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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: Wed, 28-09-1994
ERF description: A power excursion, which resulted in a reactor trip on overpower, occurred at the McMaster Nuclear Reactor (MNR) during a refuelling operation. MNR is a pool type research reactor currently operating at 2 MW. Following replacement of a shim safety rod control assembly, the fuel assemblies were being returned to the core. After loading the 5th fuel assembly, the shim safety rods were withdrawn to check that the reactor was not critical. The rods were then driven to the 85% withdrawn position instead of required 40% (safeguard position). On insertion of the 6th fuel assembly a blue glow was seen and the reactor tripped on overpower. The Log N trip had been bypassed to avoid spurious trips while moving irradiated fuel into position for loading into the core and the bypass had not been turned off. The power transient maximum was estimated to be about 300% full power. MNR is analyzing this incident to establish energy output, fuel temperature etc. and will be monitoring fuel behaviour. Procedures related to refuelling are being reviewed and revised. Rating is INES level 2 from Table II - Degradation of defense in depth, with an high/expected initiator (reactor trip due to reactivity excursion) and just adequate safety function availability (Level 2 rather than 3 was chosen on account of the full containment provision and the smaller hazard potential to the public of the pool type reasearch reactor compared to a power reactor).
ERF rating date: 13-09-1994
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.
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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