Nuclear Power

Question 1

what are 4 major sources of public exposure to natural radiation?

Answer 1

1. cosmic radiation (eg. sun)- fast-moving particles from space
2. terrestrial radiation (eg minerals like uranium)
3. inhalation (gases/ minerals)
4. ingestion (eg. groundwater running through radioactive minerals)

*most exposure is through inhalation

Question 2

radiation exposure can damage DNA. What are 3 things this can lead to?

Answer 2

1. nothing (cells repair properly)
2. cell dies because DNA is too damaged
3. the cell repairs itself improperly (or doesn’t repair fully) b/c of the damaged DNA= risk of cancer

Question 3

Risks from radiation sickness:
- Brain:
- Thyroid Gland:
- Lungs:
- GI Tract:
- Bone marrow/ blood vessels:
- Skin:

Answer 3

• Brain: seizures
• Thyroid Gland: absorbs radioactive iodine= thyroid cancer risk
• Lungs: inflammation, scarring, possible cancer risk
• GI Tract: internal bleeding
• Bone marrow/ blood vessels: loss of white blood cells= risk of infection
• Skin: burns from acute exposure

Question 4

what was the effect on the following organisms after the nuclear disaster in Ukraine?
- Moose:
- Trees:
- Birds:

Answer 4

• Moose= nothing
• Trees= died
• Birds= abnormalities

Question 5

What is Nuclear Fission? Nuclear Power?

Answer 5

Nuclear Fission= the splitting apart of atomic nuclei

Nuclear Power= the forcing together of atomic nuclei (opposite of nuclear fission)

Question 6

moderator=

Answer 6

substance used to slow down neutrons bombarding the uranium (nuclear fuel), usually water or graphite.
Also used to transfer heat energy (mixed with the fuel)

Question 7

control rods=

Answer 7

used to absorb excess neutrons to slow down reactions, usually made of a metal (silver, cadmium)
= reactions don’t happen too fast (prevents further fission)

Question 8

containment structure=

Answer 8

building housing the reactor, core, reactor vessel, and steam generator.
Usually super thick concrete and steel

Question 9

How does a “Standard” Pressurized Water Reactor (PWR) work?

Answer 9

Ur235 (in the reactor vessel) has a neutron added to it
- this forms Ur236 (excited form) which splits and produces energy

Question 10

What’s the biggest advantage of a CANDU type reactor over a PWR?

Answer 10

PWR must be shut down to refuel
CANDU can be refueled (w Ur) without shutting it down, and the process is overall more efficient

Question 11

How do CANDU type reactors work?

Answer 11

fission inside the reactor (Ur atoms split, releasing energy and radiation)

Heavy water is used as a moderator and coolant

Question 12

CANDU reactors:
Function is similar to PWR, except:

• safer b/c less _____
• fewer ___ absorbed by heavy water
• can use ____ uranium as fuel
• The excess ___ can absorb a neutron, to form ___, which can also be used as fuel
• can be ___ while operating at full power

Answer 12

• pressurized
• neutrons
• unenriched
• U238, Pu239
• refueled

Question 13

T/F
U of A had a nuclear reactor (for research purposes) until Aug 2017!

Answer 13

true
SLOWPOKE-2

Question 14

What are the top 4 methods of mining Uranium?
(most-least used)

Answer 14

1. In-Situ leaching
2. Underground Mining
3. Open Pit Mining
4. Heap leaching

Question 15

Explain the process of mining uranium to using it for energy

Answer 15

1. uranium extracted from mines and crushed up at mills
2. uranium oxide is processed to get:
3. uranium hexafluoride is enriched to get:
4. enriched UF6 undergoes fuel fabrication to get:
5. uranium fuel (U238 or U236)
6. fuel is taken to the power plant, used to generate electricity

Question 16

T/F
Canada has the largest % of Uranium production in the world

Answer 16

true!
(sask)
produces 1/3 of the world’s U

Question 17

Where’s the largest Uranium mine in the world?

Answer 17

McArthur River, Saskatchewan (underground mine)

Question 18

give an example of an accident involving Uranium tailings

Answer 18

drinking water contamination in Navajo Nation, USA from Uranium tailing ponds (during cold war)

Question 19

What happens to uranium tailings?

Answer 19

stored in water to prevent oxidation & contain radiation
- excess water is treated as nuclear waste
- must be maintained properly, leaks are very dangerous

Question 20

give some examples of radioactive waste components

Answer 20

• spent fuel rods
• used PPE
• old equipment
• contaminated soil and water

Question 21

Waste is categorized by its radioactivity, what are the categories?

Answer 21

1. Low level: items exposed to radiation that require <300 yrs to lose radioactivity
2. Intermediate Level: items exposed to radiation that require >300 yrs to lose radioactivity
3. High level: spent nuclear fuel (huge amount of radioactivity)

Question 22

Low and Intermediate level waste makes up ___% of nuclear waste. How/ where is it stored?

