David Rapisarda

Development of sandwich flow channel inserts for an EU DEMO dual coolant blanket concept

Abstract The dual-coolant lead-lithium (DCLL) blanket concept, which is considered as a candidate for fusion power plants and possibly for a demonstration reactor (DEMO), is being investigated within the framework of the European Power Plant Physics and Technology (PPPT) study. One of major issues of the DCLL concept development is the design of the flow channel inserts (FCIs), which are essential for the reduction of magneto-hydrodynamic (MHD) pressure losses. Due to the tight schedule for the short-term PPPT DEMO, a low-temperature DCLL concept with a liquid metal outlet temperature below 500 °C has been proposed. This allows the use of a simpler type of FCI (taking into account the LM corrosion issues), e.g. Eurofer-Alumina-Eurofer sandwich FCI, instead of the SiCf/SiC version for high temperature case, the production thereof is challenging. This paper discusses the technological study on manufacturing of some FCI design variants and post-examination of the samples.

Tritium production assessment for the DCLL EUROfusion DEMO

The viability of a fusion reactor is preeminently conditioned by the tritium self-sufficiency. An assessment of different parameters representing the tritium production, as the tritium breeding ratio (TBR), the tritium production rate (TPR) density and their poloidal and radial variations along the PbLi breeder zones has been performed for the last DCLL DEMO designs developed in the frame of the EUROfusion Programme. The final overall value of 1.104 obtained allows accomplishing the fuel self-sufficiency requirement. This TBR value includes not only the contribution of the breeding blanket (BB) modules but also of the back supporting structure (BSS). The BSS design resulted fundamental to reach the 1.1 criterion. Lastly, the influence of the integration in the reactor of the heating and current drive (H&CD) systems that will penetrate the breeder volume has been evaluated. Assuming different configurations for them, the TBR loss has been determined. All the calculations have entailed the use of the particle transport Monte Carlo code MCNP5.

Tritium Behavior in HCPB Breeder Blanket Unit: Modeling and Experiments

Abstract Tritium behavior in a breeding blanket is a key design issue because of its impact on safety and fuel self-sufficiency best performance. Considering the difficulty in handling and its high cost, it is intended to prepare a simulation tool for tritium transport in the HCPB (Helium Cooled Pebble Bed) breeder blanket unit concept. The objective of this work is to evaluate tritium inventory inside several components of the breeder unit (pebble bed and purge gas) and its permeation into the coolant. Some simplified assumptions have been adopted and the results compared with others studies obtained by different simulation tools. Finally an example in which different experimental values of tritium residence time in ceramic breeder is presented with the purpose to observe the capability of the program to be integrated with experimental campaigns.

Requirements and ideas for the neutron instrumentation of the IFMIF test facilities

IFMIF will be an accelerator-based neutron source, currently under engineering design phase, with the purpose of testing and fully qualify fusion candidate materials. Fission chambers were identified as good candidates to control on-line the irradiation level and mapping of the flux reaching the irradiated specimens. However, their use within the harsh environment of IFMIF (neutron fluxes up to 1011–1015 neutrons/cm2/s, fluence up to 2x1022 neutrons/cm2, gamma doses of about 104 Gy/h, high temperatures, etc) is still under a validation process. It is necessary then, the assessment of another kind of diagnostics, in order to get complete and redundant information concerning the radiation field. In this line, the present work proposes diagnostics based on optical measurements and particle interactions. They consist of a radiation monitor for the IFMIF - High Flux Test Module (the module receiving higher neutron doses) based on the radioluminescence of specific materials; and a radiation monitor which measures the fluorescence of the Test Cell atmosphere. The experimental system will have to be capable of measuring the high neutron fluxes expected for IFMIF, substituting or complementing the information of the fission chambers.