Nuclear Energy Notes 18.2 & 18.3

1.Nuclear Reactions : Change the composition of an atom’s nucleus. 2. The strong nuclear force holds the nucleus together. 3. Most atoms are stable (equal number of p & n ). These are the smaller atoms which are NOT radioactive.

4. Unstable nuclei have more neutrons than protons. These isotopes are radioactive. 5. As the elements become larger they become more unstable. 6. All elements have at least 1 radioactive isotope. All the isotopes of those elements with atomic numbers greater than 83 are radioactive.

Unstable Nucleus

8. Characteristics of Subatomic Particles and Rays: Particle Mass (amu) ChargeSymbolStopped by Proton Neutron Beta Particle (electron) Alpha Particle (He nucleus) Gamma Ray Several centimeters of lead paper Heavy clothing/Al foil Few centimeters of lead paper p + or n 0 or

Nuclear Radiation Penetrating Power

9. Spontaneous Emission of Radiation: A. Unstable nuclei will spontaneously emit 3 types of natural radiation, this is also called radioactive decay. B. When an atom emits 1 kind of radiation the original nucleus decomposes or decays to form a new nucleus and releases radiation. This is written in a nuclear equation.

Alpha & Beta Decay

10. 3 Types of Spontaneous Radiation : A. Alpha Decay – spontaneous emission of an alpha particle from the nucleus. B. Beta Decay – spontaneous emission of beta particle from the nucleus C. Gamma Decay – spontaneous emission of gamma rays from the nucleus

Uranium Radioactive Decay Series

How Radon Gas Enters your House

Ways to Remove Radon Gas from Your Home

External view of a Radon mitigation system from a home basement. Below is a view of the fan inside which runs 24 hours a day pulling air from under the basement floor.

Testing Methods for Radon

U.S. Radon Zones

11. Transmutation: Changing into a new element by either decay or bombardment. Nuclear Bombardment Reactions A. Process in which a new element is formed by bombarding a nucleus with small energetic particles. B. The energetic particle hits the nucleus and forms an unstable compound nucleus, which is short- lived. C. This nucleus can emit another particle to stabilize itself. D. This is the process used in particle accelerators where artificial isotopes and transuranium elements have been produced.

Particle Accelerator in Switzerland with a 16.7 mile circumference

Nuclear Bombardment Reaction target nucleus projectile new isotope (element) ejected particle

12. Nuclear Fission A.Process by which a heavy nucleus splits into two smaller nuclei. B.Most fission reactions are induced. C.The energy yield for fission reactions are very high. D.Fission reactions are the source of energy used to generate electricity in nuclear power plants. E. U-235 & Pu-239 are the radioisotopes used in reactors.

Fission Is Similar To Pool

Nuclear Fission Reaction Nuclear fuel projectile – particle that starts the chain reaction temporary unstable nuclei that immediately splits into 2 approximately equal mass product nuclei 3 neutrons are produced which start additional fission reactions

F. In fission reactions, the product nuclei have far too many neutrons, and are intensely radioactive. This is considered radioactive waste. G. The released neutrons can cause another reaction as long as sufficient U-235 remains. H. This is called a chain reaction. I. The smallest amount (minimum volume) of fissionable material needed to sustain a chain reaction is called the critical mass.

Nuclear Chain Reaction Fuel: U-235 or Pu-239 Critical mass for U is 110 lbs

16. Nuclear Fusion: A. This is a thermonuclear reaction - requires high temperatures. B. Occurs when two small nuclei fuse, or join, to form larger, more stable nuclei. C. Releases a large amount of energy. D. Process that occurs on the sun and in a hydrogen bomb. E. If fusion reactions are going to be practical, they need to produce more energy than they require to get started. F. In a fusion reaction, the starting materials are in a form of plasma. G. The biggest problem is obtaining the high temperatures necessary for a fusion reaction to occur. H. A “ magnetic bottle ” is used to hold plasma at high temperatures.

neutron U-235 Energy Krypton-92 3 neutrons Barium-141 Fission Fusion Nuclear Power Plants/A-bomb The Sun/ H-bomb

A wooden house built 1km away from the test site… The first Atomic Bomb is detonated at Trinity Site near Alamogordo, New Mexico on July 16, A Monument stands at the test site today. shows the result of the blast.

