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1

 

Is nuclear energy clean?

 

 

No, there is radioactive waste.

2

 

Where is nuclear waste stored?

 

 

Yucca Mountain

3

 

Yucca Mountain

 

  • Located 80 miles NW of Las Vegas.
  • Waste is stored deep underground.
  • It is designed to be a long term storage facility.
  • Approved in 2002 by Congress.
  • Funding was terminated in 2011 (thanks to Harry Reid).
  • High probability that Yucca Mountain will continue.

4

 

Nevada Test Site

 

  • Located 65 miles NW of Las Vegas.
  • Above-ground and underground testing.
  • Testing from 1951 to 1992.
  • 1,021 nuclear detonations; 921 underground detonations.
  • Long-term health and environmental impacts.

5

 

Environmental Impacts of Testing Sites

 

  • Above-ground detonations blast radioactive materials into the air, which gets carried away by the wind and deposited, causing a nuclear fallout.
  • Underground detonations contaminate soil and water and blast giant caverns underground.
  • These areas remain contiminated to this day.

6

 

How bad are these testing sites?

  • Radiation levels are on the order of 100,000 times that of accepted levels.
  • The longer the isotopes survive, the greater the risks (isotopes can live up to 10,000 years!).
  • There is no "immediate" health threat.
  • Nevada is ranked as Low Priority for clean up.
  • Only 48 water wells are currently monitored.

7

 

Two types of isotopes:

  1. Stable Isotopes – Optimum ratio of neutrons and protons.
  2. Unstable Isotopes – Ratio of neutrons and protons is either too high or too low. The unstable isotope will change in a way to RESTORE the balance between neutrons and protons.

— RADIOACTIVE

8

 

 

Radiation Types

Alpha Particle (α) 

Beta Particle (ß)

Gamma Rays ( ɣ )

 

 

 

9

 

Alpha Particle

α

 

– Heavy (large, massive)

– Positive ( + ) electric charge

– Helium w/o electrons

– Alpha particles are emitted when the nucleus wants to get into a more STABLE environment (Alpha Decay)

– Alpha particles are TWO protons and TWO neutrons (which is helium, He, on the periodic table)

 

He

2

10

 

Beta Particle

ß

– Light

– Negative ( – ) electric charge

– Just an emitted electron

– Moves really fast

– Beta particles (electrons) are emitted from a neutron, and that neutron turns into a proton in order to stabilize the nucleus (Beta Decay)

0   e

–1

11

 

Gamma Rays

ɣ

– No mass

– Pure energy

– Can travel far distances

– EXTREMELY DAMAGING

 

ɣ

0

 

12

 

How much damage can alpha particles do to the human body?

They can only cause surface (external) damage. Alpha particles lack the energy to penetrate the skin.

If, however, the alpha particles are inhaled or swallowed, the internal tissues will be affected and the risk of cancer increases (specifically lung cancer).

13

 

How much damage can beta particles do to the human body?

Both acute and chronic health effects. Acute exposures are uncommon. Contact with a strong beta source from an abandoned industrial instrument is the type of circumstance in which acute exposure could occur. Chronic effects are much more common.

Chronic effects result from fairly low-level exposures over a long period of time. They develop relatively slowly (5 to 30 years for example). The main chronic health effect from radiation is cancer. When taken internally beta emitters can cause tissue damage and increase the risk of cancer.

14

 

How much damage can gamma rays do to the human body?

Because of the gamma ray's penetrating power and ability to travel great distances, it is considered the primary hazard to the general population during most radiological emergencies.

In fact, when the term "radiation sickness" is used to describe the effects of large exposures in short time periods, the most severe damage almost certainly results from gamma radiation.

15

 

How can we make alpha particles less dangerous?

 

 

Add 2 electrons to them so that they can become helium.

16

 

How can we make beta particles less dangerous?

 

 

We must slow the particles down and incorporate them into whatever atom we have.

17

 

How do we protect ourselves from alpha particles?

 

 

We must wear really thick clothing.

18

 

How do we protect ourselves from beta particles?

 

 

We must use a material that is sturdier than thick clothing, like a thin metal sheet.

19

 

How do we protect ourselves from gamma rays?

 

 

Wearing a thick, lead apron, like the ones the x-ray technicians put on you before taking your x-ray.

20

 

What makes a nucleus unstable?

The balance of protons and neutrons in a nucleus determines whether a nucleus will be stable or unstable. Too many neutrons or protons upset this balance, disrupting the binding energy from the strong nuclear forces making the nucleus unstable.

  • Electrostatic forces (ESF) 

– Positive ( + ) repels positive ( + )

  • Strong Nuclear Force (SNF) 

– Attractive force between nucleons (protons and neutrons)

– Felt over short distances, between 1 and 3 femto (f or 10-15).

– SNF > ESF

 

21

 

Short Distance

 

  • ​SNF > ESF (Strong Nuclear Force > Electrostatic Force).
  • 1 – 3 fm.
  • A strong nuclear force in which the proton and electron ATTRACT each other because of their short distance from each other.

​(Refer to the nuclei on the RIGHT in the attached image)

 

 

22

 

Farther Distance

 

  • ESF > SNF (Electrostatic Force > Strong Nuclear Force)
  • > 3 fm

(Refer to the nuclei on the LEFT in the attached image)

23

Anything that is (less than / greater than) lead is too (big / small) to sustain itself.

 

 

Anything that is GREATER THAN lead is too BIG to sustain itself.

24

 

Is helium (He) stable or unstable?

 

STABLE

SNF > ESF

25

 

Is uranium (U) stable or unstable?

 

UNSTABLE

ESF > SNF

26

 

Types of Radioactive Decay

  1. Alpha (α) Decay – Produces an alpha particle when the nucleus emits TWO protons and TWO neutrons (which makes helium).
  2. Beta (ß) Decay – Produces a beta particle when a neutron emits an electron in order to turn into a proton.

27

All elements with an atomic number of 82 and larger will undergo

_________ because they are too large.

 

Radioactive decay

28

 

(Light / Heavy) elements are the most stable with the same number of protons and the same number of neutrons.

 

Light elements are the most stable with the same number of protons and the same number of neutrons.

29

As elements get bigger, we need more _______ to stabilize the nucleus.

 

Neutrons

30

 

Half-Life Decay

Radioactive isotopes decay at different rates. The radioactive decay rate is measured in terms of a characteristic time, the half-life. They are constant and are NOT affected by external conditions.

The half-life of a radioactive material is the time required for half of the radioactive atoms to decay.

Example:

Radium-226 has a half-life of 1620 years. This means that half of any given specimen Ra-226 decays by the end of 1620.