Spallation Neutron Source Availability Top-Down Apportionment Using211 Characteristic Factors and Expert Opinion

摘要

System design engineers must translate permitted overall facility downtime into211u001edetailed design and operating specifications for numerous systems and subsystems 211u001ethat make up a facility. The process of assigning reliability and maintainability 211u001erequirements to individual equipment systems to attain their desired overall 211u001eavailability is known as availability apportionment. Apportionment is normally 211u001erequired early in a program when little or no hardware information is available. 211u001eApportionment is a continuous process during design and development, with 211u001esubsequent re-allocations performed as further information regarding the 211u001econtribution of various subsystem elements to the top-level requirement becomes 211u001eavailable. Apportionment, when coupled with availability prediction, enables the 211u001eselection of viable alternative configurations, identifies problem areas, and 211u001eprovides redirection of the program into more productive areas as necessary. A 211u001emethod for apportioning overall facility availability requirements among systems 211u001eand subsystems is presented. The application of this methodology to the 211u001eSpallation Neutron Source (SNS) facility is given as an example of apportionment.