Reliability evaluation of the two bus interface controllers in the Darlington simulator

Abstract

The Darlington simulator is now two decades old and, in common with any nuclear simulator of a similar age, suffers the problem of parts aging and obsolescence. In the past, replacement parts were available from the original vendor, Canadian Aviation Electronics. This is no longer an option, as the vendor has shown no interest in continuing to supply spare parts. Over the years, the Simulator Services Department has undertaken several projects. These projects were carried out aiming at different goals: (i) solving the problem with spare parts scarcity, (ii) modifying the simulator to adapt it to increased usage requirements, or (iii) upgrading the simulator to improve its reliability. One such project is the re-design of the Bus Interface Controller used in the I/O system of the simulator. The Bus Interface Controller is probably the most important piece of hardware in the whole I/O system. As such, it is important that reliability evaluation of the new design be carried out. Reliability has become increasingly important in the design of engineering systems. The key factor driving this is the demand of the customers [6]. The Darlington simulator usage time has always been consistently high, sometimes reaching the level of continuous use during some periods of the past years. The increase usage requirement creates a demand for higher availability, while the allocated maintenance time has been cut back substantially. The only way to meet this demand is to have better designs, where reliability consideration and evaluation are incorporated into the design cycle. Following this design methodology, during the early design cycle of the new Ethernet Bus Interface Controller, an analysis was done to evaluate its reliability. This report presents the details of the analysis and compares the reliability of the new design with the existing one.