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Geocement Binders for Liquid Radioactive Waste

#A-1749


Development of New Geocement Binders Based on Natural Minerals of Armenia and Technology of LRW Conditioning into Ecologically Safe Compounds

Tech Area / Field

  • ENV-RWT/Radioactive Waste Treatment/Environment
  • OBS-NAT/Natural Resources and Earth Sciences/Other Basic Sciences

Status
3 Approved without Funding

Registration date
07.05.2009

Leading Institute
Yerevan State University, Armenia, Yerevan

Supporting institutes

  • FEI (IPPE), Russia, Kaluga reg., Obninsk\nResearch Center For The Problem Of The Non Proliferation Of Weapons Mass Destruction, Armenia, Yerevan

Collaborators

  • Roosevelt University, USA, IL, Chicago\nUniversity of Naples Federico II / Dipartamento di Ingegneria dei Materiali e Della Produzione, Italy, Naples\nEmergencies Science and Technology Division Environment Canada, Canada, ON, Ottawa\nUniversita degli Studi di Milano / Dipartamento di Fisica, Italy, Milan\nInstitute of Nuclear Chemistry and Technology, Poland, Warszawa\nTexas A&M University / College of Engineering, USA, TX, College Station\nStoller Ingenieurtechnik GmbH, Germany, Dresden\nTexas A&M University / Department of Chemistry, USA, TX, College Station

Project summary

The problem of radwaste management and disposition of radioactive wastes (RAW) is extremely topical nowadays; therefore, the work to ensure environmentally-friendly radioactive waste storage facility conditions is critical and cannot be delayed.

For reducing the CRL (concentrated liquid radioactive waste) volume, a treatment of which is associated with significant technical and environmental problems it is expedient, namely, to carry out cleaning from radionuclides the LRW at early stages of their formation. The procedures associated with neutralization of these LRW (liquid radioactive waste) are the subject of the present ISTC project.

Objective of the project:

The development of the low resource- and energy-saving technology for the conditioning of liquid radioactive waste, particularly, by immobilization into geocement compound materials based on readily available and inexpensive natural and technogen radiative-steady materials of Armenia, development of the technical task and selection of the equipment of experimental - pilot installation applicable for the Armenian Nuclear Power Plant (ANPP).

As a feed stock for the formulation of geocement compounds different natural and man-caused radiative steady materials of Armenia (obsidians, perlites, tuffs, lithoide pumices, boron containing travertines, barium sulfates, as well as alkali and earth-alkali magmatic ores such as syenite, phonolite, trachyte, nepheline syenite, etc) may be used.

As associated mineral the absorbents will contain the components of tuff (e.g., clay minerals, feldspars, various SiO2-phases). The clay minerals are additionally very efficient sorbents for 137Cs and 90Sr [1-2].

As experience and analysis of literature sources showed [3-4], the solidification of CLRW having complex chemical composition, high alkalinity, high content of inorganic and organic substances and high radioactivity for the purpose of producing of a water resistant fire-safe and radiation stable compound providing also the reduction of RAW (radioactive waste) at their solidification is a complicated technical problem.

Alternative method.

The method for the treatment of LRW of middle level specific activity with the use of natural absorbents is considered to have closer relation to the proposed technical solution [5].

The disadvantage of this technique is the restriction of the main component of binding system of man-made glassy slag material in a limited quantity.

The subject of studies and investigations of the present project is the conditioning of the LRW, especially, radioactive sorbents, including the structure of zeolites on the basis of the granule of silica-alumina minerals.

The glassy materials proposed in the project will considerably expand the possibilities of application of geocement binding materials.

Huge quantities of low-price volcanic glasses, like perlite, volcanic tuff, obsidian, etc., are common in Armenia and Russia. The wide expansion of volcanic glasses (perlite species), constancy of chemical and mineralogical compositions, the detailed examination of every deposit and the low prime cost allow to examine these volcanic glasses as ready for industrial use as mineral binders [6-13]. Obsidians and other volcanic rocks lose water during the calcination forming an expanded porous material. Perlites, which are rapidly cooled igneous minerals, have amorphous structure. Being fine ground (up to 350 m2 / kg), they show a high chemical activity.

Before the authors of this project is the task of increasing the longevity of the solidified rocks by means of utilization of novel binding materials and result in new inexpensive and radiation stable materials using simple and cost-effective technology and natural minerals as raw materials.

