12 Dec (NucNet): 12 Dec (NucNet): France’s nuclear regulator ASN has asked state-controlled nuclear operator EDF to strengthen technical controls at the four-unit Cruas nuclear station following a series of “significant events” in controlling the nuclear chain reaction in both double-units in the second half of 2016. ASN said there were errors in setting certain parameters for the automatic control system and that the staff did not sufficiently understand what they did. No event on its own was serious, but the repetition and occurrence of incidents in all four units was a problem, ASN said. ASN did not give technical details of the events, but said it had asked EDF for root cause analyses and a comprehensive package of measures to prevent them happening again. The Cruas nuclear station, near the town of Montélimar in southern France, has four pressurised water reactor units that began commercial operation between April 1984 and April 1985.