LEARNING GOAL 5: EXAMINE THE USES AND EFFECTS OF NUCLEAR RADIATION ON HUMANS OR OTHER ORGANISMS.

Energy Unit

All living things contain living cells. We have many different types of cells which perform different functions including:

Skin cells. Red blood cells (they transport oxygen around the body) White blood cells (they fight infection). Nerve cells. Muscle cells. Brain cells.

Radiation can kill living cells or change the nature of living cells.

Radiation may be absorbed by the medium it passes through.

The Effects of Ionising Radiation

Ionising radiation can kill or change the nature of living cells.

The effects of the damage inflicted by the ionising radiation may:

be severe and cause immediate effects, or not become apparent for a long time.

The biological effect of radiation depends on:

The type of radiation. The type of body tissue or body organ that absorbs the radiation. The total amount of energy absorbed.

Effects of Radiation

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Somatic Damage Damage to the

organism itself Genetic Damage

Damage to an organisms gene that would affect future generations.

Radiation Causes Ionizations of:

ATOMSwhich may affect

MOLECULESwhich may affect

CELLSwhich may affect

TISSUESwhich may affect

ORGANSwhich may affect

THE WHOLE BODY

Direct Effect

Damage to DNA from ionization.

Indirect Effect

Radiation interacting with the water in a cell, rather then the DNA. Could lead to the braking of bonds in the

water molecule that could lead to toxic substances.

Ionizing radiation induces direct

DNA damage and indirect damage

through the radiolysis of

water.

Morgan W F , Sowa M B PNAS 2005;102:14127-14128

Short-Term Effects of Radiation

Short-term effects usually occur when there’s a large amount of exposure to radiation.

Effects of Short-Term Exposure

Dose (rem) Clinical Effect

0-25 Nondetectable

25-50 Temporary decrease in white blood cell counts

100-200 Strong decrease in white blood cell counts

500 Death of half the exposed population within 30 days after exposure.

rem – a unit invented to indicate the danger radiation poses to humans.

Long-Term Effects of Radiation

These effects take longer to become apparent and can be caused by much lower levels of radiation.

Uranium miners tended to get lung cancer due to breathing in gases which emitted alpha particles.

People who painted the dials of clocks with luminous paint developed one cancer from using their lips to make points on the brushes.

One of the most important long-term effects of radiation is that of cancer in various parts of the body.

High Dose Effects

Dose (Rad) radiation absorbed dose

Effect Observed

15-20 Blood count changes in a group of people.

50 Blood count changes in an individual.

100 Vomiting (threshold)

150 Death (threshold)

320-360 LD 50/60 with minimal care

480-540 LD 50/60 with supportive medical care

1,100 LD 50/60 with intensive medical care (bone marrow transplant)

More than 2,000 rad:Death is a certainty. At doses above 5,000 rad, the central nervous system (brain and muscles) can no longer control the body functions, including breathing and blood circulation. Everything happens very quickly. Death occurs within days or hours. Nothing can be done, and medical care is for comfort only.

1,000 to 2,000 rad:The probability of death increases to 100% within one to two 2000 rad weeks. The initial symptoms appear immediately. A few days later, things get very bad, very quickly since the gastrointestinal system is destroyed. Once the GI system ceases to function, nothing can be done, and medical care is for comfort only.

150 to 1,100 rad:Severe blood changes will be noted and symptoms appear immediately. Approximately two weeks later, some of those exposed may die. At 300-500 rad, up to one half of the people exposed will die within 30 days without intensive medical attention. Death is due to the destruction of the blood forming organs. Without white blood cells, infection is likely. At the lower end of the dose range, isolation, antibiotics, and transfusions may provide the bone marrow with time to generate new blood cells, and full recovery is possible. At the upper end of the dose range, a bone marrow transplant may be required to produce new blood cells.

50 to 150 rad:Slight blood changes including temporary drop in production of new blood cells will be noted and likely symptoms of nausea, fatigue and vomiting for one or two days.

5 to 50 rad:Slight blood changes may be detected by medical evaluation

Less than 5 rad:No immediate observable effects

Exposure Source

Millirems

Natural: Radon Other

200100

Occupational 0.90

Nuclear Fuel Cycle

0.05

Consumer Products

5-13

Environmental Sources

0.06

Medical:

Diagnostic X-rays

Nuclear Medicine

39

14

Approximate Total

360

Uses of Radioactive Substances

Industry Used to measure the thickness

of materials and to detect defects in metals and materials.

Power space craft. Clean toxic pollutants. Improve food production.

Everyday Uses Smoke Detectors

Rely on tiny radioactive source to sound the alarm when it sense smoke form a fire.

Nonstick pans Treated with radiation to ensure that the coating

sticks to the surface.

Everyday Uses

Watches and Clocks Modern watches and clocks sometimes use a small

quantity of hydrogen-3 (tritium) or promethium-147 as a source of light. Older (for example, pre-1970) watches and clocks used radium-226 as a source of light.

Ceramics Ceramic materials (for example, tiles, pottery) often

contain elevated levels of naturally occurring uranium, thorium, and/or potassium.

Glassware Antique glassware with a yellow or greenish

color, can contain easily detectable quantities of uranium.

Cosmetics, Hair Products, Contact Lenses Sterilized with radiation to remove irritants and allergens.

Everyday Uses

Gas Lantern Mantles While it is less common than it once was,

some brands of gas lantern mantles incorporate thorium-232.

Antique Radioactive Curative Claims In the past, primarily 1920 through 1950, a

wide range of radioactive products were sold as cure-alls.

For example, radium-containing pills, pads, solutions, and devices designed to add radon to drinking water.

Food Irradiation

Food irradiation is a method of treating food in order to make it safer to eat and have a longer shelf life.

Medical Uses

Nuclear Power Nuclear reactors are devices that

control fission reactions producing new substances and energy.

Steam is created from the heat

(energy) produced. The steam turns

the turbines to produce electric energy.

A Fission ReactorA Fission Reactor

Copyright © Houghton Mifflin Company

19-30

Figure 19.7: Schematic of the reactor core.

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Nuclear Power

 

Advantages•Nuclear power costs about the same as coal, so it's not expensive to make.  •Does not produce smoke or carbon dioxide, so it does not contribute to the greenhouse effect. •Produces huge amounts of energy from small amounts of fuel. •Produces small amounts of waste. •Nuclear power is reliable.

Disadvantages •Although not much waste is produced, it is very, very dangerous. •The waste must be sealed up and buried for many years to allow the radioactivity to die away.  •Nuclear power is reliable, but a lot of money has to be spent on safety - if it does go wrong, a nuclear accident can be a major disaster. •people are increasingly concerned about this - in the 1990's nuclear power was the fastest-growing source of power in much of the world. Now, in 2005 it's the second slowest-growing.

Weapons

A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion.