Nuclear Power

How does it work? Uranium-235 is often use to fuel nuclear power plants. It has an interesting property that makes it useful for this because it can undergo induced fission.

Nuclear Fission

Chain Reaction When the neutrons ejected from each fission hit another nearby nucleus, that one splits and releases more neutrons, etc. This sets up a chain reaction that keeps going and going until……………..

Control Rods are put into action These are made of a material that absorbs neutrons and are lowered when the reaction needs to be slowed down or stopped.

How is the electricity created? The uranium bundle generates the heat which turns the water into steam. This drives the turbine, which spins a generator to produce power.

Outside the Power Plant Once you get past the reactor itself, there is little difference between a nuclear power plant and a coal or oil powered one.

The containment vessel Nuclear reactors are typically housed inside a concrete liner that acts as a radiation shield. That liner is housed inside a much larger steel containment vessel.

Advantages of Nuclear Power Minimal air pollution Water pollution is low (some thermal pollution exists) Disruption of land is low to moderate (except the mining of uranium) One pound of U-235 can produce as much heat energy as 1,500 tons of coal!

Disadvantages of Nuclear Power Highly toxic nuclear waste produced (some take thousands to millions of years to decay) Lifespan of facilities only 15-40 years Low net energy yield – lots of energy required for mining uranium, processing ore or dismantling the plant Safety and malfunction issues

So where does the plutonium come from anyway? Power plants create it when the uranium in their fuel fissions. Some of it ends up in the spent fuel as waste. Different isotopes of plutonium have different half-lives and different uses

What is a breeder reactor? The Breeder Reactor was developed to use uranium-238. Here's how it works. A reactor is built with a core of fissionable plutonium, Pu-239. The plutonium-239 core is surrounded by a layer of uranium-238. As the plutonium-239 undergoes spontaneous fission, it releases neutrons. These neutrons convert uranium-238 to plutonium-239. In other words, this reactor breeds fuel (Pu-239) as it operates. After all the uranium-238 has been changed to plutonium-239, the reactor is refueled. Plutonium production reactors operated by the U.S. government during the Cold War have all shut down.

Nuclear Power Plants in the United States

Who relies most on nuclear energy?

Nuclear Catastrophes

The INES scale The International and Radiological Event Scale is a worldwide tool for communicating to the public in a consistent way the safety significance of nuclear and radiological events.

Three Mile Island March 1979 Pennsylvania INES Level 5

What happened? A cooling malfunction caused a partial meltdown. Some radioactive water was released as well as radioactive gas. Many people were evacuated. The reactor did not explode as feared. No one was killed. A 25 year follow-up study in 2004 of 35,000 residents within a 5 mile radius of TMI showed no significant increase in deaths from cancer.

The China Syndrome This movie, released in March of 1979 depicted a very similar fictional incident to that which occurred on Three Mile Island about a week after it was released in theaters!!

Chernobyl April 1986 Ukraine INES Level 7

What happened? They were running a safety check. Regulations called for a minimum of 30 control rods. Only 6-8 were used. This led to a series of events that caused rapid overheating and deformed the core. The extra control rods could not be inserted and the core melted, causing an explosion. Fires lasted for nine days.

They made some BIG mistakes: The emergency cooling system was turned off Past-due safety check was being run by inexperienced night crew Automatic safety devices that shut down the reactor were shut off Power output was lowered too much The plant had no secondary containment shell

The effects It caused 30 immediate fatalities to workers and exposed approx. 500,000 people to dangerous levels of radiation. Air currents carried radioactive particles high into the atmosphere and allowed spreading.

The result? These serious accidents put a definite halt on most plans to build new power plants in the United States and caused some that were already built to be shut down indefinitely. One such plant here on Long Island is…………..

Shoreham Power Plant Officially decommissioned in 1989 Customers are still paying for the 6 billion dollar debt it has left.(3% surcharge on their electric bills for 30 years)

Fukushima Daiichi Disaster Japan: March 11, 2011 Original INES Level 5/Upgraded to Level 7 in April

A powerful tsunami generated by a magnitude 9 A powerful tsunami generated by a magnitude 9.0 quake at sea slams into the power plant Damage is done to four of six reactors Cooling systems fail Fires are set off Hydrogen gas causes explosions Engineers use seawater in effort to cool down cores

The Outcome? The world becomes skeptical again about the use of nuclear energy as old fears are revived . A handful of workers at the plant were accidentally killed while trying to control the overheating reactors. It is estimated that 1,000 people will die from cancers which result from radiation exposure.

Electricity Production The World The United States