INES-event
INES 1

MALFUNCTION IN THE SYSTEM OF NEUTRON CONTROL OF REACTOR POWER FOLLOWING THE REPLACEMENT OF A CONTROL ROD SWITCH

On July 11, 1994, Unit 2 was under normal operation at a thermal power of 2100 MW, when one of the two control rod switches was replaced in order to correct a small malfunction. After the replacement the switch was tested. In the neutral position the local automatic control rod selected for test performance failed to function (it was lifted upwards by 0.5m). The switch was replacedby a new one and tested again. This time the test was successful. It later emerged that interconnection in the first switch was not made to design.
The investigation of the cause of the malfunction revealed safety culture deficiencies.

Justification: Basic level of rating: 0 (Table II - A1). Final rating level 1.

Location: IGNALINA-2
Event date: Mon, 11-07-1994
Nuclear event report
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