RAMI studies for DONES

The DONES (Demo Oriented NEutron Source) objective is to irradiate in a simulated fusion irradiation environment a sufficiently large number of specimens with required neutron fluxes for an adequate period of time. To achieve the required results, a target of 70% of operational availability was established for DONES facility design, which means that, the facility is expected to be available for irradiation (i.e. with the beam on at full power) for 255.5 d per year. Such an average operational availability requirement combined with the foreseen scheduled annual maintenance scheme (20 + 3 d) implies an inherent availability requirement of 74.7% (i.e. ∼75 %) for the DONES facility. Allocating this target to individual systems within the whole plant, the following system targets for inherent availability were defined: Accelerator Facility 87 %, Lithium Target Facility 94 %, Test Facility 96 %, Conventional Facilities 98% and Central Control System & Common Instrumentation 98 %. Key elements to ensure the availability objective set for a complex and innovative plant such as DONES are to accompany the engineering development of DONES with reliability and availability (RA) analysis, reliability testing of components and systems and the application of ‘reliability growth’, the structured process of identifying the root causes of reliability problems and predicting and monitoring the increase in system reliability through successive phases. Since RA are closely linked to the maintenance and inspection activities carried out during plant operations, the integrated approach for RA optimization needs to be based on all four issues: Reliability, Availability, Maintainability and Inspectability (RAMI). Accordingly, RAMI analyses cover all stages of DONES progress and specific studies have been performed for the various systems. This paper presents the RAMI studies conducted to date.