In late 2014, mechanical tests performed in France on a Reactor Pressure Vessel closure head representative of that of the Flamanville EPR revealed the presence of a high carbon concentration in the central top part, leading to lower than expected fracture toughness values.
In addition analyses carried out since 2015 on operating reactors concluded that certain steam generator channel heads, manufactured by Areva Creusot Forge and Japan Casting and Forging Corporation, obviously had areas having high carbon content.
Such events have been shared by ASN and discussed among WENRA Members in order to issue a recommendation. This recommendation is focusing on investigations performed by the licensees and the evaluation of the results by the Regulators, but also on guidance related to manufacturing processes, and finally on WENRA’s support to the work performed on codes and standards.

WENRA Recommendation in connection with macro-segregations

WENRA Recommendation on macro-segregations