“Little Boy” Uranium fission bomb dropped on Hiroshima, Japan by the “Enola Gay” flown by Colonel Paul Tibbets

Hiroshima - August 6, 1945 Distance from Ground Zero (km) KilledInjuredPopulation %10% 31, %37%144, %25% 80,300 Total27%30%256,300

Hiroshima 1945 & Today

Nagasaki - August 9, 1945 Distance from Ground Zero (km) KilledInjuredPopulation % 6% 30, %29%144, %10% 15,200 Total22%12%173,800 “Fat Man” – Plutonium Fuel

U.S. Nuclear Testing Large craters pockmark Frenchman Flats, Nevada, a former test site for U.S. nuclear weapons. The US conducted more than 1050 tests here and in Alaska, Colorado, Mississippi, New Mexico between 1945 and The Soviet Union, UK, France, China, India and Pakistan had a similar total number of tests over the same time period.

Fusion Bombs The first thermonuclear weapon (hydrogen bomb), code-named Mike, was detonated at Enewetak atoll in the Marshall Islands, Nov. 1, The photograph was taken at an altitude of 12,000 feet over 50 miles from the detonation site.

Only 6 countries have detonated a hydrogen bomb – US, UK, Soviet Union, France, China and India. To obtain temperatures in the millions of degrees Celsius a fission reaction is set off first to start the fusion reaction.

Nuclear Reactors A.There are currently 111 commercial nuclear power plants in the U.S. They provide 20% of our country’s electricity, but 80% of the electricity used in southeastern PA.

B. There are 530 nuclear reactors in 30 nations around the world that provide 1/6 of the world’s electricity. To produce electricity you need to turn a turbine. This can be accomplished by wind or water, must most commonly by steam. The only difference between a nuclear power plant and a conventional fossil fuel plant is the method used to produce boiling water.

14. Parts of a Nuclear Reactor A.Fuel Rods: Composed of 97% U-238 and 3% U-235 (the fissionable isotope). Chalk - sized pellets are arranged in long steel cylinders in the reactor core. When the fuel has given up most of its energy it is called spent. It will be reloaded every 1 to 3 years. There can be 10,000,000 pellets in 1 plant. B. Control Rods control the rate of a nuclear reaction. Without them the reaction would occur too fast for it to be effective. C. Moderator is usually heavy water (D 2 O). Without sufficient cooling of the core a meltdown could occur. This water also shields workers.

Nuclear Power Plant Control Room

View of fuel rods and control rods immersed in “heavy water.”

Fuel Rods Filled With Pellets Are Grouped Into Fuel Assemblies

D. Generator produces electricity by turning a steam turbine from the boiling water. E. Cooling System: Water from outside is used to cool the steam (it does not come into contact with the cooling water in the core). Excess steam rises up in the cooling tower, condenses and falls back. 14. Parts of a Nuclear Reactor con’t. Cooling Towers Limerick, PA

Nuclear Power Plant Turbine and Generator Spinning turbine blades and generator Boiling water Steam

Nuclear Power Plant Diagram

Pressurized-Water Reactor

Boiling Water Reactor Boiling-Water Reactor

France42.6 Sweden36.2 Lithuania31.9 Armenia27.7 Slovakia24.8 Bulgaria24.3 Switzerland22.5 Belgium21.9 Slovenia21 Korea (Republic of)17.9 Finland17.3 Ukraine16.1 Japan15 Czech Republic14.3 Hungary13 Germany12.3 Spain10.3 United Kingdom9.1 United States9 Canada8.8 Russian Federation6.1 Romania3.8 Argentina2.8 South Africa2.3 Mexico1.6 Netherlands1.3 Brazil1.2 China0.8 India0.8 Pakistan0.8 Nuclear power (% of total primary energy supply) IEA (International Energy Agency) 2007

56% COAL 9.6% GAS 3.7% OIL 9.5% HYDRO 21% NUCLEAR 0.2% GEOTHERMAL & OTHERS Electricity Generation Sources in U.S.

Wind And Solar Are Great, But… Nuclear Coal Natural Gas Wind Hydro 89.6% 70.6% 39.9% 33.0% 30.2% Availability

One fuel pellet = One fuel pellet produces as much energy as: 3 barrels of oil 1 ton of coal 2.5 tons of wood 17,000 cubic feet of natural gas

15. Radioactive Waste: A. Spent fuel rods have been accumulating for about 40 years. Spent fuel rods are highly radioactive, with some isotopes remaining active for thousands of years. By federal law reactor waste must be stored on site. The U.S. Government has not yet opened any permanent storage sites, but one called Yucca Mountain in Nevada is currently being negotiated. On-site storage is only a temporary measure, as tanks require too much maintenance to be safe for long term storage.

