The Hanbit No.2 reactor was shut since 30 October 2013 which is located in Yeonggwang county.
The commission also approved replacement cables for three more reactors shut in a safety scandal, Reuters reports.
The three reactors are Shin Kori No.1 and Shin Kori No.2 in the city of Busan and Shin Wolsong No.1 in Gyeongju.
LS Cable & System will provide cables for three reactors, which are expected to restart by end of December 2013, while KHNP will install the cables in place of those from JS Cable.
The three reactors were shut since May 2013.
The commission reported that tests conducted on new control cables are satisfactory and these could be installed in place of cables supplied with fake certificates.
The new cables will also be used in another reactor which is under construction.
"The commission will thoroughly test their operations once the control cables are installed," it said.
One more reactor is shut for regular maintenance and last one is waiting for approval to carry on operating after reaching the end of its original 30-year life span.