Nuclear Energy

Question 1

What percentage of Canada’s electricity is generated from nuclear energy?

Answer 1

15%

Question 2

Where are most of the 19 reactors located?

Answer 2

Ontario

Question 3

What do the nuclear reactors in Canada provide?

Answer 3

commercial power

radioisotopes for nuclear medicine

research

Question 4

How do nuclear reactors generate energy?

Answer 4

Uranium atoms are split (fission) to create heat which
turns water to steam which
drives turbine generators to produce electricity

Question 5

Using nuclear power has reduced carbon dioxide

emissions by up to ____% in some countries

Answer 5

60

Question 6

What is an atom composed of?

Answer 6

A central nucleus consisting of positively charged protons,
and neutral neutrons

Negatively charged electrons around the nucleus

Question 7

What is nuclear fission?

Answer 7

a nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy

or

by radioactive decay.

Question 8

What is radioactive decay?

Answer 8

the conversion of mass into energy E-mc2

Question 9

How many J is 1 g of matter (according to E-mc2)?

Answer 9

9 X 1013 J

Question 10

What are two problems associated with nuclear energy generation?

Answer 10

Exposure to radioactive material

Long half-lives involved in radioactive decay (U-235 has a half-life of 700 million years)

Question 11

Name two of the worst nuclear power plant accident in history.

Answer 11

Chernobyl - Ukraine (1986)

Fukushima - Japan (2011)

Question 12

What happened in the Chernobyl nuclear plant disaster?

Answer 12

reactor core overheated causing a steam explosion

Question 13

What happened in the Fukushima nuclear plant disaster?

Answer 13

The reactor survived a magnitude 9.0 earthquake but

not the subsequent Tsunami

Question 14

How does natural uranium and freshly spent fuel rods (uranium after being in the reactor) compare in radioactivity?

Answer 14

Natural uranium is mildly
radioactive

freshly spent fuel rods are highly radioactive

Question 15

How is spent fuel from reactors stored?

Answer 15

spent fuel pools

Stored in spent fuel pools the rods are placed on racks and then submersed in water (good for radiation shielding and cooling) for a couple of decades until it is inert enough to move into dry casks.

Question 16

How long does spent fuel from reactors have to be stored?

Answer 16

thousand of years

spent nuclear fuel remains radioactive for thousands of years and must be safely stored
for that length of time.

Question 17

What types of radiation are there?

Answer 17

Alpha
Beta
Gamma

Question 18

Explain Alpha radiation

Answer 18

causes the most ionisation in its path and is most damaging but least penetrating

can be stopped by a piece of paper

Question 19

Explain Beta radiation

Answer 19

Beta is intermediate in effect

Stopped by a layer of clothing or a few mm of substance such as aluminium

Question 20

Explain Gamma radiation

Answer 20

Most penetrating

Stopped by several feet of concrete or a few inches of lead

Question 21

What does ionising radiation do to a person or object?

Answer 21

does not cause it to become radioactive

high energy radiation particles can ionize atoms and break chemical bonds within molecules

Question 22

How does the radiation we are exposed to harm our bodies?

Answer 22

directly kill cells

cause mutations to DNA (causing cancer)

if in very high doses can cause radiation sickness which is often fatal

Question 23

How do you measure radioactivity?

Answer 23

rate of radiation emission from a source

Becquerel (Bq)
Curie (Ci)

1 Bq = 27pCi

Question 24

How do you measure radiation energy?

Answer 24

Electron volts (eV)
6,200 bill MeV = 1 joule

Question 25

How do you measure radiation exposure?

Answer 25

The radiation dose absorbed by a person (that is, the amount of energy deposited in human tissue by radiation) is measured using the conventional unit rad or the SI unit gray (Gy).

The biological risk of exposure to radiation is measured using the conventional unit rem or the SI unit sievert (Sv)

Question 26

What is a recommended annual does of radiation?

Answer 26

0.05 Sv (50 mSv)

Question 27

What are the effects of larger doses of radiation at one time?

Answer 27

If very high Risk of death within days or weeks

Increased Risk of cancer later in life (5 in 100)

Question 28

What is radioactive decay?

Answer 28

the conversion of mass into energy E-mc2

Occurs naturally over-time (naturally occurring nuclear
reactions!)

It is the process by which a nucleus of an unstable
atom loses energy by emitting ionizing radiation

Question 29

What is half-life?

Answer 29

Amt of time it takes for half of the nuclei to decay

Follows mathematical principle of exponential decay

Question 30

What are the equations to understand for radiation decay (p. 45)?

Answer 30

Q = Qo(1 – r)t

Q = Qo(1/2)t/T

refer to p. 45 if unclear

Question 31

What are the equations to understand for radiation growth?

Answer 31

Q = Qo(1 + r)t

Q = Qo(2)t/T

Question 32

How do you calculate the amount of radioactive isotopes remaining?

Answer 32

Qt = Qo x (0.5)t/T
Qt = amount of radioisotope remaining
Qo = original amount of radioisotope
t = time
T = half-life of isotope

Question 33

How do you calculate the amount of radioactive isotopes remaining?

Answer 33

Qt = Qo x (0.5)t/T
Qt = amount of radioisotope remaining
Qo = original amount of radioisotope
t = time
T = half-life of isotope

Example p44
Radon gas has a half-life of 3.8 days.
If we start with 5 mg of Radon, how
much is left after 1 month (30 days)? much is left after 1 month (30 days)?
Qt = Qo x (0.5) t/T
Qt = ? mg
Qo = 5 mg
t = 30 days
T = 3.8 days 

Example
Calculate the percentage of strontium-90 remaining
after 280 years. Half-life of 28 years.
Qt = Qo x (0.5) t/T
Qt = ? %
Qo = 100%
t = 280
T = 28 years
Qt = 100 x (0.5)10 = 0.098%