16.  MATERIALS FOR ADVANCED NUCLEAR ENERGY SYSTEMS

The Generation IV nuclear energy initiative is an international collaboration to identify, assess, and develop sustainable nuclear energy technologies that are competitive in most markets, while further enhancing nuclear safety, minimizing the nuclear waste burden, and further reducing the risk of proliferation (reference 1).  Many nuclear energy systems have been proposed to advance the goals of the Generation IV program (see references 2-5), including designs that use liquid-metal coolants such as sodium and gas coolants such as helium.  For the gas-cooled systems, operation at higher temperature has been identified as a means to improve economic performance and to support the thermochemical production of hydrogen.  However, the move to higher operating temperatures will require the development and qualification of advanced materials to perform in the more challenging environment.  As part of the process of developing advanced materials for these reactor concepts, a fundamental understanding of materials behavior must be established and a database that defines the critical performance limitations of these materials under irradiation must be developed.    Grant applications are sought only in the following subtopics:

a. Advanced Radiation Resistance Ferritic-Martensitic Alloys—Because of their resistance to void swelling, 9 Cr and 12 Cr ferritic-martensitic steels are considered prime candidates for intermediate temperature reactors such as the proposed liquid metal concept operating in the temperature range of 400-750°C.  However, many ferritic-martensitic steels are limited by poor higher temperature creep strength, typically degrading at temperatures greater than 550-600°C (reference 6).  Grant applications are sought to improve the creep strength of 9 Cr and 12 Cr ferritic-martensitic steels through alloying, dispersion strengthening, or precipitation hardening.  Innovative alloys with protective coatings are also of interest.  P roposed approaches must provide for (1) isotropic creep properties with strength greater than that of Sandvik HT9 steel, (2) a ductile to brittle transition temperature less than room temperature, and (3) a minimum plane-strain fracture toughness of 0.25σy.  Alloying elements that act as neutron poisons (e.g., boron) or that become highly activated in a neutron spectrum (e.g., cobalt) must be minimized or eliminated.  Because the ferritic-martensitic steels likely would be used in conjunction with a sodium-cooled reactor concept, approaches that optimize corrosion performance while achieving improved high temperature strength would be considered high priority.  Lastly, approaches that also address irradiation performance are strongly encouraged.

Questions – contact Sue Lesica (sue.lesica@hq.doe.gov)  

b. Advanced Refractory, Ceramic, Ceramic Composite, or Coated Materials—Some Generation IV concepts aim for very high temperature (>900°C) operation.  However, with the exception of limited data on SiC-based systems, the radiation resistance of construction materials subjected to very high temperatures has not been identified or proven.  Grant applications are sought to develop advanced refractory, ceramic, ceramic composite, or coated materials that can meet the very demanding conditions required to operate at temperatures greater than 900°C in a thermal spectrum nuclear energy system.  For these conditions, the materials should have low thermal expansion coefficients, excellent high temperature strength, excellent high temperature creep resistance, and good thermal conductivity.  For post-irradiation handling at lower temperatures, sufficient room temperature fracture toughness must be maintained.  Additionally, the materials need to be easily fabricated and capable of being joined.  Because the reactors operating in this temperature regime are expected to be helium cooled, the materials must have low erosion properties in flowing helium and be able to survive an air ingress condition.  Because the high temperature strength and corrosion resistance may be difficult to achieve with a single material, composite or coated systems may be required.  Finally, because sustainable nuclear energy systems may be based on fast spectrum (i.e., fast flux) designs, materials intended for fast reactor concepts should minimize the use of low atomic mass components such as hydrogen and carbon.

Questions – contact Sue Lesica (sue.lesica@hq.doe.gov)  

References:

1.      “Generation IV Nuclear Energy Systems,” U.S. DOE Office of Nuclear Energy, Science and Technology Website.  (URL:  http://gen-iv.ne.doe.gov)

2.      “Global Nuclear Energy Partnership,” U.S. DOE Office of Nuclear Energy, Science and Technology Website  (URL:  http://www.gnep.energy.gov)

3.      Kiryushin, A. I. et al., “BN-800:  Next Generation of Russian Sodium Fast Reactors,” Proceedings of ICONE 10, ASME, 2002.  ( P aper No. 10-22405)*

4.      Hittner, D., “The Renewal of HTR Development in Europe ,” Proceedings of ICONE 10, ASME, 2002.  ( P aper No. 10-22423)*

5.      King, R. L. and Porter, D. L., “ Performance of Key Features of EBR-II (Experimental Breeder Reactor II) and the Implications for Next-Generation Systems,” Proceedings of ICONE 10, ASME, 2002.  ( P aper No. 10-22524)*

6.      Klueh, R. L. and Harries, D. L., “High Chromium Ferritic and Martensitic Steels for Nuclear Applications,” West Conshohocken, PA:  American Society for Testing and Materials, 2001.  (ISBN:  0-8031-2090-7)

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*          Abstracts of papers and ordering information available through ASME at:  http://store.asme.org/category.asp?catalog%5Fname=Conference+Papers&category%5Fname=Tenth+International+Conference+on+Nuclear+Engineering&Page=1.  Search by Paper No. in citation above.)

 

 

 

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