RADIATION SHIELDING
Putting Safety First

Containers for radioactive material are designed to protect those working nearby from hazardous radiation.

In the 1930s Eugene Wigner devised a formula indicating that some materials are more effective than others in absorbing, or slowing down, neutron radiation. This work established the basis for radiation-shielding studies.

By 1951, under Everitt Blizard's guidance, ORNL became a world leader in performing calculations to determine the thicknesses and configurations of lead, steel, and concrete shielding necessary to protect people and equipment from exposure to hazardous radiation levels. For the later-aborted nuclear aircraft project, ORNL researchers worked to identify lightweight shielding materials that would protect the crew of an airplane powered by a small nuclear reactor from radiation. To provide data for this effort, the ORNL Bulk Shielding Reactor and Tower Shielding Facility were built in the 1950s.

In 1958 ORNL researchers developed a neutron transport code and photon transport code to predict which shielding configurations best protect humans from neutrons and gamma rays. In 1959 they evaluated the effectiveness of reactor shielding proposed for the Savannah, the nation's first and only nuclear-powered civilian ship.

In 1966 the Oak Ridge Electron Linear Accelerator began providing data for shielding-code developers on how radiation interacts with individual atoms within the shield material. The accelerator helps scientists answer questions such as "How much neutron radiation is captured by or scattered off the atom's nucleus?" and "How much causes the atom to fission?"

In 1967 ORNL developed a computational simulation code still used today to evaluate the effectiveness of radiation shielding. In 1986 the Oak Ridge Transport model was released; this first openly available radiation transport simulation code enables the solution of extremely large, complex, three-dimensional shielding problems.

ORNL shielding research is being applied to the design of the Spallation Neutron Source's target, medical radiation therapy, and homeland security projects. ORNL researchers also respond to requests for advice on difficult shielding issues.

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