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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, 29-11-1993
ERF description: Krsko NPP was in full power operation, approaching end of the fuel cycle, with boron concentration of 127 ppm. At 8:27 a.m. during testing of loop 1 main steam isolation valve bypass valve, local operator erroneously closed main steam isolation valve instead of its bypass valve isolating steam generator no. 1. The resulting increase of flow through steam generator no. 2 caused its pressure to drop to 42 bar that initiated safety injection and consequently reactor trip. The plant was stabilized according to procedures at mode 3 - hot standby with boron concentration of 444 ppm.
During the transient all safety systems were fully available, exept for diesel generator no. 2 which during its start on safety injection signal has not reached the prescribed frequency and was declared inoperable but within operational limits and conditions. After correcting the problem, steam generator was in accordance with the Technical Specifications.
Basis for Rating:
There was no on-site or off-site impact. Table II of the Manual. Initiator: real (expected) - reactor trip, safety function available within operational limits and conditions = 1/2 rating of 1 was chosen as appropriate since the last operability test of the diesel generator no. 2 was successful and no procedural deficiency was discovered.
ERF rating date: 26-11-1993
ERF contact person: Mr. M.F. Levstek
ERF address: Vojkova 59, 1113 LJUBLJANA, Slovenia
ERF affiliation: Slovenian Nuclear Safety Administration

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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