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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: Thu, 18-03-1993
ERF description: Ontario Hydro has reduced power at Bruce Nuclear Power Development to 60% full power as a result of analysis of very low probability accidents being studied as part of a solution to pressure tube fretting. The analysis identified potential for an increase in reactivity from the sudden relocation of the fuel string due to reverse hydraulic loading during a large reactor inlet header rupture. The power reduction provides a significant margin of conservatism to compensate for the maximum accepted reactivity increase for this scenario.
There is no safety concern with normal operation of the Bruce Reactors, however, in the unlikely event of a major loss of coolant, the consequences could be greater than previously assessed. Ontario Hydro is conducting more detailed analysis to determine what actions are necessary to ensure safe operation of the stations at full power.
Five of the units at Bruce were immediately affected by this derating, the remaining three are out of service for maintenance. Operation of the units at Pickering and Darlington is not affected by this analysis.
Using table I, a severity rating of INES=1 was assigned, based on the criterion of Degradation of Defence in Depth, for the unlikely occurrence of a Major Loss of Coolant Initiator, with safety function availability assessed as adequate.
ERF rating date: 17-03-1993
ERF contact person: Mr. W. Andersen
ERF address: 700 University Avenue, Canada
ERF affiliation: Ontario Hydro H11-B1, Nuclear Technology Services Division

This map shows a selection of reports from nuclear and radiological incidents stored in the IAEA NEWS-database.
Locations are estimates. Contact us if a location is wrong.
The map shows a maximum of 100 incidents. If hundred incidents or more are within the map, the yellow perimeter indicates from where events are excluded. Drag or zoom the map to explore different areas.

Power Reactor Research Reactor Radwaste Facility Enrichment Facility Radiation Source Irradiation/Accelerator Facility Transportation

Fuel Fabrication Fuel Reprocessing Research Facility Mining/Milling Radioisotope Processing/Handling Facility Other