Subject of development

  • Justification of the choice of promising natural minerals and techniques of their treatment for production of reference raw materials building up the geocement binder.
  • Development of formula and technological process parameters of conditioning LRW, particularly, in time of sorbent immobilization into geocement compound.
  • Development of demonstration cementing facility and technology of sorbent conditioning into geocement compound.
  • Study of structure and properties of specimen samples of geocement rock, experimental and theoretical justification of its durability ensuring 137Сs and 90Sr radionuclides isolation from the biosphere over a period of more than 300 years [24].

Novelty of the work

Use of natural minerals as reference raw material of the binder and development of unconventional technologies of mineral treatment and cementing at conditioning LRW and radioactive sorbents into radiative-stable alkaline alumosilicate compounds being distinguished by high waterproofness to natural aqueous media.

As a result of the project implementation a technology will be developed characterized by:

  • A minor energy and material consumption, minor amount of stages,
  • Fire-safety,
  • Excluding the formation of secondary radioactive wastes with additional chemical toxicity; it is based on the use widely available natural and technology-generated materials;
  • It will provide with incorporation of all radionuclides, inorganic and organic substances-components of CLRW into water-resistant isolating compound with enough mechanical durability;
  • A contribution to the resolving ecological problems by means of practical implementation inexpensive conditioning systems with a tangible economic effectiveness.

It is suggested also in the project to consider the issue of combining sorbent conditioning with slime conditioning (silt formations being accumulated in settling tanks) also pertinent to middle-active wastes (MAW) or their separate conditioning.

As a result of project fulfillment a technology for conditioning LRW, particularly radionuclide-saturated sorbents including zeolites for their safe storage or burial. The technology will be developed using inexpensive natural materials of Armenia and industrial stone-like waste as components forming the compounds, into which radioactive sorbents are incorporated. New data on use of natural minerals for the environment protection will be also obtained. These compounds are the first of the four safety barriers biologically isolating important radionuclides from the biosphere.

The introduction of this technology will provide with solution of the above mentioned tasks in the sphere of liquid radioactive wastes, will decrease potential hazard of LRW impacts on the environment.

The proposed work has high likelihood of contributing to the resolution of liquid radioactive waste problems in both nations.

Competence of the project participants

The participants who will work on the project development are the specialists (doctors of sciences, candidates of sciences, scientific employees and engineers) experienced in the last 10-15 years in the field of:

  • development of the methods of purification of LRW from radionuclides by using natural sorbents of Armenia;
  • treatment of RAW;
  • study of aluminosilicate binding materials and other systems for formation of geocement compounds containing analogs of rockforming minerals,
  • immobilization of LRW into different cement compounds,
  • manufacturing of the equipment for mixing of powdered minerals and viscous mediums for cement preparation,
  • study of the properties, composition and structure of minerals and rocks with reference to their application for insulation of radionuclides from environment,
  • study of the mechanical strength, radiation stability, water permeability and chemical properties of solid materials applicable to their use for the isolation of biologically significant radionuclides from biosphere.

Expected results and their application

The result of the activities performed within the framework of the Project is the development of a new technology for conditioning LRW, esp. radioactive natural sorbents (zeolites) and slimes (silt formations being accumulated in settling tanks) also pertinent to MAW (or their separate conditioning), development of technical task and selection of equipment for constructing a pilot test facility to study the technological process parameters of radioactive sorbent cementation applied to the problems of radiation safety upgrading at Armenian NPP. This technology may be applied in the centers of LRW conditioning of other countries.

Meeting ISTC Goals and Objectives

The project completely satisfies the ISTC goals and objectives:

  • The project gives an opportunity to scientists and specialists connected with Armenia and Russian Federation, especially those who possess the knowledge and experience in the sphere of mass destruction and missile systems of delivery for reorientation of their skills in the world activity;
  • It supports basic and applied research, development of technologies with peace objectives, especially in the fields of environment protection, and safety provision in nuclear energy;
  • It contributes to the solution of national and international technical problems that are actual(others, besides the above mentioned);
  • It promotes the transfer to the market economy responsible for civil needs.

Role of foreign collaborators include:
  • Exchange of information during project implementation;
  • Provision of comments to technical reports provided by the project participants;
  • Participation in technical check of activity due to the project;
  • Joint seminars, workshops, meetings, consultations;
  • Verification of results using independent methods and /or equipment;
  • Estimation of the technology developed during the project implementation.


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