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 wasteii. Mid-iii. High-

Bronze/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 non-fuel 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.