System, method and apparatus for providing additional radiation shielding to high level radioactive materials

摘要

A system, method and apparatus for providing additional radiation shielding to a ventilated cask for holding high level radioactive materials. The invention utilizes a tubular shell that is ancillary to the ventilated cask that circumscribes the ventilated cask to add radiation shielding protection while improving heat removal by natural convective air flow. Because the tubular shell and cask are non-unitary and slidably separable from one another, crane lifting capacity is not affected. In one aspect, the invention is an apparatus for providing additional radiation shielding to a cask holding high level radioactive materials comprising: a tubular shell extending from an open bottom end to an open top end, the tubular shell having an inner surface that forms a cavity about a longitudinal axis; a plurality of primary apertures forming passageways through the tubular shell and circumferentially arranged in a spaced-apart manner about the tubular shell; a plurality of secondary apertures forming passageways through the tubular shell and circumferentially arranged in a spaced-apart manner about the tubular shell; and an annular seal coupled to the tubular shell and extending from the inner surface of the tubular shell; wherein the secondary apertures are located at an axial height above the annular seal and the primary apertures are located at an axial height below the annular seal.

主权项

1. A system for containing high level radioactive materials comprising:
a cask extending along a longitudinal axis and having an internal cavity for holding high level radioactive materials, the cask comprising at least one inlet vent at a bottom end of the cask for allowing cool air to enter the internal cavity and at least one outlet vent at a top end of the cask for allowing heated air to exit the internal cavity; a tubular shell extending from a bottom end to a top end, the tubular shell positioned to circumferentially surround the cask in a spaced apart manner so that an annular gap exists between the tubular shell and a sidewall of the cask, the tubular shell comprising at least one primary aperture forming a passageway through the tubular shell and at least one secondary aperture forming a passageway through the tubular shell; and an air flow barrier extending between the tubular shell and the sidewall of the cask that separates the annular gap into: (1) a first chamber that forms a passageway between the primary aperture and the inlet vent of the cask; and (2) a second chamber that forms a passageway between the secondary aperture and an opening at the top end of the tubular shell, wherein cross-flow of air between the first and second chambers of the annular gap is prohibited by the air flow barrier, wherein the primary aperture is configured as a first air flow inlet for the first chamber, for air to flow into the primary aperture, through the first chamber, and to the inlet vent of the cask, the primary aperture being located at an axial height below the air flow barrier, and wherein the secondary aperture is configured as a second air flow inlet for the second chamber, for air to flow into the secondary aperture, through the second chamber, and to the opening at the top end of the tubular shell, the secondary aperture being located at an axial height above the air flow barrier.