Скачать презентацию Nuclear Energy Chapter 15 15 1 RADIOACTIVITY Скачать презентацию Nuclear Energy Chapter 15 15 1 RADIOACTIVITY

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Nuclear Energy Chapter 15 Nuclear Energy Chapter 15

15. 1 RADIOACTIVITY 15. 1 RADIOACTIVITY

Remember: Atoms are made of protons, neutrons, and electrons Remember: Atoms are made of protons, neutrons, and electrons

Most atoms are stable They have a correct balance of protons and neutrons. Most atoms are stable They have a correct balance of protons and neutrons.

Other atoms are unstable They have an “off-balance” number of protons and neutrons. Other atoms are unstable They have an “off-balance” number of protons and neutrons.

Atoms whose nuclei are unstable are said to be radioactive Atoms whose nuclei are unstable are said to be radioactive

Eventually, these atoms breakdown. Eventually, these atoms breakdown.

The process is called “radioactivity”. The process is called “radioactivity”.

Radioactivity is not new. Radioactivity is not caused by man. Radioactivity is not new. Radioactivity is not caused by man.

Radioactive decay in Earth’s interior heats the water for geysers Radioactive decay in Earth’s interior heats the water for geysers

Radioactive decay in Earth’s interior heats the water for hot springs Radioactive decay in Earth’s interior heats the water for hot springs

Most of the radiation we encounter Most of the radiation we encounter

Nuclear Technology - Pros • Medical X-rays & Anti Cancer Treatments Nuclear Technology - Pros • Medical X-rays & Anti Cancer Treatments

Nuclear Technology - Pros • Smoke detectors Nuclear Technology - Pros • Smoke detectors

Nuclear Technology - Pros • Nuclear Energy Nuclear Technology - Pros • Nuclear Energy

Nuclear Technology - Cons • Nuclear Disaster Nuclear Technology - Cons • Nuclear Disaster

Nuclear Technology - Cons • Nuclear Weapons Nuclear Technology - Cons • Nuclear Weapons

Nuclear Technology - Cons • Nuclear Weapons Nuclear Technology - Cons • Nuclear Weapons

Nuclear Technology Demands Responsibility • Safeguard nuclear material • Safe, clean disposal • Protect Nuclear Technology Demands Responsibility • Safeguard nuclear material • Safe, clean disposal • Protect the environment for future generations

It’s up to you to make the decisions for the future! It’s up to you to make the decisions for the future!

Chapter 15. 2 Alpha, Beta, and Gamma Rays Chapter 15. 2 Alpha, Beta, and Gamma Rays

Radioactive elements emit 3 different types of particles α alpha β beta γ gamma Radioactive elements emit 3 different types of particles α alpha β beta γ gamma

α particles are positively charged β particles are negatively charged γ particles are neutral α particles are positively charged β particles are negatively charged γ particles are neutral

• http: //www. youtube. co m/watch? v=o 9 yt 7 OAYm. E • http: //www. youtube. co m/watch? v=o 9 yt 7 OAYm. E

α particles are He nuclei α particles are He nuclei

α particles are Helium nuclei α particles are Helium nuclei

α particles • Relatively low speed • Eventually become HE • Easy to shield α particles • Relatively low speed • Eventually become HE • Easy to shield against • Can’t go through paper or clothing

β particles are electrons • Neutrons “decay” • Produce a proton and electron β particles are electrons • Neutrons “decay” • Produce a proton and electron

β particles • • Faster than α particles Can penetrate paper and clothes Can β particles • • Faster than α particles Can penetrate paper and clothes Can penetrate and damage skin Can not penetrate denser material like aluminum

γ (gamma) rays are pure energy • Gamma rays have more energy than visible γ (gamma) rays are pure energy • Gamma rays have more energy than visible light, UV light or X-rays

γ (gamma) rays • Can easily penetrate and damage living tissue • Can penetrate γ (gamma) rays • Can easily penetrate and damage living tissue • Can penetrate most materials – except lead

Let’s Compare Penetrating Power Let’s Compare Penetrating Power

γ (gamma) rays can help preserve food γ (gamma) rays can help preserve food

Question • Pretend you are given three radioactive rocks. • One is an alpha Question • Pretend you are given three radioactive rocks. • One is an alpha emitter, one is a beta emitter and one is a gamma emitter and you know which is which.

Question • You can throw one away. • Of the other two, you must Question • You can throw one away. • Of the other two, you must hold one in your hand place one in your shirt pocket.

Question • What can you do to minimize your exposure? Question • What can you do to minimize your exposure?

Answer • Hold the alpha emitter in your hand. • The skin on your Answer • Hold the alpha emitter in your hand. • The skin on your hand will shield you.

Answer • Put the beta emitter in your pocket. • The combined thickness of Answer • Put the beta emitter in your pocket. • The combined thickness of you skin and clothing should shield you from the beta emissions.

Answer • THROW AWAY THE GAMMA EMITTER! • Because it would penetrate your body Answer • THROW AWAY THE GAMMA EMITTER! • Because it would penetrate your body from any of these locations.

Answer • In a perfect world…… • Distance yourself from all the rocks!. Answer • In a perfect world…… • Distance yourself from all the rocks!.

