Nuclear Processes

Learning Target Radioactivity Understanding the difference between a nuclear process and a chemical reaction Define radioactivity Differentiate between alpha, beta, gamma radiation https://www.youtube.com/watch?v=3JnxmI1ojYc Radioactive by Imagine Dragons 3 min LecturePLUS Timberlake

Radioactivity One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie (1876-1934). She discovered radioactivity, the spontaneous disintegration of some elements into smaller pieces.

Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleus The nucleus opens, and protons and neutrons rearrange The opening of the nucleus releases a tremendous amount of energy that holds the nucleus together – called binding nuclear energy “Normal” Chemical Reactions involve electrons, not protons and neutrons

When atoms give off radiation (energy) they will ultimately become stable – non-radioactive.

Radiation cannot be felt, seen, heard, tasted, or smelled.

Radioactive decay occurs when: Unstable nuclei rearrange their protons and neutrons Elements with atomic # above 83 are radioactive. 3 types of particles are emitted: alpha α, beta β, and gamma γ. http://www.chemicalelements.com/elements/he.html

Types of Radiation Alpha radiation -- helium nucleus (2 protons and 2 neutrons) Beta radiation –electron Gamma radiation – high energy x-ray

Penetrating Ability

What can stop alpha, beta, gamma radiation? https://www.youtube.com/watch?v=kaS11fW7nNc4 min. LecturePLUS Timberlake

Two types of nuclear processes Fission (radioactive decay refers to a natural fission process) and Fusion There are two nuclear processes that you need to be familiar with – Fission and Fusion.

Understand the difference between the two Learning Targets Understand the difference between the two nuclear processes fission and fusion LecturePLUS Timberlake

Nuclear Fission Fission is the splitting of atoms These are usually very large atoms, so they are inherently unstable Fission chain has three general steps: 1. Initiation. Reaction of a single atom starts the chain (e.g., 235U + neutron) 2. Propagation. 235U fission releases neutrons that initiate other fissions 3. Termination.

Fission Bomb Design Little Boy U-235 Fat Man Pu These 2 fission bombs were detonated over the cities of Hiroshima (8/6/1945) and Nagasaki (8/9/1945) during WW11. Aftermath was devastating.

This photograph shows the stone steps of the main entrance of Sumitomo Bank which is only 250 meters from the hypocenter. It is believed that a person sat down on the steps facing the direction of the hypocenter, possibly waiting for the bank to open. By a flash of the heat rays with temperatures well over a 1,000 degrees or possibly 2,000 degrees centigrade, that person was incinerated on the stone steps. Up to about 10 years after the explosion, the shadow remained clearly on the stones, but exposure to rain and wind has been gradually blurring it. So, when the bank was newly built, the stone steps were removed and are now preserved at the Hiroshima Peace Memorial Museum.

https://www.youtube.com/watch?v=3eX3V-cL6gI History channel Tsar Bomba 8min Hydrogen Fusion Bomb

A Fission Reactor https://www.youtube.com/watch?v=MGj_aJz7cTs Inside a nuclear fission reactor 4min

Excessive heat can not be contained Nuclear Fusion Fusion Excessive heat can not be contained Attempts at “cold” fusion have FAILED. “Hot” fusion is difficult to contain https://www.youtube.com/watch?v=3eX3V-cL6gI Taylor Wilson – Star in a Jar nuclear fusion for energy 3.35 min

You will be able to identify common everyday Learning Target You will be able to identify common everyday uses that involve nuclear processes; radiation, radioactive decay, nuclear fission LecturePLUS Timberlake

Every Day Uses of Radioactive Materials and Radiation Radiation is used every day in our daily lives. Following are some examples.

Non-destructive testing Radiation is used to detect tiny cracks that might exist in plane engine turbine blades much like an x-ray is used to detect broken bones in a person. This is called radiography.

Carbon Dating – uses Carbon-14 to estimate age of organic (once living) material Carbon 14 dating of an artifact. Carbon 14 is a naturally radioactive isotope of carbon. Any thing that was or is living has Carbon 14 in it. By measuring the amount of Carbon 14 that is still left in the artifact that was made out of something that was once alive, its age can be accurately estimated.

Locating a pipeline leak A radioactive tracer was placed in a pipeline to allow workers with Geiger counters to find a leak.

Space batteries otherwise known as RTGs (radioisotope thermoelectric generator) Ulysses Satellite – studied the Sun The next Mars Rover – about the size of an SUV An astronaut working with a battery. Apollo missions to the Moon

Medical Uses Picture things Measure things Destroy things Power things Picture things: x-rays, MRI – magnetic resonance imagining (used to be call NMRI – nuclear magnetic resonance imaging), bone scans – a radioactive tracer is injected into a patient’s blood, allowed to travel for a few hours and then an image of the area of concern is taken. Measure things: thickness of a bone or tissue, bone density Destroy things: radiation is used to destroy cancer cells! (It can cause some kinds of cancer and is also used to kill it!) Power things: pace makers are powered with a plutonium battery that lasts about 5 years

