“The World We Create”NATS 101Section 6

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02/02

UNIT 1: Energy Sources,

Conventional or Alternative?

Nuclear Energy

Ionizing RadiationIt has enough energy to affect the

structure of the atoms. Particularly, to remove electrons (ionize) and break

bonds in molecules.

Radioactivity

Some substances, such as uranium and plutonium, emit ionizing radiation spontaneously

(you don’t need to split them).

This property is called Radioactivity Geiger Counter

Identify common sources of ionizing radiation in your surroundings.

Make better judgments about the risks of exposure to different sources of ionizing radiations;

Evaluate the truthfulness and implications of statements about radioactive materials.

How much are we exposed?

True or False?1. Human senses can detect radioactivity.

2. Elements such as Uranium and Radium are radioactive, but others such as Carbon and Lead are not.

4. Radioactive waste has very high temperatures.

3. Cancer cells are more sensitive to radiation than healthy cells.

5. Smokers are exposed to a highly dose of radioactivity than non-smokers.

6. The human body naturally contains small quantities of radioactive substances.

7. Exposure to radioactive materials causes serious burns.

8. Radioactive materials glow in the dark.

Radioactive Decay

Radioactive isotopes are unstable and “decay” by emitting particles or energy. In this process, the

chemical nature of the atoms can change (they may lose or gain protons).

Radioactive decay can occur through three different types of processes, each of which

generates a different type of ionizing radiation.

Alpha decay

Beta decay

Gamma decay

Alpha Decay

What is emitted? What happens to the nucleus?

Beta Decay

=electron

What is emitted? What happens to the nucleus?

Gamma Decay

What is emitted? What happens to the nucleus?

Low Energy – Non-Ionizing

High Energy – Ionizing (changes structure of matter)

Low E- Non-Ionizing

Electromagnetic Radiation

High E- Ionizing

In Your Groups

List 3 - 4 ways you have been exposed to ionizing radiation today

(in the form of either waves or particles).

You have 2-3 minutes

Isotopes in NatureMost elements in nature are a mixture of isotopes. Some of them are radioactive,

although most of them are not.

Some Natural Radioisotopes

Name Symbol Abundance (%)

Hydrogen-3 H31 0.00013

Carbon-14 C146 Trace

Potassium-40 K4019 0.0012

Platinum-190 Pt19078 0.012

Thorium-232 Th23290 100

Uranium-238 U23892 99.28

Background Radiation• In our everyday lives, we are exposed to some amount of ionizing radiation.

• This amount varies by person, depending on your lifestyle and living conditions.

• Scientists call this type of radiation Background Radiation.

How Do We Measure Radiation?

Because of its effect on living tissue, the amount of ionizing radiation to which people are exposed over

time must be monitored.

In the US, the radiation dose is measured using two basic units:

RAD- measures the absorbed dose of radiation

REM- measures the ionizing effect on living organisms

Normal human exposures are measured in milirems 1 mrem = 0.001 rem

Your Annual Dose Calculate your individual annual ionizing- radiation dose (handout).

Compare your annual dose with the dose calculated by the other members of your team. Calculate the group average.

Compare the amount of radiation from natural sources (radon, cosmic, terrestrial, internal) to that from man-made sources?

You have 10 minutesTo convert your answer to rems from mrems:

divide your value by 1000.

Sources of Ionizing Radiation

US average yearly dose: 0.36 Rems.

Internal Sources

ThyroidIodine-131

LungsRadon-222

Uranium-238Plutonium-239

Krypton-85

MusclesPotassium-40Cesium-137

LiverCobalt-60

BonesRadium-226Strontium-90

Phosphorus-32Carbon-14

How Much Would It Take?

Dose Bodily Effect

0-25 rems No noticeable effect

25-50 Slight decrease in white blood cell count

50-100 Significant decrease in white blood cell count

100-200 Nausea, loss of hair

200-500 Hemmoraging, ulcers, possible death

>500 Death

Annual deaths from various sources (2003)

18,000

35,000

63,000

109,000

158,000

557,000

685,000

0 100,000 200,000 300,000 400,000 500,000 600,000 700,000 800,000

HIV and AIDS

Nuclear radiation

Alzheimer's

Accidents

Stroke

Cancer

Heart disease

Biological Damage from Radiation

Rapidly dividing cells, such as blood cells and sex cells, are more susceptible to radiation damage that are slowly dividing or non-dividing cells, such as nerve cells. Fetuses and children are more susceptible to radiation damage than are adults.

Tissue type

Most scientists assume that an increase in radiation dose produces a proportional increase in risk.

Dose

The more a given dose is spread out over time, the less harm it does.

Exposure time

The larger the body area exposed, the greater the damage.

Area exposed

The BenefitsMedical uses

Diagnosis: - Tracers- PET scans

Treatment:Cancer patients are

“shot” with a beam of radiation in a localized

area, killing most of the cells in the area.

“The average radiation dose to people living within ten miles of the Three Mile Island Nuclear Plant was 8 mrem, and no

more than 100 mrem to any single individual.” American Nuclear Society

“Some 350,000 people involved in the initial clean-up of the Chernobyl nuclear plant in 1986-87 received average total

body radiation doses of the order of 10 rems.”International Atomic Energy Agency

What is this telling you?What would your reaction be?

“The study of 120,000 Hiroshima survivors indicates that the risk of cancer increases linearly with the radiation dose. The dose at

1000 meters at Hiroshima is estimated at 400 rems.” Hyperphysics (on-line resource)

True or False?1. Human senses can detect radioactivity.

2. Elements such as Uranium and Radium are radioactive, but others such as Carbon and Lead are not.

4. Radioactive waste has very high temperatures.

3. Cancer cells are more sensitive to radiation than healthy cells.

5. Smokers are exposed to a highly dose of radioactivity than non-smokers.

6. The human body naturally contains small quantities of radioactive substances.

7. Exposure to radioactive materials causes serious burns.

8. Radioactive materials glow in the dark.

True or False?Human senses can detect radioactivity.

Elements such as Uranium and Radium are radioactive, but others such as Carbon and Lead are not.

Radioactive waste has very high temperatures.

Cancer cells are more sensitive to radiation than healthy cells.

Smokers are exposed to a highly dose of radioactivity than non-smokers.

The human body naturally contains small quantities of radioactive substances.

Exposure to radioactive materials causes serious burns.

Radioactive materials glow in the dark.