Maintenance Job in the Pohang Light Source

        J.Choi, M.G.Kim, T.-Y. Lee, M.H.Cho, M.kwan, and I.S.Ko
        San 31, Hyoja-dong, Pohang Accelerator Laboratory, POSTECH
                        Pohang, 790-784, KOREA

   The Pohang Light Source (PLS) is the first synchrotron light source
   in Korea.  It consists of a 150-meter long 2-GeV injection linac
   and a 280-meter circumference storage ring.  Its operational
   mission is to supply users as many hours of beam time as possible. 
   Therefore the maintenance schedule is restricted by the machine
   operation schedule.  Only one full day is reserved for maintenance
   in two weeks.  The software maintenance and gathering statistics
   are governed by the operation group.  The machine maintenance of
   the linac and the storage ring are governed by separate groups. 
   Two long-term shutdowns of 4 to 5 weeks are reserved in summer and
   winter, when major maintenance works and machine upgrades are
   performed.  It is our concern to improve the efficiency of the
   maintenance job while increasing the beam-supplying time to users. 
   In the poster, details of the PLS maintenance are presented.


         Table 1.  Accelerator failures in 1997

     |-------------------------------------------------------|
     |   Storage Ring   |        |      Linac       |        |
     |------------------+--------+------------------+--------|
     | RF system        |   65   | Modulator        |  127   |
     |------------------+--------+------------------+--------|
     | MPS system       |   48   | Control system   |   35   |
     |------------------+--------+------------------+--------|  
     | Control system   |   28   | MPS system       |   30   |
     |------------------+--------+------------------+--------|  
     | LCW system       |   19   | Timing system    |   25   |
     |------------------+--------+------------------+--------|  
     | Vacuum system    |   18   | Vacuum system    |    8   |
     |------------------+--------+------------------+--------|  
     | Interlock system |   13   | Power failure    |    8   |
     |------------------+--------+------------------+--------|  
     | Timing system    |   12   | Microwave system |    3   |
     |------------------+--------+------------------+--------|  
     | Power failure    |    6   | Electron gun     |    1   |
     |------------------+--------+------------------+--------|  
     | Injection system |    5   |                  |        |
     |------------------+--------+------------------+--------|  
     |     TOTAL        |  214   |    TOTAL         |  231   |
     |__________________|________|___________________________|