** Shares of Australia's Viva Energy VEA.AX fall as much as 2.4% to A$2.44, biggest intraday pct drop since April 27
** Fuel retailer says it expects repairs necessary to restart a damaged unit at Geelong Refinery will take around six weeks
** Co expects restart in June, after a fire at the largest of Australia's two refineries on April 15 hit petrol production
** Production expected to increase over 90% of capacity following restart of RCCU, co adds
** Day's move trims stock YTD gains to 19%
(Reporting by Aamir Sheik Khalid in Bengaluru)
((Aamir.SheikKhalid@thomsonreuters.com))