A general view of the unfinished Olkiluoto-3 nuclear reactor in Eurajoki, Finland August 17, 2017. REUTERS/Lefteris Karagiannopoulos

Investigation is still ongoing of cracks recently discovered in feedwater pumps at Finland's Olkiluoto 3 (OL3) nuclear reactor, making it impossible to set a date for resumption of test production, operator Teollisuuden Voima (TVO) said on Monday.