Zircalloy

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With zircaloy , even zircaloy , Zircalloy or Zircaloy are metal alloys which contain more than 90% of zirconium consist, respectively. Because of its corrosion resistance, zirconium is of great importance in chemical apparatus engineering (nozzles, pump parts, pipes or valves). The alloy also contains small amounts of tin (approx. 1.5%) and mostly other metals such as iron , chromium , nickel or niobium .

Due to its low capture cross section for thermal neutrons , d. H. Its high neutron permeability (neutron absorption is 30 times lower than that of steel) and other favorable properties, Zircalloy is used for the cladding tubes of the fuel rods of water-cooled nuclear reactors . Its production is due to the complete removal of the raw ore contained in the hafnium to pay attention because this is a strong neutron absorber is.

In order to achieve the best possible heat conduction in the gap between the cladding tube and the nuclear fuel, the helium gas is injected into it.

In the nuclear reactor, Zircalloy surfaces also inevitably suffer from corrosion. The thickness of the oxide layer that forms increases steadily over time, depending on the nature of the material, the cladding tube temperature and the chemical composition of the surrounding cooling water. In addition to radiation damage, corrosion is one of the processes that limit the service life of the fuel elements in a reactor to around three to five years.

Web links

Individual evidence

  1. ↑ Jürgen Gobrecht, Erhard Rumpler, Material Technology - Metals (p. 234 + 235) ( Memento from June 12, 2015 in the Internet Archive )
  2. ^ A b c Franz Joseph Dreyhaupt (Ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , p. 1343.
  3. ↑ A. Ziegler, HJ Allelein (Ed.): Reaktortechnik : Physikalisch-Technischen Basics . 2nd edition, Springer 2013, ISBN 978-3-642-33845-8 , pages 199, 202
  4. ^ Günter Kessler: Sustainable and safe nuclear fission energy. Technology and safety of fast and thermal nuclear reactors . Springer 2012, ISBN 978-3-642-11989-7 , page 77
  5. ↑ books.google.nl, Jan Kopitz, Wolfgang Polifke: Heat transfer: Fundamentals, analytical and numerical methods - Section: Stationary heat conduction (p. 72)