L. Petrizzi

European achievements for ITER high heat flux components

This paper summarises the main activities carried out by the EU Home Team to develop suitable solutions for the ITER high heat flux components, namely the divertor, the baffle and the limiter. The available results demonstrate that the EU have the capability to manufacture high heat flux components with carbon fibre reinforced carbon, tungsten and beryllium armours which all exceed the ITER design requirements.

Sensitivity and uncertainty analyses of 14 MeV neutron benchmark experiment on silicon carbide

Abstract A shielding experiment on a silicon carbide (SiC) composite, a potentially important low activation structural material for the fusion reactor, was performed at the 14 MeV Frascati Neutron Generator (FNG) in 2001 and analyzed using both deterministic and probabilistic transport, sensitivity and uncertainty methods. The objective of the experiment was to verify the nuclear cross section files, as well as the calculational methods, used in the design and shielding calculations for fusion reactor. Neutron activation reaction rates, neutron and photon flux spectra, and nuclear heating rates were measured at several positions inside the SiC block. Point-wise and group cross sections derived from the European Fusion File (EFF-2.4 and -3.0) and the Fusion Evaluated Nuclear Data Library (FENDL-2) were used in the analysis. Results indicate that the calculation based on the recent EFF-3.0 Si-28 nuclear data estimates the measured quantities with a reasonable uncertainty of ±(10–15)% for 1 σ.

ITER reference breeding blanket design

The ITER reference breeding blanket design is water-cooled and is characterised by the use of the neutronic multiplier and breeder materials in the form of pebbles. Besides the achievement, with margin, of the tritium breeding ratio (TBR) minimum requirement, it exhibits an internal layout allowing it to withstand properly electromagnetic loads during plasma disruption and vertical displacement events, and pressure loads in case of rupture of an internal cooling channel (i.e. in-box LOCA). During the first part of 1998, the design has been optimised improving the performance in terms of TBR, enlarging the design margins with respect to the dimensioning loads and investigating in detail the global behaviour of the system during normal and off-normal conditions.

Three-dimensional neutronic analysis of the European ceramic BIT DEMO blanket

Abstract The present study concerns the 3-D geometry evaluations of the tritium breeding ration of the breeder-in-tube helium-cooled ceramic blanket performed at CEA and ENEA in the framework of the recently released DEMONET specifications. For the calculations the nuclear data have all been derived by the European Fusion File (EFF-1), but different Monte Carlo codes, and different design variants and geometrical models have been used. A benchmark calculation has been defined in order to better analyse the results; such an exercise has shown that TBR differences of a few percent could be due to the calculation methods. The determined global TBR ranges from 1.06 in the CEA results to 1.15 in the ENEA results, the expected difference being mainly due to the greater neutron coverage of the ENEA variant of the design. Heat deposition density and He production in beryllium are also given.

Design of plasma facing components for the ITER feat divertor

Abstract A comprehensive design of the ITER divertor has been developed within the EU R&D for ITER. It consists of plasma facing components (PFCs) and cassettes body (CB). The PFCs are actively cooled thermal shields while the CB are massive supports for the PFCs providing also a neutronic shield. The present paper gives a detailed design of the PFCs and the CBs. It includes the cooling path, the manifolds, the attachments between the PFCs and the CBs and those between the CBs and the vacuum vessel (VV). The design has been carried out with a series of analyses. The neutronics analysis assures the shielding efficiency of the PFCs/CBs towards the rear components, and calculates the radiation loads in the key points. The electromagnetic (EM) analysis evaluates the loads due to eddy and halo currents. The thermo–hydraulic analysis verifies the effectiveness of the cooling circuit regarding the minimum margin critical heat flux (CHF) and the maximum acceptable pressure drop. The thermo-mechanical analysis verifies the integrity of the components under coolant pressure, neutron/plasma thermal loads and EM loads. The work, done with the collaboration of professionals from different organisations, shows that the proposed design of the components fulfils all the requirements of the ITER FEAT machine.

Convertible liquid metal blankets for ITER with Pb-17Li as breeding material

Abstract A convertible blanket concept is proposed for ITER, where, without replacement of the blanket structure, a non-breeding Pb alloy is used during the basic performance phase and the eutectic Pb-17Li during the enhanced performance phase. The concept is based on austenitic steel as structural material, an average neutron wall load of 1 MW m−2 and either helium or water as coolant. The same design concept was used for both coolant options with respect to a stiff blanket segment box, direct cooling of the first wall using toroidal ducts, poloidal hairpin tubes to cool the quasi-stagnant liquid metal and tritium removal outside the vacuum vessel. Various design options were considered for the first-wall and pool cooling and corresponding headers. Owing to the different coolant properties, different combinations were selected for the two versions. The performance of the two versions was assessed among other things with respect to tritium breeding and control, reliability and R&D needs.