Picture things like in an x-ray Measure things like in bone scans or brain scans Power things like a pacemaker Destroy things like in radiation treatment of cancer Medical uses of radiation – picture things like an x-ray machine, measure things like in a bone scan when blood activity is measured to see if bone cancer is present or measure brain activity for various studies, destroy things like in the radiation treatment of cancer, power things like a pacemaker which is powered by a radioisotope battery

Radioisotopes in Medicine 1 out of every 3 hospital patients will undergo a nuclear medicine procedure 24Na, t½ = 14.8 hr, b emitter, blood-flow tracer 131I, t½ = 14.8 hr, b emitter, thyroid gland activity 123I, t½ = 13.3 hr, g-ray emitter, brain imaging 18F, t½ = 1.8 hr, b+ emitter, positron emission tomography 99mTc, t½ = 6 hr, g-ray emitter, imaging agent Brain images with 123I-labeled compound 23.7

Irradiation of Food the process of exposing food to high levels of radiation to destroy microorganisms, bacteria, and insects that might be present in the food

Kills bacteria which slows the ripening and sprouting of fruits and vegetables. These onions and potatoes are all the same age. The only difference is the ones on the left have been irradiated (exposed to high levels of radiation) to kill the bacteria that cause food borne illness, ripening and sprouting.

Chemistry In Action: Food Irradiation Dosage Effect Up to 100 kilorad Inhibits sprouting of potatoes, onions, garlics. Inactivates trichinae in pork. Kills or prevents insects from reproducing in grains, fruits, and vegetables. 100 – 1000 kilorads Delays spoilage of meat poultry and fish. Reduces salmonella. Extends shelf life of some fruit. 1000 to 10,000 kilorads Sterilizes meat, poultry and fish. Kills insects and microorganisms in spices and seasoning.

Food IS NOT radioactive after it has been irradiated Food IS NOT radioactive after it has been irradiated. Irradiation just kills the living things inside the food. A food irradiation facility. The potatoes, in this case, are brought in on a conveyor belt. The room is closed off with shielding and the radioactive source is lifted out of its housing below water for the proper period of time. The source is then returned to its housing under water and the food goes on its way while more is brought in for irradiation.

No dairy products – irradiation activates the enzyme that makes it smell sour. A list of food items that are currently irradiated. Notice dairy products are not listed. Irradiating dairy products causes the enzyme that makes them smell sour to activate. So, while the dairy product is still fine to consume, it would smell pretty bad. Spices found in your kitchen right now have very likely been irradiated.

Did you know bananas are radioactive? Check the peel next time you eat one! The warning signs you see on the inside of banana peel because it contains a radioactive substance. (Not really!) All bananas have a naturally occurring radioactive isotope of potassium (Potassium 40) in them. This does not make them unsafe to eat!

Irradiating food could DRAMATICALLY reduce food poisoning and massive food recalls. Information about salmonella bacteria which is found in chicken. Numbers of poisonings and deaths are probably low because symptoms are very similar to the flu.

No bacteria = no eye infection or worse! Make-up is irradiated. No bacteria = no eye infection or worse! A list of countries who irradiate food. While the U.S. is on the list, its irradiation of food is highly limited due to lack of education and acceptance of the general public. Irradiating food could prevent and nearly eliminate food borne illnesses caused by e-coli, trichinosis, and salmonella not to mention increase the shelf life of the foods.

Beyond irradiating food to make is safer and last longer, irradiation is commonly used (even in the U.S.) to sterilize various products and supplies. You would not want to put mascara near your eye that had not been irradiated to kill the bacteria in it. You would likely wind up with an eye-swollen shut rather than looking attractive.

Nuclear Powered Aircraft Carriers and Submarines An aircraft carrier that is powered by two nuclear reactors. The carrier can outrun all its accompanying ships that are powered using gasoline or diesel engines. Its top speed is upwards of 35 knots (over 40 miles per hour) – the actual speed is classified. Pretty fast for a ship that weighs over 97,000 tons!

Radiation and You

Some sources of radiation you might have around you on a given day.

Background radiation due to various activities or based on where you live.

Background radiation based on where you work Background radiation based on where you work. Note: The value given for an x-ray technician is higher than current exposure rates. This has been greatly reduced with advances in shielding and focusing the x-ray beams.

Natural background radiation based on the state you live in Natural background radiation based on the state you live in. These vary due to elevation differences and land formation differences.

Radiation Protection Factors Time Distance Shielding Quantity A reduction in the amount of time a person is exposed to radiation reduces their dose. Radiation decreases according to the inverse square law as it relates to distance. What this means is, if you double your distance from a radiation source, your dose will be one quarter as much. If you triple your distance, your dose will be one ninth as much. If you quadruple your distance, your dose will be one sixteenth as much and so on. The use of shielding or something between you and the radioactive source protects you from exposure. The amount of radiation or radioactive substance involved in your exposure also has an effect. The smaller the source, the lower your dose.

All substances are poisons. There are none which is not a poison All substances are poisons. There are none which is not a poison. The right dose differentiates a poison and a remedy. Paracelsus 1493-1541 A quote from an ancient wise man. The amount of any substance is what determines if it will be a poison or a remedy. Otherwise summed up with the following statement: “the dose makes the poison”.