METALS IN MEDICINE AND THE ENVIRONMENT

Nuclear power has the ability to produce energy without releasing harmful greenhouse gas emissions into the atmosphere.  However, the energy source is also dangerous because it produces radioactive waste that has to be sequestered from the environment for 10,000 years, so as not to cause harm to public health or the environment.

Introduction

Nuclear power is a relatively new energy source that is used commonly in the world and the US.  Only 20% of the electricity generated in the US comes from nuclear power.  Some countries such as France generate 77% of their electricity from nuclear power.  The diagram in Figure 1 demonstrates how a nuclear power plant works.  Electricity is generated in a nuclear power plant by harvesting the heat released when an atom such as uranium is split in half (1). 


Figure 1:  Diagram showing how a nuclear power plant works (1).


Environmental/Public Health Impacts

Although many people assert that nuclear power is an environmentally conscious energy source because no greenhouse gases are emitted, it is in no way shape or form a sustainable or renewable energy source.  Mining uranium can have similar problems that arise with coal mining with the added problem that uranium mill tailings, waste formed by extracting the uranium, are radioactive.  Only 0.1% to 0.2% of uranium ore is made up of uranium, and of that only 0.7% of this uranium is in the correct form to be used in the reactor (2).  Uranium mining because sulfuric is used to extract the uranium causes contamination to ground water from radioactive metals and other metals.  In situ leaching is particularly harmful as diagramed in Figure 2, because the rock is not removed from the ground instead sulfuric is merely pushed into a deep aquifer(3).



Figure 2: A diagram of how in situ leaching mining works. (3)

A nuclear power plant meltdown such as the one that occurred in Chernobyl caused a significant amount of radioactive material to journey through Ukraine and all of Europe.  This huge radiation exposure largely occurred because there was no containment building.  In Three Mile Island a meltdown also occurred, but most of the radiation was secured inside the containment building.  Very strict restrictions have made nuclear power plants safer.  Nuclear power plants only emit 0.009 millirems/year, which is a negligible amount compared to natural background radiation (4).  Therefore, nuclear power plants themselves are fairly safe.


However, the waste produced at the end of the process has a huge potential to cause public health problems. Two levels of waste are created at nuclear power plants: low-level waste (LLW) and high-level waste (HLW).  LLW consists of cleaning items and other materials that are exposed to radiation.  Typically, LLW is compacted and burned in special facilities and buried in the ground (2).  HLW is defined as used nuclear reactor fuel.  As shown in Figure 3, the waste takes 10,000 years before the activity begins to level off.  Developing strategies to keep this waste carefully contained for 10,000 years has been difficult, and debates over a national repository have been occurring for quite some time (2).



Figure 3:  The radioactivity of various different radioactive metals in HLW over time (2).


New Technologies

Research has shown that thorium as a fuel source has distinct advantages over uranium.  Thorium is found at a higher concentration in the earth and all thorium can be used in the reactor, so less will have to be mined.  The use of thorium rather than uranium will decrease the magnitude and radioactivity of waste.  As shown in Figure 4, the radioactivity of the waste using a typical U-Pu fuel without processing is shown by the black line.  The Th-U mixtures both produce waste substantially lower in radioactivity than this line (5).  When using thorium spent fuel cannot be used in nuclear weapons, so thorium is safer to use (6).  The use of thorium in nuclear energy is still at the beginning stages.  More research is necessary to be sure that these benefits are true.  A large scale switch to thorium from uranium might be made in the near future, but cannot be done presently.

 

Figure 4:  The radioactivity of waste over time with the use of different fuels. (5)  


Comparison of Nuclear Power to Other Energy Sources


Coal and Nuclear Power
Coal plants directly just by burning coal release 8 metric tons of carbon dioxide on average per person living in a developed country per year as shown by Figure 5 below.  Coal also releases heavy metals such as lead, selenium, uranium, fluorine, and arsenic (7).  Mercury is also released from coal plants.  Mercury accumulation in fish is having a detrimental impact on human health. Young children and pregnant mothers are advised not to consume certain types of fish because of the mercury content.  The mercury content is only increasing and cannot be easily removed from the environment (8).  The heavy metals being released from coal will be present in our ecosystem forever, and will always be dangerous to human health (8).  A lot more coal is needed to be mined than uranium or thorium.  Not only does burning coal produce toxic gases, but around 300kg of fly ash, which contains uranium, thorium, and other radioactive chemicals, is produced per person in a developed country per year (4). 


Figure 5:  Comparing nuclear and coal power as sources for electricity.  *8,000 kWh average use per person per year for developed country (2)

Nuclear Power and Renewable Energy Sources
Getting energy from renewable energy sources such as those diagramed in Figure 6 has recently been attractive as they do not rely on fossil fuels.  The only drawback to renewable energy sources is that they are intermittent, and there is no large-scale means to store electricity for later use (2).  If Americans continue to expect electricity during the night or on days without wind, we must continue to rely heavily on base load power, which is mainly either coal or nuclear power.

Figure 6:  Diagram representing how a diverse number of renewable energy sources can provide all of US electricity by 2050 (9)


Conclusion

Therefore, although nuclear power does pollute the environment and cause some negative impacts to human health, in comparison to the other solution namely investing in coal it is less hazardous to the environment.  If the US invests in reprocessing fuel and using thorium rather than uranium, nuclear power’s impact on the environment can be farther reduced.  Renewable energy sources such as wind and solar power are much cleaner than nuclear power, but because there is no efficient means to store energy these energy sources cannot yet provide all the energy necessary to power America.  Investing in these energy sources is key to prevent future harm to the environment and prepare the US for switching over to these sources when the technology to store electricity is discovered.  However, because of global warming concerns and huge negative impacts that coal has on the environment and public health, coal should be phased out before nuclear power.  Even increasing nuclear power slightly to reduce the impact coal has on the environment would be a reasonable temporary solution.  However, primarily the US should invest in more renewable energy sources particularly in states that have large amounts of wind and are sunny nearly every day of the year.  Hopefully, phasing out coal and replacing it with renewable energy sources and cleaner nuclear power will provide a good stepping stone to a future where the US runs entirely on renewable energy. 

     
What to Do?

Create a website that would include the following:

  • The plan mentioned above
  • A comparison of all energy sources
  • Ways to conserve energy
  • Blog to express ideas
  • Letters to send to politicians
  • Allow selected companies to advertise to create money
  • Money Can be spent by
    •  Giving large grants to support research to find a way to store electricity and research in making nuclear power cleaner
    • Small grants to support community out reach in renewable energies

The website would attempt to attract the everyday person, who does not know very much about energy sources. 

Author: Rebecca Schwantes