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Fullerene-containing Carbon Matrices for Transmutation of Iodine

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Synthesis and Investigation of Fullerene-Containing Carbon Matrices for Transmutation of Iodine-129

Tech Area / Field

  • ENV-RWT/Radioactive Waste Treatment/Environment
  • ENV-WDS/Waste Disposal/Environment
  • MAT-CER/Ceramics/Materials

Статус
3 Approved without Funding

Дата регистрации
11.07.2006

Ведущий институт
Khlopin Radium Institute, Russia, St Petersburg

Соавторы

  • Battelle Energy Alliance LLC (BEA) / Idaho National Laboratory, USA, ID, Idaho Falls\nUniversity of Sheffield / Department of Engineering Materials / Immobilisation Science Laboratory, UK, Shiffield

Краткое описание проекта

Main goal of the Project is investigation of iodine-129 (129I) transmutation process using fullerene-containing carbon material (FCC) simultaneously as iodine host-matrix and transmutation target. Samples of FCC doped with different amount of iodine: initial ones, as well as irradiated by neutrons in research nuclear reactor WWR-M will be studied. An additional goal of the Project is calculation of optimal conditions of 129I transmutation and evaluation of its economical sensibility for existing types of nuclear reactors.

Iodine-129 (129I) is dangerous long-live radionuclide (with half-life1.54 x 107 years), which is formed and accumulated in matrix of spent nuclear fuel as a result of uranium decay. The unique chemical feat ures of iodine such as high volatility and the absence of durable compounds cause its high migration ability. Radioactivity of 129I increases additionally its chemical mobility. There are no so far ecologically acceptable methods of 129I immobilization. Some countries (France, UK) discharge 129I into the sea after reprocessing of spent nuclear fuel. In USA, Canada, Sweden and Russia there is huge amount of 129I connected with spent fuel under temporary storage. Some amount of 129I after reprocessing of spent fuel was converted into forms of temporary storage, for instance, CuI (Russia) or Ag-doped zealots (Japan). However, there is still no durable host-matrix of 129I which might be acceptable for final disposal. A prospective carbon material FCC has been recently developed at Laboratory of Applied Mineralogy and Radiogeochemistry of the V. G. Khlopin Radium Institute. It can be used not only for iodine absorption but also as a host matrix of transmutation target, which then becomes a final waste form after 129I transmutation. This material is synthesized in electric arc in inert atmosphere using special original equipment developed and fabricated at
V. G. Khlopin Radium Institute. Initial fullerene-containing carbon material (FCC) is dispersed powder, which consists of mainly non-crystalline (amorphous) carbon. Amount of fullerene admixtures (mainly C
60 and C70) depends on synthesis conditions and varies from 1-2 to 8-9 wt.%. The FCC might be granulated or pressed into pellets and used as an absorbent like well-known activated carbon. However, main advantage of FCC in comparison with other absorbents is its ability to keep absorbed iodine during physical-chemical conversion of FCC into other forms, for instance, during hot pressing. It is proposed that iodine-doped FCC might be converted into more chemically and mechanically durable material like SixCy or CxNy avoiding releases and loss of iodine. An additional advantage of FCC, which, however, requires further investigation, is its “transparency” for xenon forming as a decay product during 129I transmutation. This feature of FCC allows avoiding essential absorbency of neutrons in FCC matrix and matrix swelling under irradiation (as a result, destruction of nuclear fuel rods). In general, initial FCC is not characterized by essential neutron absorbency that allows using FCC as transmutation target. In the framework of ISTC Project the principal features of FCC under various conditions of neutron fluxes will be studied in details. The results obtained will be used for calculation of optimal conditions of 129I transmutation and evaluation of economical sensibility of iodine transmutation at modern nuclear reactors.

Project will be carried out by highly qualified experts of V. G. Khlopin Radium Institutes, who develop and study durable host-matrices for the final disposal of highly radioactive wastes. Most of these scientists were involved in development of technology on purification and extraction of weapons plutonium.


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