Radionuclide deposition control

The deposition of the radionuclides manganese 54, cobalt 58, and cobalt 60 from reactor coolants such as liquid sodium is controlled by positioning a high-surface-area material of nickel or a high-nickel-content alloy in a flow of sodium containing manganese-54, cobalt-58, and cobalt-60 to effect deposition of the radionuclides on the materials, and subsequently separating the radionuclide loaded material from the sodium stream; and positioning components where deposition is undesirable having surface areas made of tungsten, molybdenum or tantalum in those areas where the liquid sodium flow is contacted. The high surface area material may be in the form of a radionuclide trap comprising an elongated cylindrical core, a nickel sheet of from about 0.13 mm to 0.25 mm thickness having several diagonal grooves on one face. This sheet of material may be wrapped around the elongated cylindrical core to form several layers of the sheet about the core. The diagonal grooves form long helical passageways for the passage of sodium through and the deposition of the radionuclides on the trap material. The nickel material may be suitably disposed in a housing which may then be located in reactor fuel element subassemblies adjacent to and immediately downstream of the fuel pins. (auth)