France's Autorité de Sûreté Nucléaire (ASN) said on 5 April that it is "immediately" investigating the accidental fall of a used steam generator inside the reactor building unit 2 of the Paluel NPP in northern France. EDF said on 31 March that the incident happened while removing one of four steam generators as part of the ongoing refurbishment works. Paluel 2, a 1,330MWe PWR, has been offline since May 2015 for the third decennial maintenance outage to enable the unit to continue operating for at least another 10 years. Its reactor pressure vessel and reactor fuel pool were empty at the time of the incident. According to ASN, the steam generator was in vertical position before the fall, with its top attached to the polar crane and its bottom to a special trolley on the floor. The steam generator accidentally detached from the handling mechanism at the top and dropped to the concrete floor of the reactor building damaging some of the plates which protected the reactor fuel pool, ASN said. EDF evacuated the reactor building although contamination checks showed "normal" radiation levels. ASN said the results of the investigation will be published on its website. Paluel 2 is one of four units in commercial operation at Paluel. Commercial operation began in December 1985.