By Meeyoung Cho     SEOUL, July 15 (Reuters) - South Korea's nuclear regulator said on Tuesday it approved the restart of a nuclear power plant after scheduled maintenance.     The plant is expected to work fully by Friday, reactor operator Korea Hydro & Nuclear Power Co Ltd  
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   (KHNP) was quoted as saying in a statement issued by the Nuclear Safety and Security Commission.     A spokesman at KHNP told Reuters that the reactor will start operation early on Wednesday.     The restart of Wolsong No.4, shut since May 17, comes during the peak demand season, with households and businesses cranking up air conditioners to avoid the summer heat.      The government said last month that power supply would be stable this summer, thanks to new generating capacity and fewer closed nuclear power plants.  
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       The country's nuclear reactors supply about a third of its electricity, and details on South Korea's 23 nuclear reactors are follows:     NAME            CAPACITY     OFFLINE STATUS                     (megawatts)     Kori No.1            587                                         Kori No.2            650          Kori No.3            950          Kori No.4            950     Shin Kori No.1     1,000                                         Shin Kori No.2     1,000                                           Hanbit No.1          950                              Hanbit No.2          950          Hanbit No.3        1,000          Hanbit No.4        1,000                                           Hanbit No.5        1,000          Hanbit No.6*       1,000     scheduled maintenance                                  (May 16-July 15)          Wolsong No.1*        679     offline with lifespan expiry          (no deadline given for life-span extension approval)      Wolsong No.2*        700     scheduled maintenance                                  (July 4-August 4)     Wolsong No.3         700     Wolsong No.4*        700     scheduled maintenance                                  (May 17-July 16)     Shin Wolsong No.1  1,000                                           Hanul No.1           950     Hanul No.2           950     Hanul No.3*        1,000     scheduled maintenance                                  (March 8-July 30)      Hanul No.4         1,000     Hanul No.5         1,000     Hanul No.6         1,000          Note: Reactors marked * are currently offline.           Details of upcoming 11 reactors are as follows (in megawatts):              NAME              CAPACITY   DUE DATE               Shin Wolsong No.2*  1,000    July, 2014     Shin Kori No.3*     1,400    Aug, 2014     Shin Kori No.4*     1,400    Sept, 2014     Shin Kori No.5**    1,400    Sept, 2014-Dec, 2019     Shin Kori No.6**    1,400    Sept, 2014-Dec, 2020     Shin Hanul No.1     1,400    April, 2017     Shin Hanul No.2     1,400    Feb, 2018         Shin Hanul No.3***  1,400    June, 2021     Shin Hanul No.4***  1,400    June, 2022     Shin Kori  No.7***  1,500     Shin Kori  No.8***  1,500             Note: Construction completion of three reactors marked by * has been delayed to replace cable supplied with forged safety certificates. Two of the three also have power transmission construction issues.     Of the 11 reactors planned, only nine have concrete construction schedules.      ** The two reactors for which the government gave the green light for construction in January this year.  
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        *** Power plants planned but the government has not yet approved.     Source: Reactor operator Korea Hydro & Nuclear Power Co Ltd, which is fully owned by state-run utility Korea Electric Power Corp (KEPCO)  
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  .   (Reporting by Meeyoung Cho; Editing by Subhranshu Sahu)  ((meeyoung.cho@thomsonreuters.com)(+82 2 3704 5653)(Reuters Messaging: meeyoung.cho.reuters.com@reuters.net))  Keywords: NUCLEAR SOUTHKOREA/