Bernard White
Senior Project Manager 
The NAC LWT transport package Photo courtesy of NAC International
In September 2013,
we talked about transportation of spent nuclear fuel and how we know it
is safe. This month, we want to discuss the safety basis for
transporting other types of radioactive material.
The
NRC recently approved a package to transport high enriched uranyl
nitrate. This material is left over from the production of medical
isotopes used in millions of diagnostic procedures every year. This
package is to be used to bring material currently stored in Canada,
where the isotopes were made, to the Savannah River site in South
Carolina. The shipments are part of a DOE program to take back high
enriched uranium from countries to which the U.S. supplied it.
Our
review did not address whether the shipment should be made. Nor is it
specific to any route. It just looked at whether the proposed shipping
package design meets our requirements for safe transport. We rigorously
reviewed the information submitted by the cask designer, NAC
International. We asked four sets of detailed questions and thoroughly
reviewed the applicant’s responses. After two years of review and two
face-to-face meetings, we have answers to all our questions and we’re
satisfied that the package design meets all NRC requirements for safe
transport.
The
high enriched uranyl nitrate, which is a liquid, will be transported
using special containers that were designed to prevent leakage. To
ensure they do not leak, the containers are leak tested after
fabrication and prior to transport, each time the container is filled.
These containers must also be replaced once they have been in use for 15
months. Together, these requirements give the NRC confidence that the
containers will not leak.
These
leak-tight containers will be placed into specially-designed packages
for transport. This package design has been used for 25 years to safely
transport a wide variety of radioactive materials. The inner containers
and the outer packaging together make up the transport package.
Our
review of this transport package design gives us confidence that, even
if there were to be a transport accident, radioactive material will not
leak from the package; dose rates will not be high enough to cause harm
to anyone; and a nuclear chain reaction will not occur. Packages are
evaluated for conditions that mirror normal transportation as well as
the forces the package may experience in a severe accident.
The
conditions assessed for routine transport include rain, hot and cold
temperatures, a drop that may occur during handling, and the vibration
that we all feel in a car or riding on a train.
For
accident conditions, the package must be shown to be able to withstand
forces that are more severe than in a real-world accident. This is done
by testing or evaluating the package in a sequence of stringent tests.
We discussed these tests in detail in our September 2013 blog.
This
package has been shown to be able to safely transport contents that are
much heavier and more radioactive than the high enriched uranyl
nitrate, including spent nuclear fuel. The dose rates from the package
containing liquid uranyl nitrate will be much lower than when the
package is loaded with spent fuel.
For
all these reasons, the NRC Is confident the package design meets all
our requirements for safe transport. We follow the same review process
for every transport package design we receive. In every case, we make
sure we thoroughly understand the design and all the analyses in the
application. We ask questions, if necessary, and often perform our own
analysis. In some cases, including this one, we impose special
conditions to give added assurance of safety. Only when we are satisfied
a design meets every NRC requirement will we issue an approval.
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Michele Kearney's Nuclear Wire - Major Energy and Environmental News and Commentary affecting the Nuclear Industry. Nuclear Activities
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