Reuters cited Nuclear Security Council as saying that the plant officials have been able to identify the cause of the pressure drop.
The plant, which is jointly owned by Iberdrola, Endesa and Gas Natural, currently remains secure though offline.
The production halt, however, does not have any implications on the safety of the employees or the general public and has been categorised in the International Nuclear Event Scale as Level 0 event.
The nuclear power plant comprises two PWRs of 1049 and 1044 MWe.
