LONDON, April 18 (Reuters) -
* Royal Dutch Shell said its Moerdijk petrochemical plant intheNetherlands was shutting down, but a planned maintenanceturnaround at the site was not yet confirmed
* Workers have been on strike at the Moerdijk plant and thenearby404,000 barrel per day Pernis oil refinery, Europe's largest,since April 8
* A spokeswoman for the oil major said Shell was "carefullyoptimistic" at this point about the lower olefins unit shuttingdown "which will hopefully lead to the turnaround at some pointsoon"
* She added the turnaround was planned to start at somepointbetween mid April and mid May
* Traders had previously expected the turnaround to takeplacebetween April 16 and June 21(Reporting by Ahmad Ghaddar, Shadia Nasralla; Editing by MarkPotter)