Nuc
hazard!
The environmental impact of nuclear power results
from the nuclear fuel cycle, operation, and the
effects of nuclear accidents.
The routine health risks and greenhouse gas
emissions from nuclear fission power are [??]
small relative to those associated with coal, oil
and gas and
comparable to hydro power.
As with hydro power, there is a "catastrophic
risk" potential if containment fails,
which in nuclear reactors can be brought about
by
- over-heated fuels melting and
- releasing large quantities of fission products
into the environment.
• The public is sensitive to these risks and there
has been considerable public opposition to
nuclear power.
• Ended the rapid growth of global nuc power
capacity – why?
– The 1979, Three Mile Island accident and
– 1986, Chernobyl disaster,
– along with high construction costs.
• A further disastrous release of radioactive
materials followed the 2011 Japanese tsunami
which damaged the Fukushima Nuclear Power
Plant,
- resulting in hydrogen gas explosions and
- partial meltdowns classified as a Level 7
event.
• The large scale release of radioactivity
resulted in people being evacuated from a 20
km exclusion zone set up around the power
plant, similar to the 30 km radius Chernobyl
Exclusion Zone still in effect.
Waste streams
Nuclear power has at least 4 waste streams that
may harm the environment:
1. spent nuclear fuel [used nuc fuel] at the
reactor site (including plutonium waste)
2. tailings and waste rock at uranium mines and
mills
…
3. releases of small amounts of radioactive
isotopes during reactor operation
4. releases of large quantities of dangerous
radioactive materials during accidents
The nuclear fuel cycle involves some of the most
dangerous elements and isotopes known to
humankind, including
- more than 100 dangerous radio-nuclides and
- carcinogens such as strontium-90, iodine-131
and cesium-137, which are the same toxins
found in the fall out of nuclear weapons.
Levels …
i. Low-level waste
ii. Midiii. HighBronze/Silver/Gold/Platinum!
i. Low-level waste - LLW
• It is generated from hospitals and industry, as
well as the nuclear fuel cycle.
~ include
–
–
–
–
–
–
paper,
rags,
tools,
clothing,
filters, and
other materials which contain small amounts of
mostly short-lived radioactivity.
• Materials that originate from any region of an
Active Area are commonly designated as LLW
as a precautionary measure, even if there is
only a remote possibility of being
contaminated with radioactive materials.
• Some high-activity LLW requires shielding
during handling and transport
• But most LLW is suitable for shallow land
burial.
• To reduce its volume, it is often compacted or
incinerated [burnt/cremated] before disposal.
• Low-level waste is divided into four classes:
class A, class B, class C, and Greater Than Class
C (GTCC).
ii. Intermediate-level waste
• It contains higher amounts of radioactivity and in
some cases requires shielding.
~ includes
– resins[?],
– chemical sludge [liquid waste or sewage discharged
into a river or the sea] and
– metal reactor nuclear fuel cladding shell, shield,
protective clothing], as well as
– contaminated materials from reactor
decommissioning.
Nuclear decommissioning
• OSD!
• Nuclear decommissioning is the dismantling
and decontamination of a nuclear power plant
site
so that it will no longer require measures for
radiation protection.
Read – related history
• It may be solidified in concrete or bitumen for
disposal.
• As a general rule, short-lived waste (mainly nonfuel materials from reactors) is buried in shallow
repositories,
while long-lived waste (from fuel and fuel
reprocessing) is deposited in geological
repository.
• U.S. regulations do not define this category of
waste; the term is used in Europe and elsewhere.
Deeeeeep repository
• A deep geological repository is a nuclear
waste repository  excavated deep within a
stable geologic environment (typically below
300 m or 1000 feet).
• It entails a combination of waste form, waste
package, engineered seals and geology that is
suited to provide
– a high level of long-term isolation and
– containment without future maintenance.
The International Panel on Fissile Materials has
said:
• It is widely accepted that spent nuclear fuel
and high-level reprocessing and plutonium
wastes require well-designed storage for
periods ranging from tens of thousands to a
million years, to minimize releases of the
contained radioactivity into the environment…
• …
• Safeguards are also required to ensure that
neither plutonium nor highly enriched
uranium is diverted to weapon use.
• There is general agreement that placing spent
nuclear fuel in repositories hundreds of
meters below the surface would be safer than
indefinite storage of spent fuel on the surface.
iii. High-level waste
• It is produced by nuclear reactors.
• It contains fission products and transuranic
elements generated in the reactor core.
• It is highly radioactive and often hot.
• It accounts for over 95% of the total
radioactivity produced in the process of
nuclear electricity generation.
• The amount of HLW worldwide is currently
increasing by about 12,000 metric tons every
year, which is the equivalent to about 100
double-decker buses or a two-story structure
with a footprint the size of a basketball court.
• A 1000-MW nuclear power plant produces
about 27 tonnes of spent nuclear fuel
(unreprocessed) every year.
Transuranic waste
• Elements that have an atomic number greater
than uranium are called transuranic ("beyond
uranium").
• Because of their long half-lives, TRUW is
disposed more cautiously than either low- or
intermediate-level waste.
Ways of disposal?
In second half of 20th century, several methods of
disposal of radioactive waste were investigated
by nuclear nations, e.g.,
• "Long term above ground storage", not
implemented.
• "Disposal in outer space", not implemented.
• "Deep borehole disposal", not implemented.
• "Rock-melting", not implemented.
• "Disposal at subduction zones", not
implemented.
• "Ocean disposal", done by USSR, UK,
Switzerland, USA, Belgium, France, The
Netherlands, Japan, Sweden, Russia, Germany,
Italy and South Korea. (1954–93)
– It's not permitted by international agreements.
• "Sub seabed disposal", not implemented, not
permitted by international agreements.
• "Disposal in ice sheets", rejected in Antarctic
Treaty
• "Direct injection", done by USSR and USA.
International radioactive waste hazard
symbol featuring the trefoil design
• Authorities in Italy are investigating
a 'Ndrangheta mafia clan accused of
trafficking and illegally dumping nuclear
waste.