D. Buckthorpe (Sp), M. Davies, J. Baker, AMECNNC Ltd., Knutsford, Sheshire (UK); I. Hugon, Y. Lejeail,
CEA, Grenoble (France); J. Hegemann, J. van der Laan, A. Vreelings, Nuclear Research and
Consultancy Group NRG, Petten (Netherlands); O. Gelineau, AREVA-NP-SAS, Lyon (France); R. Hurst,
M. Musella, European Commission, Joint Research Centre JRC, Petten (Netherlands); B. Schogl,
Research Centre Juelich (Germany); D. de Lorenzo, Empresarios Agrupados Internacional SA, Madrid
(Spain); B.-C. Friedrich, AREVA-NP-SAS GmbH, Erlangen (Germany); M. Blatt, Electricitie de France
EdF, Strasbourg (France); M. Marek, NRI Rez. (Czech Republic); J. Chen, Paul Scherrer Institute,
Villingen (Switzerland); K. Hingst, B. Tahon, SGL Carbon Group, Wiesbaden (Germany); P. Homerin,
Graphtech Intern Ltd, Jeumont (France); G. Hall, University of Manchester (UK)
This paper reviews the materials research and development activities completed and underway within the
European fifth and sixth Framework programmes (5FP & 6FP) for the developing Very High Temperature Reactor
(VHTR) and Gas Cooled Fast Reactor (GCFR) systems. The work for the VHTR is performed in the HTR-M & M1
programmes of the 5FP and the RAPAHEL and EXTREMAT programmes of the 6FP. The work for the GCFR takes
benefit from both RAPHAEL-IP and EXTREMAT-IP recognising that the VHTR system operates at potentially much
higher temperatures and therefore acts as a pilot for many of the materials issues that need to be addressed by
the GCFR. However there are additional issues for the GCFR (e.g. higher fast fluence, high transient
temperatures), which may impact on materials selection and require further R & D.
The VHTR modular reactor offers significant advantages for long-term development of sustainable energy and in
particular for heat applications and hydrogen generation. The GCFR system, which features a fast-spectrum
helium-cooled reactor and closed fuel cycle is also capable of delivering electricity, hydrogen, or process heat with
a high conversion efficiency. Both systems can operate with either a direct or indirect cycle. The reference
concept for the GCFR uses a direct-cycle helium turbine. For the VHTR both the pebble bed (e.g. PBMR) and block
type (e.g. ANTARES) are under development. For such new Generation IV type reactors it is important to have a
good understanding of the limits of the materials used and the behaviour of the main components under the
expected operating requirements. The 5FP materials programmes HTR-M & M1 that started in 1999 and 2000
respectively addressed material requirements for the HTR focussing on the reactor pressure vessel, high
temperature components (including turbine), and the graphite core. The main highlights from these results are
reviewed and examined in this paper. For the 6th Framework RAPHAEL-IP, which started in 2005 to look at the
VHTR, the main emphasis on materials is on graphite development, heat exchangers, vessel qualification and
design code requirements. The well-established European High Temperature Reactor Technology Network HTR-TN
serves as the platform for the coordination of these various projects.
Within the above projects there are also significant synergies with the materials developments for the Fusion
Reactor. Joining processes for example involving the bonding of similar and dissimilar materials developed initially
in the Fusion industry are becoming increasingly used in advanced fission heat exchanger design for economy and
compactness. The synergies between Fission and Fusion are especially visible in the EXTREMAT-IP which benefits
from the close involvement of a wide range of applications (fission, fusion, aerospace, automotive, etc. ). For the
advanced fission reactors the work within the EXTREMAT-IP addresses the potential of new materials for the
reactor control rod (irradiation resistance), for high temperature components such as the heat exchangers, and
for protection against corrosion damage (barrier materials). Within the EXTREMAT-IP the main materials
addressed for these applications are carbon composites, ODS steels and graphites where a database to store the
results of irradiation resistant materials tests is also being implemented.
The main results reviewed in this paper for these two reactor systems are as follows:
Pressure Vessel: results and planned tests, database developments for Mod 9Cr 1Mo steel welded joints under
irradiated and non-irradiated conditions to determine suitability for vessel application.
High Temperature materials : Irradiated and non irradiated results from investigations and database
developments for selected materials (carbon/carbon (C/C) composites, high alloy steels, etc. ) plus tests at
temperature, under short and intermediate times, and simulated carburising and de-carburising environments
Reactor Core: results from investigations, database developments and tests on graphites & carbon composites,
irradiation tests at temperature (750 & 950oC) for the VHTR core, development of micro-structural modelling &
guidelines for graphite and composites
The Generation IV International Forum is investigating the VHTR and the GCFR as two of the six systems of
interest for meeting the Generation IV goals of attaining highly economic, safe, reliable, sustainable, proliferationresistant
systems. Significant parts of RAPHAEL will be shared with the signatories of the GIF VHTR projects as
part of the Euratom contribution to Generation IV.