During annual scheduled repairs Tuesday at Unit 5 of the Kozloduy N-plant an increased concentration of radioactive noble gases was detected in the unit's sealed area, the N-plant said Wednesday The increased levels were found to be the result of a heightened concentration of xenon gas (Xe-133).
All working operations were suspended and workers were evacuated from the area. Measures to bring down radiation levels were taken. The gamma radiation in the sealed area reached 10 per cent of the control level.