Loading presentation...

Present Remotely

Send the link below via email or IM

Copy

Present to your audience

Start remote presentation

  • Invited audience members will follow you as you navigate and present
  • People invited to a presentation do not need a Prezi account
  • This link expires 10 minutes after you close the presentation
  • A maximum of 30 users can follow your presentation
  • Learn more about this feature in our knowledge base article

Do you really want to delete this prezi?

Neither you, nor the coeditors you shared it with will be able to recover it again.

DeleteCancel

Make your likes visible on Facebook?

Connect your Facebook account to Prezi and let your likes appear on your timeline.
You can change this under Settings & Account at any time.

No, thanks

Copy of Environmental Security - Nuclear Energy

No description
by

Xin Gao

on 8 May 2011

Comments (0)

Please log in to add your comment.

Report abuse

Transcript of Copy of Environmental Security - Nuclear Energy

Environmental Change
and Security: Nuclear
Power and its Effect on
the Environment Are environmental changes security issues? Resource Scarcity
- Raw materials, territory, freshwater
Environmental Degradation
- Soil erosion, deforestation, chemical
spills (or attacks)
Global Warming
Increase in population size
Natural Disasters What is nuclear energy? http://www.bbc.co.uk/schools/gcsebitesize/science/images/ph_radio05_v2.gif
What is its effect on the environment? Does not emit carbon dioxide!
Harmful, radioactive waste:
- “ These materials can remain radioactive and dangerous to
human health for thousands of years.” (US Energy
Information Administration)
- “ There is currently no permanent disposal facility in the
United States for high-level nuclear waste. High-level waste
is being stored at nuclear plants.” (US Energy Information
Administration)
What happens when natural disaster strikes? Japan, 2011... What exactly happened in Japan? Cooling system failed, causing pressure to rise, which caused the leak of radioactive vapor.
Hourly radiation release following the leak: 1,015 microsieverts (not healthy for ONE person in a YEAR)
As of the day after, all those within a 20 mile radius were evacuated.
Nuclear energy is the energy that holds atoms together. The nuclear energy we use is harvested when atoms are split.
To produce nuclear energy, we use a nonrenewable and relatively rare resource: Uranium. Japan Today: Level 7 - Major Accident - Major release of radio­active ­material with widespread health and environmental effects requiring implementation of planned and extended­countermeasures (International Nuclear and Radiological Event Scale (INES) introduced by the IAEA). So how does this relate to us? Policy Question: Given the recent disaster in Japan, should the United States continue to pursue nuclear energy? Policy 1 The US should continue to research, develop and increase the amount of energy provided by nuclear power. Japan needs to import roughly 80% of its energy requirements.
Its first commercial nuclear power reactor began operating in mid 1966, and nuclear energy has been a national strategic priority since 1973.
The country's 50 main reactors provide some 30% of the country's electricity and this is expected to increase to at least 40% by 2017.
Japan has a full fuel cycle set-up, including enrichment and reprocessing of used fuel for recycle.
