Fabio Borgognoni

Reliability and availability requirements analysis for DEMO: fuel cycle system

Abstract Two of the key elements of the engineering development of the DEMO reactor are the definitions of reliability and availability requirements (or targets). The availability target for a hypothesized Fuel Cycle has been analysed as a test case. The analysis has been done on the basis of the experience gained in operating existing tokamak fusion reactors and developing the ITER design. Plant Breakdown Structure (PBS) and Functional Breakdown Structure (FBS) related to the DEMO Fuel Cycle and correlations between PBS and FBS have been identified. At first, a set of availability targets has been allocated to the various systems on the basis of their operating, protection and safety functions. 75% and 85% of availability has been allocated to the operating functions of fuelling system and tritium plant respectively. 99% of availability has been allocated to the overall systems in executing their safety functions. The chances of the systems to achieve the allocated targets have then been investigated through a Failure Mode and Effect Analysis and Reliability Block Diagram analysis. The following results have been obtained: i) the target of 75% for the operations of the fuelling system looks reasonable, while the target of 85% for the operations of the whole tritium plant should be reduced to 80%, even though all the tritium plant systems can individually reach quite high availability targets, over 90% - 95%; ii) all the DEMO Fuel Cycle systems can reach the target of 99% in accomplishing their safety functions.

Design, manufacturing and testing of Pd-membranes and membrane reactors for detritiation processes

Pd-based dense membranes are used to separate hydrogen isotopes with infinite selectivity. Membrane modules have been studied for several detritiation processes in the fuel cycle of fusion reactors: plasma exhaust treatment, tritium extraction from the breeding blanket and detritiation of highly tritiated water.

Simulation Code for Wet Gas Detritiation Via Pd-Based Membrane Reactor

Abstract This paper presents a model and a simulation code which study a Pd-based membrane reactor for detritiating highly contaminated gas streams. A finite elements method has been applied for evaluating the mass balance equations taking into account the isotopic exchange reactions equilibrium and the permeation kinetics. The code has been validated by comparing the results of the inactive experiments carried out on a prototype Pd-Ag reactor where high D/H ratios have been used. Further, a parametric analysis for evaluating the effect of the temperature and membrane wall thickness on the water detritiation capability has been performed.