Materials for spallation neutron sources, with emphasis on SNS facility
- Oak Ridge National Lab., TN (United States)
The materials requirements in a high-power spallation neutron source like the SNS are particularly demanding. Materials at the target station are of special concern; these include the containment vessel and protective shroud for the mercury target material, beam windows, support structures, moderator housings, and beam tubes. The material chosen for the mercury containment vessel is Type 316 stainless steel (316SS). This choice is based on the extensive background of experience with 316SS and on its good fabricability and availability. While much has been learned about the effect of radiation on the properties of 316SS, the preponderance of this information stems from fission reactor irradiations, where the average neutron energy is only 1 to 2 MeV and relatively few neutrons are present with energies above {approximately}10 MeV. By contrast, the energies of the spallation neutrons at the SNS extend up to the 1000-MeV energy of the incident protons. However, because of the design of the target module, irradiation creep is not expected to be a significant problem. The major concern is for radiation embrittlement. Mercury is known to be an aggressive medium, and corrosion and compatibility studies for 316SS and INCONEL 718 are included in the research and development program on SNS materials. INCONEL 718 is under consideration as a beam window material. Two issues are receiving particular attention: liquid-metal embrittlement and temperature gradient mass transfer. Constant-strain-rate tensile tests were conducted in mercury and mercury-gallium at 23 C for 316SS and INCONEL 718 and at 100 C for 316SS; in all the tests there was no evidence of liquid metal embrittlement. In addition, preliminary mass transfer tests on 3165SS or INCONEL 718 at temperatures up to 350 C reveled no significant effects. Fatigue tests in mercury have recently been initiated. As a partial simulation of SNS conditions, they provide a more severe probe for possible ductility loss associated with a liquid-metal environment.
- OSTI ID:
- 678116
- Report Number(s):
- CONF-990605-; ISSN 0003-018X; TRN: 99:009101
- Journal Information:
- Transactions of the American Nuclear Society, Vol. 80; Conference: 1999 annual meeting of the American Nuclear Society (ANS), Boston, MA (United States), 6-10 Jun 1999; Other Information: PBD: 1999
- Country of Publication:
- United States
- Language:
- English
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