Radioactive Waste Radioactive waste is stored under water until it decays to lower levels. Radioactive Warning Symbol

Waste is transferred to storage casks and stored on-site at each power plant. Temporary Radioactive Waste Storage

If permanent storage is opened, it would be transported to a location where it would be placed ½ mile underground in mine shafts drilled in rock that is above the water table and free from seismic activity. Permanent Radioactive Waste Storage

Current Waste Storage Locations

Nuclear Accidents Three Mile Island March 28, 1979 on the Susquehanna River near Harrisburg, PA. The worst nuclear accident in U.S. history was caused by technical failures and human error. About 2 million people were exposed to 1mrem of radiation which led to no deaths or injuries.

Chernobyl April 26, 1986 in the northern Ukraine. The core melt meltdown caused radioactive materials to spread over a wide area of Europe. Officials at a Sweden Nuclear Power Plant 1 st noticed that radioactive particles were on their clothes and thought their own plant was malfunctioning. The worst nuclear accident in the world was caused by a flawed reactor design and inadequately trained operators. Nuclear Accidents

57 immediate deaths with 4000 additional cancer deaths long term. Over 360,000 people were evacuated permanently from the area which remains closed. The initial cover-up of the incident made clean up worse.

Fukushima March 11, 2011

17. Uses for Nuclear Chemistry: A. Half life 1. The time required for ½ of the atoms of a radioactive isotope to decay. 2. Using radioactive isotopes to determine the age of an object is called radio carbon dating. Ex. If I have 1.00 mg of, which has a ½ life of 8.04 days, how much will be left after 1 half-life? After 2? After 3?

B. Radioactive Isotopes and Dating 1. All animals and plants contain carbon Even though carbon-14 undergoes radioactive decay, it is constantly replenished during a lifespan. 3. The half-life of carbon-14 is 5730 years. 4. The ratio of C-12 to C-14 is compared to another object of a similar age. 5. Cannot use carbon-14 dating with objects that never lived.

6. After 4 half lives, the amount of carbon-14 remaining is too small to give reliable data. 7. Carbon-14 is not useful for specimens over 25,000 years old, so Potassium-40 is used instead. It has a half-life of 1.28 billion years.

Radioactive Decay of Strontium-90 What is the ½ Life of Strontium-90??? 28 years How long until no more Strontium-90 remains?

What is the ½ Life of this Radioactive Sample? 2 days

C. Smoke Detectors: 1. Smoke detectors emit a small amount of alpha particles. 2. When smoke particles mix with the gas, they slow the current flow setting off the alarm.

D. Medical Uses 1. CAT SCAN – the body is analyzed using X-rays.

2. MRI and NMR – detects body’s absorption of radio waves.

3. PET – Measures gamma rays from certain part of the brain.

4. Radioisotopes prepared in a nuclear reactor can be used to both treat and detect various medical conditions. Tracers can be used to follow a particular isotope through its normal path in the body to show any abnormalities. Ex) Upper and Lower GI uses radioactive Barium to detect stomach and intestinal problems. An IVP measures the bodies absorption of radioactive iodine to detect kidney stones.

5. Irradiation can be used as an energy source to treat cancer. The diseased area is exposed to ionizing radiation to kill cancerous cells. Ex) Ingest large amounts of I-131 kills thyroid cancer, External beam of Co-60 can be directed at a cancerous spot. Irradiation can also be used to sterilize medical instruments and preserve food. Food Irradiation Symbol

Radioisotopes found in various parts of the body

18. Exposure to Radioactivity: A. Continued exposure to radiation is dangerous; therefore, people working in these conditions must monitor their exposure to radiation. B. People working with radiation wear film badges to monitor their exposure.

C. A dosimeter measures radiation in people, a Geiger Counter measures radiation of objects. D. Radiation is usually measured in units of mrems. Higher doses for a longer period of time over a large area cause the most damage, especially for rapidly dividing cells like sex cells and blood cells.

Sources of Our Radiation Exposure

81 Radiation Exposure From Different Activities (in millirem) Natural Background Radiation (1 year) Working at a Nuclear Power Plant (1 year) One Diagnostic X-ray Living in a Stone, Brick or Concrete Building (1 year) One Cross-Country Flight Watching TV (average person, 1 year) Living Within 50 miles of a Coal-Fired Plant (1 year) Living Within 50 miles of a Nuclear Plant (1 year)