Radiation damage calculations of composite materials

01.01.2008 - 31.12.2009
Research funding project
Basic features of radiation damage: The radiation load of the first wall of fusion systems is a major problem for the realization of commercial fusion units. Fast neutrons (14 MeV) and ¿Ñ-particles (3.5 MeV) are the main contributors to this load but some transmutation products are important as well. The transmutation products such as H (n, p); (n, d); (n, t) and He (n, ), which have significant an effect on the microstructural stability of the first wall materials, are the consequence characteristic of the high energetic neutron produced in the fusion reactor. The number of atom displacements (dpa) can be calculated by the Norgett-Robinson-Torrens relation [A], where the following relation can be extracted. A general wall load (in MW/m2) is related to the fast neutron flux and causes 1 MW/m2 4.1013 n/cm2s 3.10-7 dpa/s, which gives 1 MWa/m2 ¿° 10 dpa. These values vary only little between metallic and non-metallic (e.g. SiCf/SiC) materials but the He- and H-production are considerably larger for non-metallic materials. Main advantages for using SiCf/SiC composites as first wall material in the fusion reactor are high-temperature operation, corrosion resistance and extremely low induced radioactivity. Whereas for various steels the radiation damage has been studied in detail such investigations are rare for SiCf/SiC [B1-B5]. SiCf/SiC permits higher temperatures and lower activation but shows problems concerning ductility and a different radiation handling of fibers and matrix [D1,D2]. The advanced Monte-Carlo program for radiation damage calculations (MCNP5 and MCNP5 1.4 MCNPX 2.5) will be adapted to a porous ceramic matrix composite such as SiCf/SiC composites and other candidate materials. A neutron flux spectrum in the first wall materials for selected data library (ENDF/B-V, ENDF/B-VI and CLAW-IV) will be employed in order to evaluate the displacement per atom values which are taken place the neutron interaction with the first wall material [C3, C6]. In calculating the displacement cross section for the structural material two steps are involved. First, the differential primary knock-on-atom production cross section is determined as a function of neutron energy and knock-on-atom energy. A secondary defect production function is then used with knock-on-atom production cross section to define a neutron energy dependent displacement cross section [D6]. The source of the Monte Carlo Code MCNP5 has been provided to the Atominstitut through the Nuclear Energy Agency (NEA) based in Paris and has been inspected to be adapted to this project The method itself is familiar to the TU Wien, Atominstitut, as they were developing Monte Carlo codes in parallel to the LANL in the early 1970th on the same theoretical basis and with similar tools [D3-D5]. The MCNP5 code treats an arbitrary three dimensional configuration of materials in geometric cells bounded by first and second degree surfaces and fourth degree elliptical tori. Pointwise cross section data are used. For neutrons, all reactions given in a particular cross section evaluation (such as ENDF/B VI) are accounted for. Important standard features that make MCNP very versatile and easy to use include a powerful general source, criticality source, and surface source; and a rich collection of variance reduction techniques; a flexible tally structure; and an extensive collection of cross section data.

People

Project leader

Institute

Grant funds

  • European Commission (EU) FP7 EURATOM 7.Rahmenprogramm für Forschung European Commission - Framework Programme European Commission Application number ET2-A-2008-193

Research focus

  • Metallic Materials: 25%
  • Non-metallic Materials: 15%
  • Composite Materials: 40%
  • Materials Characterization: 20%

Keywords

GermanEnglish
Strahlenschadenradiation damage
Wandmaterialien in Fusionsreaktorenwall material in the fusion reactor

Publications