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Case History - Mercury Pump LaBour Supplies Oak Ridge National Lab:
LaBour Pump recently delivered, to the U.S. Department of Energy Spallation Neutron Source (SNS) project, a Taber brand pump that will be installed in a spallation neutron bombardment system. The SNS is an accelerator-based neutron source being built in Oak Ridge, Tennessee. The world’s most powerful-pulsed neutron beams will be produced in the SNS. These beams are then used for scientific research and use in industrial developments.
Neutron scattering science impacts our daily lives in ways most people don’t realize. Many items used on a daily basis have been improved using neutron scattering research. Included in this list are electronic devices, shatterproof windshields, satellite based weather forecasts and credit cards.
Neutron research also helps researchers improve materials used in high-temperature superconductors, powerful lightweight magnets, aluminum bridge decks, and stronger, lighter plastic products. In the lab’s mercury process system, a 2MW proton beam, driven by a super-conducting linear accelerator, will collide with a liquid mercury target. Interaction of the high energy (1 GeV) protons with the mercury atoms will result in a nuclear reaction known as spallation. The reaction yields an abundant number of neutrons that will be moderated, and then collimated to 18 different instrumentation cells for civilian materials research. Mercury is not only the target but also the coolant for the target vessel walls. The system will operate continuously for about 5000 hrs./yr.
The Taber pump (Model 9080-50) is a cantilever design, with 316 stainless steel wetted components and contains a 15-inch open impeller. Leakage is prevented using a gas seal. The application requires that liquid mercury be pumped around a cooling loop, which surrounds the bombardment system.
The pump operates at 200 degrees F at 430 GPM and at 23 ft. head. The application requires the Taber pump to be bombarded with nuclear radiation thus the pump must maintain 100% reliability, be fail safe and maintenance free. At the end of its useful life, the pump will be removed and buried in concrete. The pump will operate around the clock and key design criteria included speed variability, radiation resistance and maintainability via robotics.
Since Mercury has a specific gravity of 13.6, much heavier than water, questions surrounding use of a centrifugal pump were aired. The Taber made the cut. For safety reasons, the Taber pump was installed in an ASME Section 8 coded vessel. “Balloons” were installed around the pump body to minimize the volume of mercury in the pump. It is believed to be the largest mercury pump ever built.
Operation of the Spallation Neutron Source (SNS) project will begin full-scale operation in 2006.