French authorities cleared the restart of nine reactors out of 12 that were caught up in the search for high carbon concentrations in steel components manufactured by Japan Casting and Forging Corporation (JCFC). The search concentrated on steam generator channel heads that were implicated in an on-going investigation of potentially substandard steel used in components installed in operating reactors. High concentrations of carbon, defined as anomalies, create steel that is more brittle than desired. The investigation began with the discovery of anomalies in certain zones of the vessel closure head and the vessel bottom head of the Flamanville European Pressurized Reactor, which is under construction in Normandy, France. That discovery was made public in April 2015 after routine inspections at the Flamanville project discovered the problem. The ensuing reaction lead to a search for other parts manufactured at AREVA NP's Creusot Forge, where it was discovered that there were also irregularities in paperwork that caused another level of concern for Creusot Forge manufactured components. The widening concern also focused on certain JCFC components. Regulators in the United States and France have repeatedly stressed that the anomalies have not compromised safety at any of the operating reactors. The Nuclear Regulatory Commission has produced a list of U.S. reactors with components that were implicated by the controversy. The French nuclear power regulator Autorite de Surete Nucleaire in mid-October 2016 instructed EDF to carry out additional inspections of the steam generator channel heads of certain reactors within three months. That process was done in two steps, including a “generic” report that was prepared in early December. The second step was a case-by-case review of each of the implicated reactors, which was completed for nine of the reactors this week. On 11 January 2017, the ASN said, EDF asked that the inspection deadline for Tricastin NPP Unit 2 be postponed for two weeks. That request was explained by the risks posed to the electricity grid as a result of demand heightened by cold winter weather that is expected next week. ASN considered this request to be acceptable from a safety viewpoint, setting the date for review deadline at 3 February 2017. EDF also asked for a stay on the deadline set for Civaux NPP Unit 1, a 1450 MWe capacity reactor, to the end of March 2017. ASN is currently examining substantiating data provided by EDF on both of the 1450 MWe capacity units (Civaux 1 and 2), which are of necessity on different review tracks. ASN said it will consider these requests and issue statements on them in the near future. For now, the 900 MWe capacity reactors given permission for restarts are Bugey Unit 4, Dampierre Unit 3, Fessenheim Unit 1, Gravelines Units 2 and 4, Saint Laurent B, Unit 1 and Tricastin Units 1, 3 and 4.