What are back end materials?
The nuclear fuel cycle can be broken down into what is generally
known as the 'front end' and 'back end' operations. The front end
covers the operations from the mining of uranium to the manufacture
of fuel assemblies for loading into the reactors. The back end
covers the operations concerned with spent fuel that leaves
reactors.
Fuel used in a nuclear power plant generates electricity for
about five years. After this time it becomes less efficient and
needs to be replaced. This spent fuel still contains 96% of the
original uranium, 1% of plutonium, and also about 3% of fission
waste products. At this stage, spent fuel can either be sent for
storage pending final disposal, or reprocessed to recover the
uranium and plutonium.
The reusable uranium and plutonium can be used to produce new fuel
such as Mixed Oxide (MOX) fuel. The 3% waste is transformed into a
solid, insoluble glass form by a vitrification process and stored
pending final disposal, for instance into a deep geological
repository.
Spent fuel
Spent nuclear fuel is intensely radioactive. It is transferred
first from the reactor to the on-site storage ponds for shielding
and to allow radioactivity to decay. For subsequent transport off
the reactor site, either to off-site storage or to reprocessing
facilities at home or abroad, it is transported in high-integrity
packages, known as casks. These casks are massively constructed
from steel weighing typically around 100 tonnes.
Spent fuel is transported extensively by rail across Western
Europe and also by sea in Sweden, and from the Far East to
reprocessing plants in France and the UK. Sea transport is by
specialist ships designed and operated according to the Irradiated
Nuclear Fuel (INF) Code of the International Maritime Organization
(IMO).
Vitrified high-level waste
Vitrified high-level waste from the reprocessing of spent fuel
is stored temporarily at the reprocessing plant to allow fission
product heating to decay before it is returned to the country of
origin. The transport casks are similar in design and construction
to those for spent fuel and the transport operations whether by
rail or sea also are similar. Several sea and rail shipments of
vitrified waste have been successfully carried out.
Mixed oxide fuel (MOX fuel)
The plutonium derived from the commercial reprocessing of spent
fuel is normally returned to the country of origin in the form of
new mixed plutonium/uranium oxide fuel (MOX fuel) elements in which
the enriched uranium isotope is replaced by plutonium. They are
transported under special conditions by road or rail and in
specialist vessels for sea transport. Extensive experience in MOX
transport has been built up in Western Europe over many years and
recently also by sea from Europe to the Far East. MOX fuel has been
safely generating electricity in nuclear power plants around the
world since the 1960s.
Specialised transport companies
Experienced and specialised companies have safely and securely
transported back end materials on an industrial scale for over 45
years. These companies have developed transport systems and
carefully manage back end transports around the world following
required safety procedures. Comprehensive emergency response plans
are in place, incorporating emergency arrangements for all modes of
transport. These plans are routinely tested to ensure that public
health and the environment are well protected in the event of an
incident.