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High-Temperature Fuel Elements


Investigation of Promising Fuel Materials for PWR Having Maneuverable Operating Conditions.

Tech Area / Field

  • FIR-FUE/Reactor Fuels and Fuel Engineering/Fission Reactors

3 Approved without Funding

Registration date

Leading Institute
NPO Lutch, Russia, Moscow reg., Podolsk

Supporting institutes

  • Kurchatov Research Center, Russia, Moscow

Project summary

The main problem of developing fuel elements for space and terrestrial reactors consists in cladding deformation due to fuel swelling during long-term service-life. In addition, the cladding acquires deformation of non-radiative nature under conditions of changing fuel element power because of thermal ratchet - and pawl mechanism. The stated power changes are planned for the reactory having manoeuvre operating conditions and accompany developing fuel elements during their tests as parts of research reactory.

Solution of the problem of increasing geometric fuel element stability by raising cladding thickness and free space in the ca-vity of fuel element isn't optimal as this results in unacceptable impairment of mass-dimensional reactor characteristics and decrea-se of its economic performances. That's why investigations into developing "plastic" ("soft") fuel materials providing cladding stress and deformation reduction and constant mass-dimensional reactor characteristics are pursued in Russia and other countries.

The conception of "soft" fuel materials is being developed conformably to thermionic reactory, in the RI of SIA "Lutch" since the seventies. In the frames of this conception the following fuel compositions have been developed:

- uranium dioxide having porosity which is not influenced by thermal and radiative sintering;

- uranium dioxide alloyed by rareOearth element oxides.

By the present time methods of producing these fuel materials have been developed, and the first results which confirm the ad-vantages of the developed fuel compositions have been obtained. In particular, it was shown that uranium dioxide having stabilized porosity (10-15%) exhibited an optimal property combination at operating parameters of a thermionic fuel element, i.e., its creep rate exceeded the rate of conventionally dense uranium dioxide by a factor of 3-10, and the sweeling rate decreased by a factor of 2-3 at the same time.

The goal of this project is:

- a comprehensive investigation into the properties of the fuel compositions developed in the RI of SIA "Lutch";

- comparative out-of-pile tests of model fuel elements having these fuel materials under heat cycling conditions;

- analysis of possibility of using the developed fuel materi-als in terrestrial industrial reactors.


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