CHM333:

Containers used for Transportation of Nuclear Wastes

Picture of a nuclear storage cask to be used for transportation to Yucca Mountain. Source

One of the most important aspects of nuclear waste transportation from one site to the next is the container that is carrying the waste. The waste storage container must be very strong and able to withstand any number of possible accidents. From car crashes to explosions, these containers must be break resistant, so in the event of an emergency, there is no leakage of radioactive waste. This section will summarize two aspects of nuclear waste containers: the conditions under which they are certified and the specifications for casks that will be used to transport nuclear materials to the Yucca Mountain repository.

Nuclear Regulatory Commission Certification

Any cask that is to carry nuclear waste must pass a series of puncture, fire, and impact tests to be certified by the Nuclear Regulatory Commission (NRC). These tests are as follows:

· Survive a 9 meter drop onto an unyielding surface
· Puncture test entailing a 1 meter drop onto a steel rod 16 centimeters in diameter
· Survive 30 minutes in an all engulfing, 800 degree F fire
· Be immersed under 0.9 meters under water
· For casks carrying spent fuel: must survive a 1 hour immersion under 200 meters of water.

If a cask is to transport nuclear waste, it must first pass these stringent tests.1

Specifications for Casks Traveling to Yucca Mountain

If casks begin to be transported to Yucca Mountain, nuclear waste will, in some cases, travel farther than it has ever traveled before. This is why the containers carrying waste to Yucca Mountain must be especially strong.

There will basically be two designs for casks transporting nuclear waste to Yucca Mountain: cask for transportation by railroad, and casks for truck transportation. These casks are all designed based on what type of fuel they are carrying. An example of this is a cask that would be carrying nuclear spent fuel. Commercial spent nuclear fuel casks are designed to lie horizontally while being shipped. They will be 4.6 to 6 meters long and 0.5 to 2 meters in diameter. For truck, these casks typically weigh 21 to 22 metric tons when empty and 22 to 24 metric tons when full. For trains, casks carrying nuclear spent fuel typically weigh 59 to 91 tons when empty and 64 to 110 metric tons when full.

A cask carrying nuclear spent fuel will be constructed of cylindrically formed stainless steel or carbon steel plate materials. These cylinders would be assembled to form and inner and outer cylinder. A liner made of depleted uranium or lead will be placed between the two stainless steel or carbon steel cylinders. A vessel bottom with depleted uranium or lead between the two cylinders will be welded to the cylinders. Finally, a polypropylene sheath would be placed along the outside of the cask for neutron shielding, while a neutron absorbing material may be welded on the inner liner if necessary. Once the cask is filled with waste, a lead or depleted uranium cover is placed over the top of the cylinder and is closed and sealed with bolts.2