Fast Reactors and Accelerator Driven Systems Knowledge Base

Conference Article: Neutron damage of some refractory, corrosion resistant candidate materials

J.M. Perlado, E. Alonso, R. Fernandez, J. Garcia, J.M. Martinez-Val, E. Minguez, C. Rubbia, J.A. Rubio

Abstract

The use of some corrosion resistant materials to molten lead, such as refractory materials (W or W-alloys) or other similar materials as a component in Accelerator Driven subcritical Systems (ADS) such as Energy Amplifier (EA) [ 1], under very energetic and intense neutron fluxes, imposes the requirement to carefully study the radiation damage of these materials. A revision of the existing data [2] indicates that Tungsten and its alloys can become brittle at the expected working temperature range. An important effect should be the easy manufacturing and implantation of the adequate design, which could lead to the choice of an specific material (i.e.W, MO,...). Without mechanical loads and reduced thermal stress, the question remains about other potential failures (no tensile/compression) in Tungsten components used as protection, such as bending or impact fracture by internal vibration. Additional assessment via Charpy and other impact and bending type of analysis should be carried out to ensure the validity of the solution. An additional problem could be the impurities generated by transmutation which could affect the microstructure and the activation of W. An alternative to W is the use of Vanadium alloys, which behave also well in liquid metals corrosion environment, although not as well as Tungsten, and seem to have better behavior under irradiation (damage and activation) [2]. The use of ceramic materials, or composites based in Sic, needs also to be reviewed as an alternative. For basic understanding of microscopic effects [3], high-energy cascades have been simulated in high-Z materials using molecular dynamics with a modified embedded atom method potential, and MonteCarlo diffusion of defects. The results show that both vacancy and interstitital clusters form with high probability as a result of intracascade processes. The formation of clusters has been interpreted in terms of the high pressures generated in the core of the cascade during the early stages. There is some evidence that correlation between interstitial and vacancy clustering exists.

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key words: Fast Neutron Spectrum Systems, Nuclear Technology
Reference:
Technical Committee Meeting, Madrid, Spain 17-19 September 1997
International Atomic Energy Agency, Vienna (Austria)
IAEA-TC--903.3, pp:649-657