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Level two incident at Dutch N-plant

Nuclear Monitor Issue: 

(December 13, 1996) An incident at the Borssele nuclear power plant in the Netherlands has been provisionally classified as level two on the IAEA International Nuclear Event Scale (INES). Strangely enough, the Dutch press didn't pay any attention to it.

(463.4606) WISE-Amsterdam -A statement issued by the plant said that an unfiltered venting line -- used to depressurize the reactor containment by controlled release of air to the environment via a ventilation tower -- was found to be open to the atmosphere despite the fact that all four block valves in the line registered closed. The statement said the valves had apparently been mispositioned nine months ago, probably as a result of maintenance work.

The fault, which was discovered on November 21, was corrected within two hours. There was no release of radioactivity either on or off site. However, the event has been rated as level two on the INES scale of one to seven, on the basis of degradation of defense in depth.

The reactor containment is the last line of defense against radioactive releases to the environment; if an event had occurred which could result in radioactivity being released within the containment, that line of defense would have been lacking.


  • INES
  • Dutch Nuclear Safety Authority (KFD)
  • NucNet 25 November 1996

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