization and Isolation of Different Surfaces from Radioactive Pollutions

Tech Area / Field

  • ENV-RED/Remediation and Decontamination/Environment
  • CHE-POL/Polymer Chemistry/Chemistry

Status
8 Project completed

Registration date
04.09.2007

Completion date
22.02.2012

Senior Project Manager
Savinova N V

Leading Institute
Yerevan Institute "Plastpolymer", Armenia, Yerevan

Supporting institutes

  • The Scientific Centre of Radiation Medicine and Burns, Armenia, Yerevan

Collaborators

  • Ecole Polytechnique de Montreal, Canada, QC, Montreal

Project summary

Development of nuclear energy and nuclear technologies is closely connected with the solution of a number of problems, providing safety of exploitation of the objects of nuclear engineering, as well as environment protection (EP). EP assumes neutralization of radioactive waste at all the stages of nuclear technologies and protection of nuclear engineering objects and people from radioactive contamination (RC).

One of the EP methods is deactivation (decontamination), which is removal of RC from the surfaces of different objects or reduction of their level.

It is difficult to over-evaluate the volume of deactivation works of RC sources, as deactivation is carried out as scheduled (routine) events, and also used for preliminary processing the objects which are a subject recycling and neutralization, as well as in cases of local and scale outages.

One of the well known methods to decontaminate surfaces is deactivation with strippable polymeric coatings which have incontestable advantages as compared with other methods of deactivation:

  • small amount of solid waste;
  • exclusion of liquid radioactive waste, requiring additional secondary processing.

Deactivation efficiency depends on many parameters such as the level of contamination, the size, concentration and composition of RC, the nature of contaminated surface, location of radio-nuclides (surface and depth contamination), etc.

Decontamination processes of the objects of nuclear engineering were used and developed along with the development of nuclear energy. But these processes have got a huge impulse after Chernobyl NPP accident. Along with the known deactivating materials and methods, new ones were urgently developed taking into account the scope of deactivating objects, covering a set of radio-nuclides and their type, as well as variety of surfaces. Namely Chernobyl experience revealed close interrelation between the types of radio-nuclides and their ability to be adsorbs on different surfaces, influence of various ways of deactivation on its efficiency, which essentially depends on type of surfaces and the mechanism of binding. This knowledge has been a guide to differentiation of deactivation problems, in particular, to more purposeful studying of attracting and binding mechanisms. In large scales in Chernobyl the polymeric compositions (both in organic solvents and water-based) were applied. However unprecedented scales of Chernobyl deactivation works revealed the necessity of expanding deactivating compositions types and grades.

Currently, the urgency of this problem is increasing. First of all, in spite of development of alternative sources of energy, nuclear energy is considered to be one of the most promising and developing fields. Secondly, taking into consideration the fact that the first NPPs were constructed and started their exploitation more than 40 years ago, many countries face the problem of closing up the old NPPs, de-assembling the equipment and creating new reactors, as well as construction of new NPPs.

Analysis of the publications in this field revealed that according to the forecasts these activities will reach their peak in 2010-2040.That is the reason that the variety of deactivating processes and the volume of decontamination is being expanded and it will still go on in the nearest future.

Deactivating compositions on the basis of organic solvents alongside with positive performance (fast drying) also have the negative ones – flammability risk and environmental contamination by toxic products. These lacks get special value at indoors deactivating works. Chernobyl experience has shown efficiency of deactivation of various surfaces by water-based compositions and by that – the great potentiality in further widening of a scope of polymeric compositions in water and water –dispersion medium.

State of the artcurrently there is a number of the industrially produced polymeric deactivating compositions on the water basis. From the point of view of polymeric systems they represent both solutions, and dispersions. However there are no data on deactivation mechanisms, impact of the polymers characteristics (MW, MMD, degree of branching, functionality, etc) over the properties of composition and deactivation efficiency. In publications, regarding to comparison of coatings properties the main compared parameters are an easy of application and removal, decontamination efficiency, productivity and unit costs. As a rule the total α- and/or β,γ- contamination is specified, but the selectivity according to radio-nuclides is not investigated.

Objective of the proposed Project is development of new polymeric deactivating coatings on water and water-dispersion bases taking into consideration the full complexity of the following issues (conditioned by the type of nuclear-energetic facilities):

  • the level of contamination
  • the set of radionuclides and their selective removing (i.e. revealing the decontamination mechanism depending on certain conditions)
  • the type of surface deactivated
  • the methods of coatings application
  • the terms of coatings exploitation (temperature, humidity, etc.)

Novelty of the proposed developments is provided by using new initiating systems and new technique in synthesis of copolymers and compositions, developed by the project researchers in the previous ISTC projects.

The basis for implementation the proposed activities are as follows:

  1. Deactivating polymeric compositions developed earlier. The manager of the proposed project G. Harutyunyan works in the field of development of polymeric deactivating coatings for a long time. These coatings have passed successful industrial tests at the Khmelnitsk, Kolsk and Armenian NPPs. Some of them were used to produce and apply large-tonnage compositions in such critical accidents as Chernobyl and a Pacific navy nuclear submarine.
  2. The new investigations and the results received by the project scientists during implementation of previous ISTC projects. These new results include the synthesis methods of vinyl acetate copolymers, vinyl alcohol and other co-monomers with a various set of functional groups and molecular characteristics, as well as development of polymerization systems to obtain such copolymers with new properties.
  3. The results of the project A-1243 PDG, funded by Canada and implemented by the project participants during the period of February-July 2007.

