ATS YG excursion to Great Britain April 14th-18th 2004
Finnish Youth for Nuclear Energy, vice chairperson
had the opportunity to participate ATS YG (Finnish Nuclear Society
Young Generation) excursion to Great Britain in April 2004. I was
specifically interested in the journey, as the programme included
a thorough visit to a nuclear power productions evils
nest, Sellafield. That is a name, which makes the blood of
nuclear energy opponents coagulate.
From Manchester Airport the journey continued straight away to
Capenhurst, where Urenco fuel enrichment plant is located. On the
same area there are old plants that work based on gas diffusion.
The plants are owned by BNFL (British Nuclear Fuels), but they have
been out of service since 1982. In the plant UF6 (uranium hexafluoride)
is transformed into gaseous form and by spinning it in centrifuges
Uranium-235 and Uranium-238 are separated from each other. Heavier
U238 moves to the outer edges of the centrifuge and can therefore
be separated. The temperature gradient is maintained vertical inside
the centrifuge, which causes increase in U235-content at the lower
section. The centrifuges have magnetic bearings, because no other
mechanical structure could bear such a speed of rotational motion.
After the enrichment uranium hexafluoride is converted into uranium
dioxide (UO2). Finally, ceramic fuel is compressed into pellets,
which are grouped in zircon pipes. The technique used by BNFL is
the most environmental friendly of current techniques.
The plant is not large, because it manages only one work phase
and the pressurized tanks are taken elsewhere to be used in fuel
production. The plant employs 500 people. The functioning of it
helped to make clear why huge electricity wires are lead to the
plant: the process consumes loads of electricity. On our way there
I thought that the electricity comes from the plant.
On the second day we travelled to Springfields, where nuclear fuel
is being produced for Magnox-, AGR- (Advanced Gas-Cooled Reactor)
and some pressure water reactors. The process itself is multi-phased
and difficult to understand. However, it was awesome to watch from
one meter distance, as the loader loads fuel elements into AGR-capsules
with his woollen gloves. AGR is a British reactor type. Fifteen
reactors of that kind have been constructed since 1963, all of which
are operated by British Energy.
In Springsfield there is also development work made, which was
introduced us in the laboratories. BNFL is responsible for an international
project, which aims at developing a so called High Temperature Gas-Cooled
Modular Reactor (HTGMR). It involves using TRISO-particles (tristructual
isotrophic) in an HTGR-reactor (High Temperature Gas-Cooled Reactor).
The nucleus of TRISO-particles consists of low-enriched uranium
dioxide (UO2). The other options are thorium or plutonium, of which
the latter would probably interest the nuclear weapon states. TRISO-particles
are found in fuel elements, which are typically spherical and 6
centimetres in diameter. The uppermost shell of it is a half-centimetre
graphite layer, which covers the actual fuel matrix. That too is
graphite and includes TRISO-particles.
Considering radiation safety, the HTGMR-reactors are safe and cost-effective
to operate. However, considering safety, high temperature and vast
amount of graphite in the nucleus set their own demands to the maintenance
of a plant. Other good features are easy adjustability of power
and effortless nuclear waste disposal. Therefore, for us in Finland
it is useful to keep up with the course of events in this sector
as well, because we already have comprehensive district heating
systems in our towns.
Sellafield is quite a Disneyland for people involved in nuclear
energy. Almost everything related to fuel life-span can be found
there, apparently activities related to military purposes as well.
Great Britain has been sued to Court of Justice of the European
Communities, because inspectors have not been permitted to go everywhere
in the Sellafield area. The area employs as many as 11,000 people.
First we got to visit Calder Hall, which is the first nuclear power
plant in commercial use. In the Soviet Union, Obninsk (107 kilometres
from Moscow), there was an operating plant before that, but as the
society based on real socialism did not have markets, the plant
was not in commercial use either. Later Obninsk has become a real
Silicon Valley of Russia, as after the nuclear physicists several
IT-professionals and the most important international companies
have become aware of it. Earlier its main product and the top secret
were nuclear reactors used in submarines.
In 1953, it was Winston Churchill himself, who made the decision
about building the first four reactors in Calder Hall. Three years
later, October 17th 1956 its first reactor was inaugurated by Queen
Elizabeth II. The reactors were of the first generation Magnox-type
and gas-cooled. Carbon dioxide works as a cooler in them and graphite
as moderator. Natural uranium packed in magnesium shells is used
as fuel. Hot gas boils water in steamers and the steam in secondary
circuit rotates the generators.
There have been altogether 26 Magnox-reactors, of which 18 are
still in use. They are located in seven separate plant locations.
Reactors were also built to Latin in Italy and Tokaimura in Japan,
but those reactors are not operational any more. In Calder Hall
one can concretely understand that nuclear power production cannot
be paralysed via computer viruses, as the production is fully manual.
The interior reminds us of the good old James Bond films,
because the cranes and generators are pink, light yellow and blue.
The finest of Sellafields (earlier Windscale) plants is the
THORP (Thermal Oxide Reprocessing Plant), which was completed in
1992 and licensed in 1997. The premises with electric glass doors
were excellent indeed. In THORP it is possible to get closest to
high-active waste considering peacetime security provisions. We
were standing on lids, under which there is 1.5 metres concrete
capsule that isolates powerful radiation, but one can still feel
the warmth when touching the lids. The plant also produces so-called
MOX-fuel (Mixed Oxide Fuel). MOX-fuel includes 5 percent plutonium
generated in the reactor, which can also be exploited. Since 1963,
400 tons of MOX-fuel has been safely loaded into licensed reactors.
In Europe there are over thirty reactors of that kind. In reprocessing
some gas and fluid waste that are difficult to manage are also generated.
At its best there have been seven operational plants in the area,
but now there is only one. Instead, nuclear material is shipped
to be reprocessed in Sellafield from all over the world. Naturally
the area has an own harbour in the Irish Sea, so it is no use planning
sabotaging railway- or highway transportations! The material is
so expensive that it is shipped all the way from Japan to Sellafield.
Therefore, reprocessing does not seem very profitable financially,
although it is technically well-working and safe.
Museum is responsible for the Sellafield Visitors centres
operation: information is thus spread by an independent organisation.
The Sparking Reaction animation, which is targeted mainly
to elementary school pupils, made it clear which form of energy
one should support in modern world. There were stuff from the whole
history of nuclear energy on display in the Visitors Centre, and
a rather naive Tshernobyl -control room, in which an unstable reactor
could somehow be kept on track by pressing different buttons. If
one did not press the buttons on a regular basis, the reactor went
critical. In Western countries that reactor type could not have
even been licensed at 60s, although Greenpeace and its various
partners have repeatedly and mistakenly so claimed.