Short-Term Solubility of Eight Alloys Circulating in Mercury at Room Temperature

Because mercury is a dense liquid at room temperature, it has found application in particle-accelerator targets with high energy-deposition rates such as proton spallation targets. Such targets usually require an active heat-removal system to remove the energy deposited by the particle beam, energy deposition rates that can be as much as several megawatts Ž . Weeks, 1996 . Solid targets generally require a water-cooling system that can introduce significant complexities into the system. However, a mercury target has several advantages over a solid target, one of which is that the mercury itself can be circulated to remove the deposited heat. Although the service lifetime of a mercury target container may be limited by corrosion or erosion caused by the flowing mercury, the present authors found it difficult to retrieve clear guidance from the literature for our application on the compatibility of various alloys with circulating mercury and even less guidance on the effects of radiation. Although one approach to a potential mercury incompatibility problem could be to schedule periodic removal of a target assembly for examination and possible replacement, it would be useful to have experimental evidence of the performance of a material under representative conditions prior to actual service. In order to be useful for application in a mercury-wetted environment, a material should form no solid alloys with Ž . mercury Weeks, 1967 . Since nickel is known to form intermetallic compounds with mercury as well as with lead and bismuth, it has been recommended that austenitic steels or other alloys with more than a trace of nickel be avoided for Ž . use with mercury Weeks, 1997 . Also, chromium is soluble in heavy liquid metals. Therefore, chromium depletion at surface grain boundaries of seasoned steels can be a concern when in contact with mercury. In spite of these concerns, the Spallation Neutron Source project under construction at the Oak Ridge National Laboratory is using 316L Stainless Steel for the mercury target container, and no such difficulties have been observed in laboratory and proton irradiation experiments with 316L Stainless Steel vessels containing mercury Ž . National Spallation Neutron Source, 1997; Haines, 2002 . The muon collider project is also proposing to use mercury