TRANSPORTATION OF RADIOACTIVE MATERIALS - Environmentally Conscious Materials Handling - page 227

of the material being transported, and population distribution along the route.
It calculates doses to people living along the route, people traveling along the
same route—both in the same direction as the shipment and in the opposite
direction—and the crew transporting the used fuel.
The Department of Transportation also regulates the labeling of shipments
of radioactive materials, including used nuclear fuel and HLW. There are three
levels of labels used for packages containing radioactive materials, with the
level of the label being determined by the maximum dose at any point on the
surface of the cask. White- I label is used if the surface dose is less than 0.5
millirem/hour (mrem/hr). Yellow-II label is used if the surface dose is between
0.5 mrem/hr and 50mrem/hr, and Yellow-III is used if the dose is greater than
50 mrem/hr but less than 200 mrem/hr or if the material being shipped is a
“highway route controlled quantity” (49 CFR 172). Used nuclear fuel and HLW
are referred to as “highway route controlled quantities,” and shipments must carry
the Yellow-III label even though the dose from a shipping cask loaded with used
nuclear fuel must be no more than 10 mrem/hr at 2 meters from the cask surface
(49 CFR 172).
Finally, drivers of trucks transporting radioactive materials must typically meet
several requirements. No specific requirements have yet been set for drivers of
trucks loaded with used nuclear fuel. However, the Department of Energy has
published requirements for drivers of trucks carrying shipments to the Waste
Isolation Pilot Plant, a disposal site for transuranic waste (a type of radioac-
tive waste) near Carlsbad, New Mexico. Those requirements include experience
(minimum of 325,000 miles driven in the past five years), a stringent background
check, and taking and passing over 20 training programs on topics related to safe
handling and transportation of radioactive materials.

6 TRANSPORTATION CASKS FOR USED NUCLEAR

FUEL AND HLW
This section describes the factors that must be considered when designing a cask
for transporting used nuclear fuel or high-level waste, the process for licensing
those casks, and the tests the casks must pass in order to receive a certificate of
compliance. Some casks for transporting used nuclear fuel do exist, have received
certificates of compliance, and have been used to transport used nuclear fuel in
the United States. Information on those casks and their current status will be
provided.
Figure 8.6 is an illustration of a generic truck cask for shipping used nuclear
fuel. A truck cask typically weighs about 50,000 pounds and is about 4 feet
in diameter and 20 feet long. Its cargo, usually one to nine used nuclear fuel
assemblies, is contained in the inner basket, which holds the fuel assemblies
firmly in place during transportation. The cask has inner and outer steel shells
with a layer of lead between them. The steel provides structural strength, while