Stichting Laka

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, 21-08-1997
ERF description: On 20 August 1997 at 02:30 tests of the modified turbine controller were being carried out and for this reason three out of six main coolant pumps were switched off. Reloading of the reactor and the turbines occurred as expected. At 02:33 unexpedcted level increase in one of the six steam generators (SG) was observed. The level increase continued though the level interlock actuated properly and operator action was carried out. At 02:37 unit protection on high SG level actuated that caused the trip of both operating turbines and consequently reactor protection actuated. During the reactor protection actuation sticking of one of the 37 control rods was identified in a position about 200-250 cm (25-50 cm from the upper end position). The parameters of the reactor were stabilized. The cause of the SG level increase has not yet been identified. For defining the causes of the control rod sticking elaboration of a programme was started. Cooling down of the reactor was initiated.
On 7 August 1997 sticking of the same control rod was identified during starting the reactor after annual outage. That time the sticking was eliminated with repeated operation of the rod. During additional tests of the affected rod the failure did not reoccur, the reactor was restarted.
INES rating:
Table II (chapter III-2.4.2) was used since initating event occurred (trip of both operating turbines). The frequency of the initiating event is expect (column 1 of the table). The reactor protection system is able to fulfill its safety function in case of sticking of one control rod, requirements set by the Technical Specifications were fulfilled. Therefore row B of the table was used and the basic rating 1/2 was selected. Additional uprating factor was taken into account according to chapter III-5.3. of the INES manual, namely the repetition of the event indicated that the possible lessons have not been learnt. The final rating was selected level 2.
ERF rating date: 20-08-1997
ERF contact person: Mr. G. Macsuga
ERF address: Hungary
ERF affiliation: Hungarian Atomic Energy Commission, Nuclear Safety Inspectorate, P.O. Box 565

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