Assessment of the Safety Case for the Reactor Pressure Vessel of the Beznau Unit 1 Nuclear Power Plant

The IRP considers that the Axpo Safety Case is acceptable. This is based on the following:

  • It has been established beyond all reasonable doubt that the flaws are laminar ‘agglomerates’ of alumina inclusions, formed during manufacture of the affected RPV shells, and which neither formed nor grew during service.
  • It has been adequately demonstrated that such agglomerates do not significantly affect the materials properties relevant for structural integrity assessment or sensitivity to irradiation damage.
  • The ultrasonic testing carried out on the RPV was sufficient to ensure that all flaws that might significantly affect structural integrity were detected and conservatively assessed.
  • A fracture mechanics assessment of the flaws, using highly conservative assumptions, demonstrated that the case is robust.


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