(http://www.world-nuclear.org/info/inf79.html) Japan: a unique situation What really happened? "Without question, the accident at Chernobyl was the result of a fatal combination of ignorance and complacency. "As members of a select scientific panel convened immediately after the...accident," writes Bethe, "my colleagues and I established that the Chernobyl disaster tells us about the deficiencies of the Soviet political and administrative system rather than about problems with nuclear power."" Chernobyl "The experimenters allowed this dangerous condition to develop even though they had deliberately bypassed and disconnected every important safety system, including the emergency core-cooling system. They had also disconnected every backup electrical system, down to and including diesel generators, that would have allowed them to operate the reactor controls in the event of an emergency." No commercial reactor in the United States is designed anything like the RBMK reactor. Cohen summarizes several of the differences:
1. A reactor which is unstable against a loss of water could not be licensed in the United States.
2. A reactor which is unstable against a temperature increase could not be licensed here.
3. A large power reactor without a containment [structure] could not be licensed here. Three Mile Island http://www.pbs.org/wgbh/pages/frontline/shows/reaction/readings/chernobyl.html The misreading of the core coolant pressure valve was a key contributor to the initial failure to recognize the accident as a loss-of-coolant accident, and led operators to turn off the emergency core cooling pumps, which had automatically started after the PORV stuck and core coolant loss began, due to fears the system was being overfilled.
The closure of these valves was a violation of a key NRC rule. This closure was later singled out by NRC officials as a key one, without which the course of events would have been very different. (Rogovin, Mitchell (1980). Three Mile Island: A report to the Commissioners and to the Public, Volume I. Nuclear Regulatory Commission, Special Inquiry Group.) http://www.washingtonpost.com/wp-srv/national/longterm/tmi/stories/ch1.htm The relief valve should have closed again when the excess pressure had been released, but the relief valve stuck open due to a mechanical fault. The open valve permitted coolant water to escape from the primary system, and was the principal mechanical cause of the true coolant-loss meltdown crisis that followed. Walker, J. Samuel (2004). Three Mile Island: A Nuclear Crisis in Historical Perspective. Berkeley: University of California Press There is not a single recorded death either directly from any meltdown within the reactor or even from longterm harm caused by radiation. Policy The development of nuclear power should be STOPPED Negative Impacts: US has not always properly disposed of waste
- We may have the same fate as Japan
- How do we store it? AT PLANTS
Uranium is not a renewable resource
Nuclear technology can be used for good AND bad Rods in water underground
- Vulnerable for natural disasters (EXACTLY what
happened in Japan) Above ground in “dry cask storage”
- Not permanent
- Vulnerable to us used as a weapon We should only use nuclear power until a viable alternative is found. Viable alternatives include renewable sources such as biomass, water, geothermal, wind, solar. The practice and research of clean enegies are rapdily developing. http://www.eia.doe.gov/energy_in_brief/images/charts/us_energy_consumption_by_energy_source-large.jpg Weaknesses of the policy: No, this is not the most economically friendly option.
- Safety should be more important
Renewable energy has its weaknesses.
- Solar or cloudy days, wind on calm days
MUCH more research needs to be done
3 Policy Energy Cocktail:
Nuclear power is not 100% evil, but we need to develop more green power. Problems we can't solve Source : http://www.epa.gov/greenpower/gpmarket/index.htm
Wind energy produces about 2% of the US' power.

