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Barriers Improving Environment Safety

#1247


Development of the Engineered Barriers to Assure the Improvement of Environmental Safety for Objects in the Nuclear Power Industry

Tech Area / Field

  • ENV-WDS/Waste Disposal/Environment

Status
3 Approved without Funding

Registration date
13.04.1998

Leading Institute
All-Russian Research and Designing Institute of Complex Energetic Technology, Russia, St Petersburg

Supporting institutes

  • Khlopin Radium Institute, Russia, St Petersburg\nA.N.Frumkin Institute of Physical Chemistry and Electrochemistry, Russia, Moscow

Collaborators

  • Lawrence Livermore National Laboratory / University of California, USA, CA, Livermore

Project summary

Radioactive waste (RW) is one of the primary sources of radionuclide release into environment. RW are generated at the nuclear fuel cycle facilities, nuclear power plants, and in other branches of national economy. All RW regardless of the characteristics are disposed of in the special equipped repositories, where the waste should be stored for hundreds and in certain cases thousands of years. Taking into account high toxic hazard of RW, the repository structure should assure the immobilization of radionuclides both under normal and under extreme operation conditions.

Currently the multi-barrier concept of protecting environment from the harmful impact of the RW is generally adopted. The concept provides for the creation of an additional engineered barrier within the repository. The engineered barrier may also be created across the radionuclide contaminated water flow for decontamination of the latter. Usually, the well studied and available sorbents are used as the engineered barrier material. However, as a rule, there is no data on the effect of the specific conditions in the RW repositories, namely, thermal and radiation fields, complex macrocomposition of the liquid phase, long period of operation (hundreds of years) on the capability of the sorbent to adsorb and retain radionuclides. Besides, efficiency of the protective barrier is defined not only by the absorbing characteristics of the material used, but also by the radionuclide migration rate within the barrier. Therefore, mathematical modeling of migration processes of the waste components within the barrier makes the integral part of work when designing the environmentally safe RW repository and when liquidating the distribution of contaminated water. Only the data on physicochemical characteristics of the barrier material under the real repository conditions in conjunction with the forecast data on the radionuclide distribution within the barrier may eventually allow to determine optimum size of the barrier assuring the required decontamination factor.

Such a complex approach for the design stage of the environmentally safe repositories based on the fundamental physicochemical studies and on the results of mathematical modeling of processes is proposed for the first time.

Primary goal of the proposed Project is the development of the engineered barriers including selection of the material, barrier size and mode of operation to minimize environmental hazards of the nuclear power industry objects from the standpoint of radionuclide release into environment.

In the course of performance under the Project the work will be focused on both physicochemical aspects, associated with the evaluation of the limiting conditions of operation for known sorbents, with the directed synthesis of new sorbents with preset properties, etc., and on the creation of mathematical models for radionuclide migration within the barrier under the conditions as close to actual ones as possible. Proposed complex approach to the solution of the issue of the engineered barrier creation will allow to justify the selection of materials for the barrier composition and modes of operation, as well as to optimize the necessary barrier size.

Primary areas of work under the Project are the following:


· complex assessment of the radionuclide contamination source objects which should be isolated from the environment. Justification of the requirements imposed on the engineered barriers and forecasting of the possible emergency situations with the release of RW outside the repository limits;
· analysis of the data available on the physicochemical properties of natural and synthetic materials with regard to the possibility of the application thereof in the engineered barriers;
· evaluation of the efficiency of application for various natural sorbent classes;
· purposeful synthesis of inorganic sorbents and selection of organic material possessing the selectivity towards radionuclides;
· creation of mathematical models for migration of radionuclides in the engineered barriers and computer studies on the selection of the most effective and efficient protective material compositions;
· development of the recommendations and proposals on the creation of the engineered barriers for RW repositories and burial sites, for reservoir conservation, and for decontamination of the contaminated surface (underground) water.

Implementation of the Project as a whole will allow to provide the employees of the radiochemical facilities, NPPs, and other objects of nuclear power industry with the practical manual on the creation of the engineered barriers with preset properties and with the necessary data on the composition of barrier composites based upon the inexpensive natural materials and waste processing products.

Proposed concept for the approach to the solution of the issue of improving environmental safety of the objects in nuclear power industry will be based upon the fundamental research of the radionuclide immobilization mechanisms by various sorbents under the conditions specific for the objects in nuclear power industry as well as on the techniques for production of inexpensive direct action sorbents.Optimization of the protective properties of the engineered barriers will be conducted with the aid of computer modeling od radionuclide migration processes. Expected results are to be of interest for all countries having nuclear power plants and, as such, considerable radioactive waste quantities located on their territories (Great Britain, Germany, Russia, USA, France, Japan, and others).

Developed mathematical models and the database on sorption characteristics of various natural and artificial materials may be also successfully used in chemical industry for protection of natural objects.


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