INES-event
INES 2

IMPACT ON SAFETY DUE TO PARTIAL INOPERABILITY OF THE LONG TERM COOLING SYSTEM (WATER SUMP FILTERS)

Anomaly detected by an inspector of the regulatory body. Filters of the water sump on the containment building were not properly installed to prevent safety pumps from sucking debris. This system is expected to inject cooling water to the reactor core after a major rupture of primary piping.
Inspectors of the SCSIN recently found, at Paluel and at Golfech, an anomaly affecting the installation of filtration grids in a circuit belonging to a safety system designed to operate in accident situations. Following investigations, Electricite de France confirmed on 26 September that this anomaly concerns the 1300 MW(e) reactors.
If one makes the hypothetical assumption of a serious leak in the primary circuit of one of these reactors, core cooling water is obtained in the first instance from storage reservoirs provided for the purpose. Subsequently, the water lost through the leak is recovered and collected in a sump on the lower part of the reactor building for reinjection into the core to sustain cooling. This operation requires the use of a circuit equipped from the primary circuit from disturbing the functioning of the reinjection circuit. In a scenario of this type the existence of abnormal orifices in the filters could lead to malfunctioning of the circuit.
All the 1300 MW(e) reactors are at present being brought into line with accepted standards.

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Location: PALUEL-1
Event date: Mon, 01-10-1990
Nuclear event report
Legenda & explanation