Nuclear Energy More Bang for your Buck?

Is it Green?

Or YELLOW?!?

Introduction XQ XQ

Basic Terminology Isotopes= atoms with an exceptional number of neutrons. Fissile= a term used to describe an isotope that can be split into separate pieces. 238 U= the naturally occurring form of Uranium, along with 235 U (the fissile form). Atom= has both neutrons, protons, and electrons; the fundamental structure of elements.

How it Works Fissile Uranium-235 consists of 92 protons and 143 neutrons, a combination that is slightly unstable. If it is struck by a neutron, it will split into two unequal parts, called fission products, throwing off three neutrons, on average, and some energy. These three new radical neutrons can split three new 235 U atoms, and so on (causing a chain reaction). This reaction is controlled inside a nuclear power plant, it isn’t inside a nuclear bomb.

The Immediate Products Nuclear fuel only consists of 3% to 5% 235 U, the rest being the more stable 238 U. Most neutrons don’t hit 235 U, but instead impact 238 U, creating the slightly unstable 239 U. Uranium-239 throws off beta particles (essentially turning neutrons into protons), and eventually becomes plutonium P is a fissile element that can be split to produce additional energy, which actually begins happening after a number of years.

ALPHA AND BETA DECAY Alpha decay: The emission of an alpha particle (two protons and two neutrons) from a large, radioactive nucleus Ex: 238 U → 234 Th + 4 He 2+ Beta decay: The decay of a neutron into an electron, a proton, and an antineutron Ex: n 0 → p + + e - + v e

So Why Does Nuclear Fuel Run Out? The fissile products of the original 235 U reaction begin to accumulate, and after a period of about 5 years, they begin to poison the reaction by blocking the neutrons. The reaction fizzles out, and the fuel must be recycled. The fissile products include strontium-90 and cesium-137, which emit beta and gamma radiation. The required storage time for these products is ~200 years.

What Makes Waste Bad? The fissile products include strontium-90 and cesium-137, which emit beta and gamma radiation. The required storage time for these products is ~200 years. Alpha radiation= stopped by skin/clothing. Beta radiation= stopped by thick glass/firefighter gear. Gamma radiation & neutrons= stopped by 3ft of concrete.

Uranium Enrichment Naturally occurring uranium stores are 99.29% 238 U, and only 0.71% 235 U. In order to obtain the necessary 3% to 5% 235 U mixture, the uranium must be enriched. Enrichment is performed by dissolving the original uranium ore, mixing it with fluorine to form a gas, and centrifuging it. The heavier, 238 U goes to the bottom of the centrifuges, where it is siphoned off. Nuclear bombs are so expensive b/c the require 93% 235 U!

A Common Misconception Nuclear fuel CANNOT be made into a nuclear weapon without starting completely over, essentially from ground zero. SO, unless a country has the necessary enrichment facilities for a nuclear bomb in the first place, they can have as many power plants as they like, and still can’t have nuclear weapons!

Can We Get Some Einstein up in Here?? E=mc 2  the energy produced is equal to the mass lost times the speed of light squared. Accordingly, 1 ounce of U converted to energy has the energy equivalent of over 75 tons of coal. Why? Because there is a mass difference between 235 U and the fissile products!

How Does it Stack up? Nuclear energy worldwide has saved over 100 billion tons of CO2 from entering the atmosphere since Energy use in US in about 70% fossil fuel, 20% nuclear, 10% everything else. A 1000 MW coal plant – Uses 3,500,000 tons of coal/year – Produces 8,000,000 tons of CO2/year – Produces 440,000 tons of haz waste/year A 1000 MW nuclear plant – Uses 29 tons of fuel (4% enriched)/year – Produces <1000 tons of CO2/year – Produces 10 tons of haz waste, and 5 tons of nuclear waste.

ETHICAL/PRACTICAL ISSUES $$$ Cost $$$ Risk/Danger Waste Disposal Uranium Mining Public Misconception

Nuclear Power by State Number of states with operating reactors : 31 In six states in 2007, nuclear power made up the largest percentage of their electricity generated: State Percent : Vermont 73.7 South Carolina 51.2 New Jersey 50.7 Connecticut 48.9 Illinois 47.8 New Hampshire 46.0

CHERNOBYL The most devastating nuclear power plant disaster in history Occurred April 26, 1986 at 1:23 a.m. Located in Ukraine, which was then a part of the Soviet Union Catastrophic power excursion, steam explosion, torn reactor, released cesium-137 and strontium directly attributed death, but may be as many as 600,000 exposed to negative health effects from radiation

Storage Harmful waste is often stored underground and underwater. Most waste is only in temporary storage (i.e. concrete blocks, steel drums, etc.) Ambitious projects are being undertaken in NM, Waste Isolation Pilot Plant. Most waste is in form of contaminated materials (i.e. clothes, construction, etc.)