Chapter 15. 3 Environmental Radiation Chapter 15. 3 Environmental Radiation

Most radiation we encounter originates in nature • Common rocks and minerals Most radiation we encounter originates in nature • Common rocks and minerals

Which family is exposed to more radiation? The one living in a Brick house? Which family is exposed to more radiation? The one living in a Brick house? Or the one living in a wooden house?

• More radiation exposure • Naturally Occurring • More radiation exposure • Naturally Occurring

• Radon A Common Source of Radiation • Radon A Common Source of Radiation

• Heavy, inert gas • Arises from uranium deposits • Heavy, inert gas • Arises from uranium deposits

Is Radon Dangerous? • According to the EPA, radon is the second leading cause Is Radon Dangerous? • According to the EPA, radon is the second leading cause of lung cancer. • It is the leading cause of lung cancer in non-smokers.

How radon produces cancer How radon produces cancer

Levels vary with geology Levels vary with geology

You can check radon levels with a test kit You can check radon levels with a test kit

High levels require action High levels require action

Here’s another interesting question…. Here’s another interesting question….

Which is a greater source of radiation? Coal Combustion Nuclear power Which is a greater source of radiation? Coal Combustion Nuclear power

The Coal Industry! • Global combustion of coal releases about 13, 000 tons of The Coal Industry! • Global combustion of coal releases about 13, 000 tons of radioactive thorium and uranium into the atmosphere. • In addition to other polluting molecules released into the air.

• Worldwide they generate about 10, 000 tons of radioactive waste each year • Worldwide they generate about 10, 000 tons of radioactive waste each year Nuclear plants • Almost all the waste is contained and not released into the atmosphere.

RADIATION DAMAGE TO THE BODY RADIATION DAMAGE TO THE BODY

Remember • Most of the radiation we receive is from natural sources and medical Remember • Most of the radiation we receive is from natural sources and medical procedures

The human body itself is a source of radiation! The human body itself is a source of radiation!

K The radiation comes from the potassium we eat. K The radiation comes from the potassium we eat.

Our bodies contain about 200 mg K ≈ 20 mg K 40 *radioactive* β Our bodies contain about 200 mg K ≈ 20 mg K 40 *radioactive* β emitter ≈ 180 mg other K isotopes

Between every heartbeat… ≈ 5000 K 40 undergo spontaneous radioactive decay! Between every heartbeat… ≈ 5000 K 40 undergo spontaneous radioactive decay!

Radiation is everywhere! Radiation is everywhere!

Radiation cause damage to cells Radiation cause damage to cells

Radiation cause serious burns and hair loss Radiation cause serious burns and hair loss

Cells can repair radiation damage if it is not too severe Cells can repair radiation damage if it is not too severe

Radiation can damage DNA Radiation can damage DNA

Radiation can damage DNA resulting in cancer Radiation can damage DNA resulting in cancer

High doses of radiation can damage DNA resulting hereditary birth defects High doses of radiation can damage DNA resulting hereditary birth defects

• Avoid radiation when possible • All radiation can not be avoided • • Avoid radiation when possible • All radiation can not be avoided • Most is simply part of nature Common sense

Chapter 15. 5 HALF- LIFE Chapter 15. 5 HALF- LIFE

Radioactive isotopes decay at different rates • Measured in terms of a characteristic time Radioactive isotopes decay at different rates • Measured in terms of a characteristic time • “Half-life”

Half-life The time needed for half the radioactive atoms of a radioactive material to Half-life The time needed for half the radioactive atoms of a radioactive material to decay

Radium (Ra 226) • Half life = 1620 years Radium (Ra 226) • Half life = 1620 years

Half lives are constant • Not affected by external conditions • Some are less Half lives are constant • Not affected by external conditions • Some are less than 1/1, 000 sec • Some are much longer

Uranium - 238 • Half life = 4. 5 billion years • In 4. Uranium - 238 • Half life = 4. 5 billion years • In 4. 5 billion years, half the uranium on earth will be lead!

ISOTOPIC DATING ISOTOPIC DATING

• Cosmic rays constantly bombard the atmosphere • Radioactive C 14 is ultimately • Cosmic rays constantly bombard the atmosphere • Radioactive C 14 is ultimately produced.

14 C 14 CO O 2 Carbon dioxide takes C 14 into the food 14 C 14 CO O 2 Carbon dioxide takes C 14 into the food cycle 2

Animals eat the plants so all animals have some C 14 in them Animals eat the plants so all animals have some C 14 in them

…. . so all living things on Earth contain some C 14 …. . so all living things on Earth contain some C 14

After death C 12 remains constant The amount of C 14 decreases After death C 12 remains constant The amount of C 14 decreases

Scientists can use this information to determine the age of carbon containing artifacts • Scientists can use this information to determine the age of carbon containing artifacts • Carbon-14 Dating

C-14 dating can only be used on something that was previously alive C-14 dating can only be used on something that was previously alive

Scientists use the elements lead (Pb) and Uranium (U) to date rocks samples. Scientists use the elements lead (Pb) and Uranium (U) to date rocks samples.

Meteor crater, Arizona Meteor Crater Video -- Killer Asteroid -National Geographic Meteor crater, Arizona Meteor Crater Video -- Killer Asteroid -National Geographic