Fall of a steam generator in the Paluel reactor 2 building: ASN has called for an immediate inspection
On 31st March 2016, EDF informed ASN of a fall by a steam generator during handling in the Paluel reactor 2 building.
Reactor 2 has been shut down since May 2015 for the third ten-yearly in-service inspection. These wide-ranging maintenance operations include replacement of the four steam generators1 on the reactor’s main primary system. The operations involved in removal of a used steam generator from the reactor building include a handling phase: the equipment is placed on a trolley enabling it to be extracted from the reactor building. During this operation, it is tilted from its original vertical position to a horizontal position.
On 31st March 2016, reactor 2 was shut down, the nuclear fuel was completely unloaded from the vessel and stored in the spent fuel pool in the fuel building. The reactor cavity was empty and covered with protective plates. A used steam generator was being handled prior to removal, in the almost vertical position, with its bottom end resting on chocks on the removal trolley and its top being supported by a system of slings attached to a handling beam, itself connected to handling machinery mounted on the reactor building’s polar crane. The steam generator tipped over completely and fell onto the ground, partly on the concrete of the reactor building and partly on the reactor cavity protection plates, some of which were damaged. The handling lifting beam also fell.
EDF immediately evacuated the reactor building. One worker was slightly injured, while two others were suffering from shock. The medical services took charge of them. The results of the radiation protection checks carried out by EDF on the workers proved to be normal. The safety of the installation remained unimpaired.
Inspectors from the ASN Caen division, who reached the site at about 17h30, carried out a reactor inspection from the nuclear safety and labour inspectorate viewpoints. The follow-up letter to this inspection is currently being drafted and will be posted on the ASN website. ASN is continuing its monitoring actions.
1. The steam generators are components 22m high and weighing 465 tonnes each. These components are designed to transfer heat between the water in the primary system (which is heated by the nuclear reaction and circulates through small diameter metal tubes) and the water in the secondary system, in order to produce the steam used by the turbine to generate electricity