The IFMIF-DONES facility is aimed at providing a database of materials exposed to similar irradiation conditions as in DEMO. For this purpose, a neutron source facility will be built, consisting of a superconducting linear Accelerator Systems (AS) generating a deuteron beam impacting onto a target made of a liquid lithium jet provided by the Lithium Systems (LS).
An important aspect of the project design activities is to assess the system reliability at all phases of the facility life cycle to support a reliability growth during the ongoing design phase and to monitor the compliance with the stated availability targets.
In DONES facility, AS and LS are functionally and physically entangled. In fact, AS operation has an interlock dependency on the LS which can be “ready or not ready for beam” since the liquid lithium jet must be ready to receive the 5 MW power of the accelerator. In this context, the present study focuses on the failures arising in LS that can lead to a beam interlock to the AS.
Following RAMI methodology, first a Failure Mode and Effect Analysis (FMEA) is done in order to point out all the relevant unavailability conditions in the LS subsystems (lithium loop, secondary and tertiary cooling loops and target system) that could lead into a shutdown event on the AS. Then, Reliability Block Diagrams (RBDs) are derived from FMEA by implementing a reliability-wise representation of system component behavior and simulating the system performance under due operating conditions.
As outcome of the RAMI, information on the expected total downing events, total downtime and criticality for a given period can be derived. This offers valuable information about LS failures impacting on AS operation that can be presented as number of events in the AS caused by the LS per period of time.