The European ITER Test Blanket Modules: EUROFER97 material and TBM’s fabrication technologies development and qualification
Introduction
For several years, European Union and other ITER Members have been developing tritium breeding blankets concepts that will be tested in ITER under the form of Test Blanket Modules (TBMs) located in equatorial ports of ITER. Up to 6 TBM concepts will be tested simultaneously in ITER [1].
Europe is currently developing two reference breeding blankets concepts based on DEMO reactor specifications that will be tested in ITER under the form of TBMs [2], [3]: i) the helium-cooled lithium-lead (HCLL) concept which uses the eutectic Pb-16Li (enriched in 6Li) as both tritium breeder and neutron multiplier, ii) the helium-cooled pebble-bed (HCPB) concept with lithiated ceramic (enriched in 6Li) pebbles as tritium breeder and beryllium pebbles as neutron multiplier. Both concepts are using a reduced activation ferritic-martensitic steel as structural material, the EUROFER97 (X10CrWVTa9-1) [4], [5], and pressurized helium as a coolant for efficient heat extraction (300–500 °C, 8 MPa).
Both TBM concepts (see Fig. 1, Fig. 2) consist of a EUROFER97 steel box with an internal stiffening grid which provides mechanical resistance and segregates the volume into cuboids containing breeder/multiplier materials and heat extraction cooling plates (CP). The EUROFER97 steel structures of various thicknesses are actively cooled by circulation of pressurized helium in embedded, internal channels having a rectangular or square shape of different dimensions which meander in a number of U-turns (HCLL CP, stiffening plates, side caps) or are in a form of parallel channels (HCPB CP).
A manifold system located at the back of the TBM ensures the distribution/collecting of helium to/from the various parts of the TBM structures, in a way that optimizes the temperature of TBM materials according to their function.
Section snippets
Regulatory framework
TBMs are structures that intend to be operated inside an experimental reactor ITER which is a nuclear facility (so-called INB, installation nucleaire de base) and as such they have to fulfil specific requirements of basic nuclear installation to assure the quality of design, construction and operation. Consequently the French and European regulations define the general essential safety requirements (ESR) and some technical guidelines. As nuclear pressure vessel equipment, the TBMs have to
EUROFER97 material qualification
This section explains the strategy toward the qualification of the EUROFER97 steel that is to say all the activities necessary for its introduction within the nuclear design code RCC-MRx.
TBMs’ fabrication technologies development and qualification
This section provides a brief survey of the developed fabrication technologies related to the TBMs and describes the way how these fabrication technologies are intended to be qualified.
The fabrication processes feasibility for TBM EUROFER97 subcomponents, i.e. first wall (FW), side cap (SC), horizontal and vertical stiffening plate (hSP/vSP) and cooling plates (CP), and for the TBM assembly by welding was previously demonstrated at laboratory scale [12] and their transfer in an industrial
Conclusions
Europe has made an important progress towards qualification of EUROFER97 material and its introduction into the RCC-MRx code and development and future qualification of standardized welding procedures for TBMs. The following main achievements can be identified:
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Complete gaps analyses to identify missing data to fill-in the both base metal and welded joints material appendices (respectively A3.19AS and A9.J 19AS).
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Identification of the design rules to adapt or to develop for the EUROFER97 specific
Acknowledgments
The work leading to this publication has been funded by Fusion for Energy under the contracts F4E-OPE-305, F4E-OMF-331-05-01, F4E-OMF-545-01, F4E-OFC-413-03/04-01 and F4E-FPA-603-01-01. This publication reflects the views only of the author, and Fusion for Energy cannot be held responsible for any use which may be made of the information contained therein.
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