Developing a Reliability Database Using Records
           from Existing Accelerator Facilities

  Christopher Piaszczyk
  Northrop Grumman Corporation


    
     The next generation of high power-accelerators (e.g., the International
 Fusion Materials Irradiation Facility, the Spallation Neutron Sources, the
 Accelerator Production of Tritium, and the Accelerator Transmutation of
 Waste) currently in planning stages has availability requirements which will
 push the reliability and maintainability requirements for these machines to
 highly challenging levels.  In order to reach these goals a thorough 
 understanding of the experience accumulated in existing accelerator facilities
 is necessary to provide a solid basis on which to plan operations and
 designs.  The present study consists of a literature search and visits to
 selected locations to gather information for subsequent analysis.  Initial
 analyses of some of that data have already been performed and preliminary
 account of the results of these analyses are also described here.  

     The ultimate objective of the present effort is to assemble a database of
 reliability information for typical components of accelerators: ion sources,
 focusing magnets, magnet power supplies, RF windows, circulators, high
 voltage components, etc.  The resulting database will be used in support of
 the design effort which is already underway.  The approach, based on standard
 reliability theory, is predicated on the assumption that although the
 surveyed accelerator facilities are complex and different in details, they all 
 share common types of equipment and operational characteristics.  Moreover,
 they share common elements and characteristics with the future machines as
 well.  It is therefore possible to use their operational experience to derive
 failure and maintenance rate information that will be applicable to the
 envisioned future concepts.

     We found that all the facilities maintain databases of downtimes and their
 causes (insofar as these are actually understood).  Generally, a significant
 amount of consistency was found among all the survey facilities, particularly
 in the area of operations.  The preliminary analysis confirmed that existing
 facilities consistently operate with availability between 80-90% of scheduled
 time.  This is accomplished via a dedicated effort and intelligent management
 of resources by people running these facilities since this level of
 performance exceeds that expected by analysis using standard published 
 reliability data.  On the cautionary side, it should be noted that the
 surveyed facilities are normally scheduled to operate only between 30% and
 50% of the year, thus allowing for a substantial amount of maintenance and
 up-grade work during the remainder of the time.  Efforts to extend the
 operating availability by reducing the length of the extended shut- down could
 degrade the availability of future machines due to the inability to perform 
 critical repairs.