Spallation Neutron Source Availability Top-Down Apportionment Using Characteristic Factors and Expert Opinion

摘要

System design engineers must translate permitted overall facility downtime into detailed design and operating specifications for numerous systems and subsystems that make up a facility. The process of assigning reliability and maintainability requirements to individual equipment systems to attain their desired overall availability is known as availability apportionment. Apportionment is normally required early in a program when little or no hardware information is available. Apportionment is a continuous process during design and development, with subsequent re-allocations performed as further information regarding the contribution of various subsystem elements to the top-level requirement becomes available. Apportionment, when coupled with availability prediction, enables the selection of viable alternative configurations, identifies problem areas, and provides redirection of the program into more productive areas as necessary. A method for apportioning overall facility availability requirements among systems and subsystems is presented. The application of this methodology to the Spallation Neutron Source (SNS) facility is given as an example of apportionment.