Personnel overexposure while extracting leaky fuel assembly from the reactor core on 21.11.95 at Kursk NPP, Unit 4 (the Russian Federation)

Brief description of the event: The unit was operating at nominal power. Based on Burst Can Detection System (BCDS) indications personnel observed increased activity of steam at the fuel channel (FC) outlet which indicated leaky fuel rods. Once the affected FC with depressurized fuel rods was identified, efforts were started to discharge the affected fuel assembly from the 47-45 FC. During fuel assembly discharge operation radiation monitoring system alarms went off periodically in the central (reactor) hall. Examination of the place of work performing revealed the following: one fragment of the fuel of 5 mm size was discovered on the receiving unit of the shipping cask with discharged fuel assembly and two fragments of 1.5-2.0 mm size were found on the fuel assembly plug. Fuel fragments were removed in accordance with established procedures. The checking of personal dosimeters of eight workers who took part in the work showed that two persons had increased external exposure doses exceeding the annual limit (58.3 and 56.7 mSv respectively). 2 figs