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Event Report Forms (ERFs) are filed to the IAEA. Sometimes there are multiple event reports, updating the rating, the event description. Here you only see the latest event report

ERF send date: Mon, 24-10-1994
ERF description: Unit 3 was operated at full power. At 11:35 during routine visual inspection of the reactor cover the steaming of the upper part of the fuel channel tract 41-13 was discovered. At 11:43 the unit was shut down by the operator. The refuelling machine was placed on the channel 41-13. On October 20, while the reactor was being cooled the defect was tested. The butt crack was found 70 mm lower of the weld seam of the joint of the holder and the standpipe (assembly 25). The defects of the weld seams were primarily detected in 1980 when consignment of standpipes was detected to have manufacturing defects. The annual ultrasonic testing of these standpipes was performed but during this checking only seam and 50 mm strip of metal adjoined to seam are being tested. The cause of this defect will be investigated. The rating of this event is classified at level 1 due to defence in depth criteria.
Basis for the rating:
This event is rated due to the degradation of the defence in depth criteria according to the procedure based on initiators and using the guidance for structural defects. In fact, the surveillance programme aiming at the identifying of the standpipe defects in the wall could not discover this defect because it was not located in the testing zone. This defect did not challenge the safety systems. (It was not the real initiator.) The basic rating according to the Table 1 of the INES users manual is 0. The potential consequences of this event could be more serious so this event was uprated to 1.
ERF rating date: 24-10-1994
ERF contact person: V. Grishenko
ERF address: KIEV, Ukraine
ERF affiliation: SCIENT. TECHN. DEPT., UKRAINIAN STATE COMM., OBSERVATORNA STR. 11/1

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