Solar, currently produces less than 1% of the US' electricity.

Source: http://news.yahoo.com/s/ap/20110126/ap_on_bi_ge/us_obama_clean_energy Top 10 clean energy investors Investment by country and sector, 2010, billions of $ (published by the US Pew Environment Group)
Produced electricity more from solar, wind, geothermal, biogas, biomass, and low impact small hydroelectric sources. Harness Green Power 2 Provides 20% of US electricity, 75% French
China Powers Ahead in Green Technologies
http://unc.news21.com/index.php/state-by-state-energy-cocktails.html Alternatives are less viable. Predictions indicate that by the year 2050, the US will have to increase our power supply by almost 100% of our current levels.
Experts also believe that the US is roughly 67% over target carbon emissions. http://unc.news21.com/cocktail/cocktail.html# Therefore, the US needs a source of energy that is both economically viable and
environmentally friendly. -Fuels like coal and oil are very cheap to burn, but are extremely dirty.
-Sources like wind and solar power and very clean, but are inefficient and very
costly to develop and to integrate into the infrastructure. The solution is nuclear energy. Scientists are developing and researching new
methods that both dramatically increase the safety and reduce the radioactive
waste of nuclear power plants. There are many new types of nuclear technology currently being developed.
Two major developments are the use of "pebbles" and of an element called thorium.
New types of reactors include a super-critical water reactor (SCRW), a molten-salt reactor (MSR), and a hydrogen moderated self-regulating nuclear power module (HPM). Advantages
The higher temperatures and use of a supercritical Brayton cycle improves efficiency (~45% versus ~33% of current LWRs)
The higher efficiency means better fuel economy and a lighter fuel load, so residual (decay) heat would be less
Supercritical water has excellent heat transfer, allowing high power density, a small core and a small containment structure
An SCWR is a lot simpler, making it cheaper and more reliable
Water is liquid at room temperature, cheap, non-toxic and transparent, simplifying inspection and repair (compared to liquid metal cooled reactors)
A fast SCWR can be a breeder reactor, and also burn the long-lived actinide isotopes
A heavy-water SCWR can breed fuel from thorium (4x more abundant than uranium), with increased proliferation resistance over plutonium breeders
Challenges
Extensive material development and research on supercritical water chemistry under radiation
Special start-up procedures needed to avoid instability before the water reaches supercritical conditions
Supercritical water expands more than liquid water when heated, so an SCWR can be less stable than a PWR (but more than a BWR)
A fast SCWR needs a relatively complex reactor core to have a negative void coefficient Super-Critical Water Reactor http://nuclear.inl.gov/gen4/docs/scwr_annual_progress_report_gen-iv_fy-03.pdf Advantages
It is safe to operate and maintain: Molten fluoride salts are mechanically and chemically stable at sea-level pressures at intense heats and radioactivity
There is no high pressure steam in the core, just low-pressure molten salt. This means that the MSR's core cannot have a steam explosion, and does not need the most expensive item in a light water reactor, a high-pressure steam vessel for the core.
The thorium breeder reactor uses low-energy thermal neutrons, similarly to light water reactors. It is therefore much safer than fast-neutron breeder reactors that the uranium-to-plutonium fuel cycle requires. The thorium fuel cycle therefore combines safe reactors, a long-term source of abundant fuel, and no need for expensive fuel-enrichment facilities.
MSRs work in small sizes, as well as large, so a utility could easily build several small reactors
Molten salt fuel reactors are not experimental. Several have been constructed and operated at 650 °C temperatures for extended times, with simple, practical validated designs. There is no need for new science and very little risk in engineering new, larger or modular designs
Disadvantage
Fluoride salts naturally produce hydrofluoric acid when in contact with moisture, which may lead to release of fumes under catastrophic circumstances. Although this would be taken into consideration in the reactor's design and shutdown/decommission processes, this hazard would need to be addressed in unforeseen emergency situations that compromise the reactor's integrity. Molten-Salt Reactor http://www.ornl.gov/~webworks/cppr/y2001/pres/120507.pdf Hydrogen Moderated Self-regulating Nuclear Power Module Inherently safe - self moderating
- With this design, a meltdown is impossible. This design uses
uranium hydride, which is both a fuel and a neutron
moderator. At high temperatures it decomposes into
hydrogen gas and uranium metal.
Easy to service
Intended to be buried and refueled every 7-10 years
Costs are projected to be comptetive with fuels like coal and natural gas (Cheap!) http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1&p=1&f=G&l=50&d=PG01&S1=20100119027.PGNR.&OS=DN/20100119027&RS=DN/20100119027 http://www.neimagazine.com/story.asp?sectionCode=76&storyCode=2054285 Pebble-Bed Reactors "Pebble Bed Reactors offer a future for new nuclear energy plants. They are small, modular, inherently safe, flexible in design and operation, use a demonstrated nuclear technology and can be competitive with fossil fuels. Pebble bed reactors are helium cooled reactors that use small tennis ball size fuel balls consisting of only 9 grams of uranium per pebble to provide a low power density reactor. The low power density and large graphite core provide inherent safety features such that the peak temperature reached even under the complete loss of coolant accident without any active emergency core cooling system is significantly below the temperature that the fuel melts." http://web.mit.edu/pebble-bed/papers1_files/PBReactors.pdf Thorium: Safe and Abundant Thorium is up to four times as abundant as fissile uranium.
Thorium can be used as a fuel by breeding it to fissile U-233.
Waste from spent thorium is less radioactive and therefore much safer.
Because thorium is less radioactive, it greatly reduces proliferation risks. http://www.world-nuclear.org/info/inf62.html
Full transcript