CBRN event in Hungary on Mon 4th May 2009

During refuelling outage on 04/05/2009, Self Powered Neutron Detector (SPND) was transported from the reactor into the high activity waste storage pit according to a work program. During transfer, the (wire rope) cable holding the grab, which moves inside the SPND chain remover tube-shaped container, broke when the crane was moving laterally. The detector and its grab fell down onto the working area covered with protective clingfilm through the transfer path. Due to falling the 4 m long detector tube became bent and tilted onto the decontamination tank of control rods drivers. No damage of other equipment occurred. The event resulted in increased radiation in the reactor hall. All activities in the reactor hall were suspended, personnel were evacuated and the reactor hall was reclassified to non-accessible area. The workers in the reactor hall were not exposed to radiation over the daily screening level. The dose rate measured at 1 meter from the SPND tube exceeded 50 mSv/h. The area was secured, i.e. cordoned off and warning signs were posted. After the event a special maintenance meeting was summoned and the steps of emergency operation were determined.