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1. MOVEMENTS AND RISKS
IN THE TRANSPORT SECTOR
1.1 The diversity of radioactive
substance transport movements
The regulations place these packages in different risk
“classes”. Class 1, for example, represents explosive
materials and objects, class 3 flammable liquids, and
class 6 toxic and infectious materials. Class 7 covers
hazardous radioactivematerial. About 770,000 shipments
of radioactive substances are transported each year in
France. This represents about 980,000 packages of
radioactive substances, or just a few percent of the total
number of dangerous goods packages transported each
year in France.
The fuel cycle necessitates an estimated annual total of
19,000 shipments involving 114,000 packages. These
include approximately:
•
2,000 shipments fromor to foreign countries or transiting
via France, representing about 58,000packages shipped;
•
389 shipments of new uranium-based fuel and some
50 shipments of new uranium and plutonium-based
“MOX” fuel;
•
220 shipments transporting spent fuel from the
nuclear power plants operated by EDF to the La Hague
reprocessing plant operated by Areva;
•
about 100 shipments of plutonium in oxide form
transported from the LaHague reprocessing plant to the
MELOX fuel production plant in the Gard département;
•
250 shipments of uranium(UF
6
) hexafluoride necessary
for the fuel manufacturing cycle.
1.2 Risks associated with
the transport of radioactive
substances
The content of the packages is highly diverse: their level
of radioactivity varies over more than fifteen orders of
magnitude, that is to say froma few thousand becquerels
for low-level pharmaceutical packages, to quadrillions
(billions of billions) of becquerels for spent fuel. The
weight of the packages also varies froma fewkilogrammes
to about a hundred tonnes.
The major risks involved in the transport of radioactive
substances are:
•
the risk of external irradiation of persons in the event of
damage to the “biological protection” of the packages,
a technical material that reduces the radiation received
through contact with the package;
•
the risk of inhalation or ingestion of radioactive particles
in the event of release of radioactive substances;
•
contamination of the environment in the event of release
of radioactive substances;
•
the starting of an uncontrolled nuclear chain reaction
(“criticality safety” risk) that can cause serious irradiation
of persons if water is present and the safety of fissile
radioactive substances is not controlled.
Moreover, the radioactive substances can also be toxic and
corrosive. This, for example, is the case with shipments
of natural uranium with low radioactivity, for which
the major risk for man is the chemical nature of the
compound, especially if it is ingested. Similarly, uranium
hexafluoride, used in themanufacture of fuels for nuclear
power plants can, in the case of release and contact with
water, formhydrofluoric acid, a powerful corrosive and
decalcifying agent.
Catering for these risks implies having full control over
the behaviour of the packages to avoid any release of
material and deterioration of the package protection in
the event of:
•
fire;
•
physical impact further to a transport accident;
•
ingress of water into the packaging, as water facilitates
nuclear chain reactions in the presence of fissile
substances;
•
chemical interaction between the various constituents
of the package;
•
substantial release of heat from the transported
substances, to avoid possible heat damage to the package
constituent materials.
This approachmeans that safety principlesmust be defined
for the transport of radioactive substances:
•
safety is based first and foremost on the robustness of the
package: regulatory tests and safety demonstrations are
required by the regulations to prove that the packages
can withstand reference accidents;
T
he transport
of radioactive substances is a specific sector of dangerous goods
transport characterised by the risks associated with radioactivity.
The scope of regulation of the safety of radioactive substance transport covers
various fields of activity in the industrial, medical and research sectors. It is based
on stringent and restrictive international regulations.
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CHAPTER 11:
TRANSPORT OF RADIOACTIVE SUBSTANCES
ASN report on the state of nuclear safety and radiation protection in France in 2015