accounted for just 11% of the worlds electricity production in 2014 yet nuclear
reactors emit zero greenhouse gases and is around 8000 times more efficient
than fossil fuels, which generated 62% of the worlds electricity in 2014. Nuclear
power is also more reliable than other finite sources as there is enough
Uranium to last 70-80 years. Power plants can also run interrupted for over a year
and production is not dependent on the climate. Considering global warming is a
pressing issue and the recent Paris agreement one would assume that nuclear
power would increase but that is not the case. Taking all this into account
there must be other reasons for nuclear power not being the most common way to
generate electricity. The biggest issue linked with nuclear power is waste.
Nuclear waste is so difficult to deal with due to how long it remains
There are 5 main types
of nuclear waste. The first being naturally occurring radionuclides which are
rejected during the mining, milling and refining of fuel. Actinides are formed
from neutron absorption in the fuel rods of the reactors. Fission products from
the fission of Uranium and Plutonium in the fuel rods forming lighter nuclides.
Solid radionuclides are also formed when neutrons are absorbed by the reactor
structure forming isotopes like iron-59 and cobalt-60. Finally, gaseous and liquid
radionuclides are formed by neutron absorption in and around the reactor these
Waste from the mining
process causes little harm as it normally has a low radioactivity and so is
disposed normally. The slurry produced in the milling process contains all the
uranium daughter products and about 1 gram per 1000 tonnes of tailings. So,
there would be 300g of radium 226 present in the waste for every 1000 tonnes of
uranium produced. The slurry is stored in a basin where solids stay behind a
dam and liquid overflows to a waste treatment lagoon. The radium is then
precipitated out with barium sulfate and the remaining liquid is then drained
and discharged into natural water systems.
During the refining process,
most waste is again low in radioactivity and normally handled on site. Hexafluoride
is used to refine the uranium that was mined, calcium fluoride ash is produced
and is drummed and buried in a suitable place. Refinery’s often have large
quantities of liquid waste which is stored in ponds and the radioactive sludges
are stored underground.
Irradiated fuel still
contains fissile uranium 235 and plutonium 239 but must first be chemically separate
before it can be reused. The neutron absorbing fission products must be removed
from the fuel. The fuel is reprocessed by dissolving the uranium oxide in nitric
acid and extracting the uranium and plutonium through solvent extraction. This
process produces waste in the form of the metal fuel cladding and an acidic
solution containing actinides and fission products. The acidic solution is
highly radioactive and is currently concentrated, neutralised and then stored
in large tanks. The irradiated fuel that is not reprocessed has radioactive
properties that are governed by the fission products for the first 100 years
and then the actinides.
The by-products of
nuclear fission have long half-lives so they remain hazardous for thousands of
years. According to the EPA uranium 235 has a half-life of 703.8 million years.
So, the waste will remain volatile for centuries, this makes it difficult to
store as all current option are not suited for long term situations. Long half-lives
also make nuclear waste attractive to terrorists who can target the storage
facilities to cause mass damage. Safeguards have to be implemented to prevent
the uranium and plutonium being used in the production of weapons.
Radiation exposure can
cause long-term health problems including gastrointestinal diseases,
cardiovascular diseases and cancers. If the waste was managed incorrectly it
can quickly contaminate the surrounding area. It was discovered that leukaemia diagnoses
in Belarus, Ukraine and Russia had increased by 50% after the Chernobyl
accident between 1990 and 2000. An example of this would be the Asse salt mine
in Germany. More than 120,000 barrels of low level to intermediate level waste
was stored there between 1967 and 1978, many of which are said to be leaking. The
mine has displayed structural issues and so the waste needs to be moved. The
German Federal Office for Radiation Protection concluded that the risk of
groundwater contamination was large and so the containers must be retrieved.
Nuclear waste also
raises lots of ethical issues. Due to the longevity of the hazardous waste, management
strategies need to take into account future generations and so
intergenerational equity must be achieved in order for nuclear to be
sustainable. It must not be a burden passed on to the future.
Public perception of
nuclear waste has a great effect on how it is dealt with. Communities will
often be very reluctant to house a nuclear waste repository, halting any
progress that could be made for more sustainable storage solutions.