Expected Results and Their Application

The proposed research belongs to categories: applied research, development.


1. Applied research


Proposed researches carry out in the interests of industrial technologies of vinylacetate and polyvinylalcohol (co)polymers production and address improving the existing ones.

New initiating system and technological methods will be developed and used for bulk, water-solution and water-dispersion copolymerization processes.

Prospective benefits from use of the developed processes (in comparison with existing analogues):

  • economic (decreasing of synthesis temperature, reduction of processes technology stages),
  • ecological (development of water systems as polymeric covering),
  • production of products with new properties (obtainment of copolymers with well-defined structures – molecular masses, functionality, degree of branching, etc.).

Carried out researches have both own independent value, and will be used in the project in a category development.


2. Development


The major development outcome will be new polymeric systems to produce strippable deactivating coverings.

The basic potential users of development can be manufacturers of similar polymeric systems and further as final consumers- objects of nuclear engineering.

The possible scenario for technology implementation and products manufacturing at the industrial level:

  • identifying possible partners-manufacturers of similar products during the performance evaluation trials of the project;
  • joint works to produce experimental batches of products with more precise definition of technologies and completion of the technical documentation;
  • most preferred approach: -creation of a joint venture; or sale of licenses.

Protection of intellectual property using patents applications (or know-how).

Meeting ISTC Goals and Objectives

  • The Project will allow scientists that were earlier engaged in weapons development, to carry out scientific research for peaceful purposes.
  • The scope and the level of the proposed research require an international cooperation of scientists (first involving collaborators) and laboratories conducting similar studies.
  • The Project includes applied researches in area of vinylacetate and polyvinylalcohol copolymers technology and development of new polymeric materials for peaceful purposes (strippable deactivating coverings for environment protection and nuclear safety).
  • The marketing studies at the very beginning of the Project will be an evaluation for the potential of proposed "products" from the point of view of the market acceptability. For each product, a niche will be identified and appropriate steps will be taken towards commercialization.

Scope of activities
  • Synthesis of of vinylacetate (co)polymers with other vinyl monomers by using of the new initiating systems in water solutions and water-dispersion medium.
  • Investigation of developed co-polymers, their water solutions and films (functional structure, MM, MMD, viscosity of solutions, surface tension, limiting wetting angle, films physical-mechanical properties, strippability form different surfaces).
  • Model investigations of binding (fixation) mechanisms of non-radioactive elements with polymeric compositions.
  • Compositions preparing, investigation of compatibility of some polymers with modifying and plasticizing components. Determination of rheological properties of compositions , viability, frost-resistance, strippability from different surfaces.
  • Assessment determination of deactivating and toxicological properties of optimal samples in CTOBR.
  • Manufacturing of pilot samples of co-polymers and compositions. Investigation of deactivating characteristics of some samples in industrial conditions at Armenian NPP.
  • Selection of the commercialization variants of project outcomes.

Role of Foreign Collaborators/Partners
  • Exchanging scientific results through joint discussions, joint publications and participation in conferences, symposiums
  • Joint tests of some elaborated products. The project collaborator has agreed to commit resources from his laboratory to assist in polymers characterization, using rheological and gel permeation investigation techniques.
  • Direct visit to participant- institutes of the project to discuss the results of the implemented activities.

Technical Approach and Methodology
  • Synthesis of (co) polymers through methods of radical copolymerization in the water and water-dispersion medium by using of various initiating systems (red-ox, ATRP).
  • Determination of characteristics and properties of the obtained (co) polymers (functional composition, molecular weights, viscosity, рН, etc.) by using of methods of the chemical analysis, IR-, NMR-, UV-spectroscopy, viscosimetry, size exclusion chromatography.
  • Study of water solutions (viscosity, the size of particles and high-molecular formations depending on concentration, surface tension, critical concentration of micelle formation, limiting wetting angle, etc).
  • Preparation of compositions with introduction in solutions and dispersions various plasticizers and modifying additives. Definition of film-forming properties of solutions, dispersions of polymers and compositions (duration of film formation, thickness, strip ability from various surfaces, physical-mechanical properties, etc.)
  • Assessment determination of deactivating properties of optimal samples in CTOBR. Also the estimation of sanitary- hygienic and toxicological properties of optimum samples in conformity with standard regulating documents will be provided. On the basis of these data at the end of the project the recommendations on application of the developed deactivating coverings will be given (CTOBR).
  • Tests of several optimum samples in real contamination conditions at the Armenian NPP. Gamma-spectrometric analysis to determine surfaces contaminations and its radionuclide composition before and after coverings applying and also set of radionuclides in removed films will be conducted. Analysis will be conducted by using low-background gamma-spectrometer device with GeLi detector and “ASPEKT” programme support.


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