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Influence of long-term aqueous leaching of irradiated graphite on surface properties and behavior of radionuclides

Published online by Cambridge University Press:  24 January 2020

Andrey A. Shiryaev ,
Anna G. Volkova ,
Stanislav Dvoryak ,
Maximillian S. Nickolsky  and
Elena V. Zakharova
Andrey A. Shiryaev*
Affiliation:
Institute of physical chemistry and electrochemistry RAS, Leninsky pr. 31, korp. 4, 119071, Moscow, Russia (shiryaev@phyche.ac.ru) Department of Chemistry, Lomonosov Moscow State University, Leninskie gory, 1 bld.3, Moscow, 119991, Russia Institute of geology of ore deposits, petrography, mineralogy and geochemistry RAS, Staromonetny per. 35, 119017, Moscow, Russia
Anna G. Volkova
Affiliation:
Institute of physical chemistry and electrochemistry RAS, Leninsky pr. 31, korp. 4, 119071, Moscow, Russia (shiryaev@phyche.ac.ru)
Stanislav Dvoryak
Affiliation:
Department of Chemistry, Lomonosov Moscow State University, Leninskie gory, 1 bld.3, Moscow, 119991, Russia
Maximillian S. Nickolsky
Affiliation:
Institute of physical chemistry and electrochemistry RAS, Leninsky pr. 31, korp. 4, 119071, Moscow, Russia (shiryaev@phyche.ac.ru) Institute of geology of ore deposits, petrography, mineralogy and geochemistry RAS, Staromonetny per. 35, 119017, Moscow, Russia
Elena V. Zakharova
Affiliation:
Institute of physical chemistry and electrochemistry RAS, Leninsky pr. 31, korp. 4, 119071, Moscow, Russia (shiryaev@phyche.ac.ru)
*
*(Email: a_shiryaev@mail.ru)
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Abstract

Samples of real irradiated (i-)graphite from bushings of RBMK reactor after several types of decontamination treatments were put in contact with aqueous solutions modelling underground water of Nizhnekansky massif (Russia) equilibrated with bentonite for periods up to 1.5 years. Leach rates of radionuclides and evolution of graphite surface morphology and oxidation state were monitored using nuclear spectroscopy, SEM and XPS. After the experiment, less than one third of surface carbons remains unoxidised. Extensive precipitation of secondary phases (alumosilicates, carbonates) was observed on some samples and is possibly correlated with surface oxidation extent. The leach rates of dose-forming 14C and 36Cl are comparable with the leach rates of radionuclides in glassy waste forms. According to the current study i-graphite could be regarded as a waste form, which is suitable for near-surface disposal.

Keywords

waste management
Type
Articles
Information
MRS Advances , Volume 5 , Issue 3-4: Scientific Basis for Nuclear Waste Management XLIII , 2020 , pp. 177 - 184
Copyright
Copyright © Materials Research Society 2020

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References

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