Elsevier

Fusion Engineering and Design

Volume 124, November 2017, Pages 767-773
Fusion Engineering and Design

The European ITER Test Blanket Modules: EUROFER97 material and TBM’s fabrication technologies development and qualification

https://doi.org/10.1016/j.fusengdes.2017.04.051Get rights and content

Highlights

  • Gaps analyses identifying missing data for EUROFER97 material and joints performed.

  • Design rules for EUROFER97 specific constitutive behavior identified.

  • Significant progress on development of welding procedures for European TBM achieved.

  • Fabrication processes feasibility based on diffusion and fusion welding demonstrated.

  • Methodology for qualification of the developed TBMs’ welding procedures identified.

Abstract

The paper overviews activities focused on qualification of EUROFER97 structural material, introduced under a probationary phase in the nuclear components design and construction code RCC-MRx, and identification/analyses of gaps in the respective material database to be filled in. Additionally the available design rules in the code are reviewed to verify their applicability to the specificities of EUROFER97 steel and to the TBM design and fabrication. Progress achieved in development of fabrication technologies and procedures applied for manufacturing of the TBM sub-components, like, HCLL and HCPB cooling plates, stiffening plates, first wall and side caps, and for TBM structure sub-assembly is described. The used technologies are based on fusion (laser and TIG) and diffusion (HIP) welding techniques taking into account specificities of the EUROFER97 steel. With help of the agreed notified body, an appropriate approach/methodology for qualification of the developed, TBMs-related preliminary welding procedure specifications has been identified and future steps established.

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:

  • 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).

  • 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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