The plant was switched off last week after power lines from the facility to the Croatian capital stopped transmitting.
However, the plant is installing a diesel powered generator, which will be operational next year, to minimize the risk of damage from an earthquake.
The plant, built by Westinghouse and owned jointly by Slovenia and Croatia, is situated about 30km west of Zagreb, Croatia.
The plant also plans to strengthen levies along the river Sava to reduce the risk of flooding.
A total of EUR30m ($42m) has been invested in the facility to update security systems to minimize an accident risk in future, Bloomberg reported.
