Uranium, radioactivity and the environment?

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art7319's profile pic

art7319 | High School Teacher | (Level 1) Adjunct Educator

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Uranium, #92, comes in two basic forms, U235, and U238.

U238 is not radioactive and is the heavier of the two isotopes.  U235 on the other hand is radioactive, which means that it gives off particles of radiation as it decays.

U235 is an unstable element.  It does not have enough neutrons when compared to the number of protons in the nucleus and therefore starts to break apart into smaller fragments.

There are three basic types of radiation.  The alpha particle which is basically a helium ion, the high speed electron and the gamma ray.

All of these radiation particles are not good for the environment in high concentrations and they are not found that way in nature.   Man has devised a way to increase the concentration of U235 from it small amount at any one location to a critical mass in some cases to allow the reaction of decay to be harnessed to make electricity.

The down side of all this is that the by products of this reaction and all radioactive reactions are that the end products are usually more radioactive for longer periods of time and in larger concentration than when originally found in nature.

Thus we have to store these by products for thousands to hundred of thousands of years before they are safe to the environment and man.

So the ends does not justify the means as we have no safe perminant location to store the waste products yet.  So why make more?

giorgiana1976's profile pic

giorgiana1976 | College Teacher | (Level 3) Valedictorian

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One of the main problems, of whose solution depends on the development of our civilization, is providing the energy needed to the development of activities of the progressive evolution of living standards of population of the earth.The amount of energy consumed by mankind has grown from primitive times until now, 2.5 million times.It is clear that such growth can lead to a problem of energy needed for future development of mankind .
Obtaining nuclear energy is conditioned by the presence of radioactive radiations.Fission is the basis to obtain nuclear energy.
The A state of the core is spherical due to link energy analogous to surface tension of the droplet.When the nucleus absorbs a neutron to form an excited nucleus B, its energy is about equal to the energy core plus a neutron kinetic energy and can occur

  - ifexcess energy is insufficient to show the distortion, from the state C the core becomes spherical and stable and the excess energy is delivered as radiation "(in 16% of cases);

-if the excess energy exceeds a certain value, called "critical energy" occurs breakage kernel in two parts (state D fission), which can deliver a number of neutrons (state E).

Nuclear fission products (fragments) in state D have very rare kernels with equal masses, the yield in this case is less than 0.1% (symmetric fission).In most cases, nuclear fission is "Unsymmetrical" resulting  different mass kernels.In an act of nuclear fission was calculated how much energy is released for uranium-235:

- Fission products: 166 MeV (82.5%) - Radiation fission: 6 MeV (2.95%)
- Radiation: 7 MeV (3.4%)
- Neutrinos: 11 MeV (5.4%)
- Radiation delayed: 6 MeV (2.95%)
- Neutrons: 5 MeV (2.8%)
Uranium exists in Earth's crust, down to depth of 16 km, with an average abundance of 10.5% ,overccoming abundance of metals such as mercury, silver, bismuth and cadmium. In water seas and oceans is found uranium in the form of soluble salts, with concentrations ranging between 10.7 and 0.4 * 23 * 10-7g/l. There are distinguished three categories of rocks that may contain uranium. The first two contain primary respectively secondary uranium minerals , the third category contains uranium as an impurity included in the crystalline network. Rainfalls which wash contaminated landfills are a source of contaminating surface water and groundwater with radioisotopes or other toxic substances (arsenic and heavy metals). Thus, waste dumps located near residential areas pose a risk to people.

 

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