Euradwaste '08 - EU Bookshop - Europa

Development of the Methods for Immobilization of Long-lived
Radioactive Waste in Carbon Matrices for Storage and Transmutation
Murat Abdulakhatov 1 , Sergey Bartenev 1 , Mikhail Goikhman 2 , Alexander Gribanov 2 , Valery
Guselnikov 3 , Nikolai Firsin 1 , John Krasznai 4 , Yuri Novikov 3 , Yuri Sazanov 2 , Mikhail Zykov 1
1 V.G. Khlopin Radium Institute (KRI), Saint-Petersburg, Russia
2 Institute of Macromolecular Compounds (IMC), Saint-Petersburg, Russia
3 Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia
4 Kinectrics Inc., Toronto, Canada
Summary
Conditions for immobilization of long-lived radioactive waste in carbon matrices were investigated.
Stable isotopes of rhenium, iodine and europium were used as chemical analogues of
low-lived radionucledes: 99 Tc, 129 I and 241 Am, respectively. It is shown that the carbon matrices
incorporating the above elements can be produced by carbonization of composites with
ITA-31 polyimide binder, chemical analogues of investigated radionuclides and carbon fabric
as reinforcing component. The elements under investigation were used both in the form of
salts or oxides and in the form of their complexes with ion-exchange resins. The produced
composites were carbonized in inert gas (argon) or in vacuum. The physical-chemical properties
of the samples were studied. It was revealed that the resultant matrices meet the requirements
imposed on waste storage, disposal and transmutation.
1. Introduction
Further development of nuclear power over the world depends to a great extent on solving two main
problems: safety of nuclear power and industrial facilities as well as ecologically reliable and economic
disposal of radioactive waste (RAW) containing long-lived alpha-, beta- and gamma radionuclides.
Hence, the long-term isolation of RAW from biosphere is an important problem responsible
for further development of nuclear power. Of prime attention is the question on management
of long-lived radionuclides because of their serious hazard if they escape into the environment.
The point is that the radioactivity of fission products ( 99 Tc, 129 I) and minor actinides such as
237 241
Np and Am remains practically at the same level over a period of thousand hundreds years.
Two variants are best suited to handle these long-lived radionuclides. One of them consists in
elaborating a method for immobilization of radionuclides into matrices of high thermal, chemical
and radiation resistance for subsequent long-term storage or final disposal [1]. Another variant is
transmutation of long-lived radionuclides into short-lived or stable isotopes in special nuclear reactors
or Accelerator Driven Systems (ADS) [2-3]. It should be emphasized that the both variants involve
production of matrices possessing some properties suitable for prolonged storage or disposal
and transmutation of long-lived radionuclides. The different research centres carry out research on
the development of new techniques for production of reliable matrices. One of such techniques consists
in production of carbon matrices. Carbon matrices can be obtained by carbonization of organic
substances. To meet the requirements placed on the properties of carbon matrices being obtained,
some composites on the basis of polyimide binder ITA-31 were developed [4]. By producing the
carbon matrices it is extremely important to bind nuclides being immobilized by ion-exchange resins
(IER) and complexing agents, which may be used then as components in synthesis of polymer
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