LONDON, July 26 (Reuters) -
* Britain's Heysham 1-2 nuclear reactor went offline onFridaymorning in an unplanned outage, operator EDF Energy said.
* The reactor was shut down following an issue with acondensatewater valve on the conventional part of the station, a companyspokesman said.
* The 585 megawatt reactor is estimated to come back onlineonJuly 31.(Reporting by Ekaterina Kravtsova; editing by Nina Chestney)