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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: Fri, 16-07-1993
ERF description: During full power operation, channel B of Reactor Regulating System and channel E of Reactor Protective System were reading less neutron power than other channels. To match with other channels, gain of ion chamber amplifiers of these channels was increased and also manual correction on protective channel E was done. Linear neutron trip set-points from primary shutdown system and secondary shutdown system were decreased. No problem could be found in ion chambers and their associated circuitry. On further investigation during reactor shutdown water was found in ion chamber housing, which caused the low neutron power signal in channel B & E (channel B and Channel E, both ion chambers are in same housing).
Justification: Unplanned bulk increase in reactivity could have been the possible initiator. Since no initiator occurred, Table-1 has been used for rating. The safety function availability was full, so the event rating comes to 0. But due to possibility of common cause failure (water ingress into other ion chambers also) the event has been uprated by 1.
ERF rating date: 03-03-1993
ERF contact person: MR. V. KUMAR
ERF address: BARC, TROMBAY, India
ERF affiliation: GOVERNMENT OF INDIA, ATOMIC ENERGY REGU, OPERATING PLANTS SAFETY DIVISION, CENTRAL COMPLEX, 4TH FLOOR

This map shows a selection of reports from nuclear and radiological incidents stored in the IAEA NEWS-database.
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Fuel Fabrication Fuel Reprocessing Research Facility Mining/Milling Radioisotope Processing/Handling Facility Other