Answer 22

98%
- producers of the waste are responsible for its disposal
1. store on site
2. when can’t store on site, pay Canadian nuclear laboratories to take care of it

Question 23

how long do medical isotopes usually take to decay?

Answer 23

a few days

Question 24

How is high-level radioactive waste stored?

Answer 24

Two-step process:

1. wet storage
   - initial storage after use: held in water tanks at power plants for 7-10 yrs (makes it safer to transport later)
2. dry storage
   - long-term storage in concrete canisters/steel dry storage (up to 100yrs)

Question 25

How do we move high-level radioactive waste?

Answer 25

done robotically b/c we can't touch it - in a container that can withstand drops, extreme heat, and deep water

Question 26

How do you store radioactive waste after the 100yrs in the dry storage containers?

Answer 26

we're still figuring it out need to figure something out soon!

Question 27

what's a proposed solution for storing radioactive waste for a very long time?

Answer 27

bury it! = deep geological repository - 500m deep, very well insulated, durable, and monitored

Question 28

what kind of rocks would the deep geological repository be in? why?

Answer 28

crystalline (metamorphic) or sedimentary rocks because they're the least permeable (surface is protected from the radiation)

Question 29

why are all of Canada's nuclear plants in the east and not the west?

Answer 29

tectonic activity in the west is hazardous for nuclear accidents (caused by earthquakes etc)

Question 30

describe an example of a deep geological repository project that was started

Answer 30

Yucca Mountain, Nevada - construction began in 2008, shut down in 2010 - worries about groundwater contamination -"Not in my backyard"

Question 31

In Canada, we're down to __ locations that seem suitable for a deep geological repository (list the locations)

Answer 31

2 -Ignace, Ontario - South Bruce, Ontario

Question 32

How many nuclear power accidents (&fatalities) have there been in Canada? USA?

Answer 32

Canada: 10 accidents, no fatalities US: 56 accidents, 12 fatalities

Question 33

What's the difference between an incident and an accident? At what level (of international nuclear event scale) does it become an accident?

Answer 33

incident= no significant harm or death accident= significant harm or deaths incidents= level 1-3 accidents= level 4-7

Question 34

Name the 2 nuclear power accidents that had widespread, measurable environmental damage (and dates)

Answer 34

1. Chernobyl (April 1986) 2. Fukushima Daiichi (March 2011)

Question 35

What caused the accident in Fukushima Daiichi?

Answer 35

- plant was damaged by a tsunami (after an eq) in March 2011 - disabled generators cooling, causing them to overheat - lead to 3 reactor meltdowns, and one wet storage pool overheating fuel rods shouldn't have been stored in the same place as reactions!

Question 36

Any fatalities caused by Fukushima accident?

Answer 36

not yet - fatalities from cancers expected to come

Question 37

List some environmental impacts of the Fukushima accident

Answer 37

- high levels of radioactive isotopes measured in the waters off the coast on Fukushima (short half-lives, but some are continuously being leaked b/c of structural damages to reactors) - ocean currents moved contaminated waters throughout the whole pacific ocean - high radiation levels measured in bluefin tuna (they're migratory- transporting this radiation) - scientists are still trying to figure out the impacts

Question 38

How could the Fukushima accident have been avoided? 2 ways

Answer 38

1. fail-safe power backups for all cooling devices - now required b/c of this accident 2. don't build nuclear power plants in geologically active areas!

Question 39

What's the worst nuclear accident in history? How did it happen?

Answer 39

Chernobyl, Ukraine - workers turned off safety systems during a test, then a power surge occurred

Question 40

How many fatalities from Chernobyl?

Answer 40

49 direct fatalities + 1000s of related cancer cases

Question 41

A ____ at the Chornobyl plant was active for 10 days, and ___ spread throughout Europe The area in and around Chernobyl is still ____ and ____

Answer 41

fire, ash irradiated, inhabitable

Question 42

what was done in chernobyl to try and contain radioactivity after the accident?

Answer 42

the plant was immediately covered up by a huge building/ wall that went over the whole thing

Question 43

How have forests around Chernobyl been impacted by the accident?

Answer 43

"The Red Forest" - trees have died and are not decaying b/c the radioactivity has killed decomposers - a huge forest fire the next year destroyed the rest of the forest and released more radioactivity

Question 44

How have local wildlife been impacted by Chernobyl?

Answer 44

- evidence of some defects, which are selected against - some wildlife populations are now thriving b/c of no humans - some abnormalities in birds - effects of radiation smaller in wildlife than in humans

Question 45

Which organisms actually like radiation?

Answer 45

- yeast - fungi they use it as an energy source! - new species like this are being discovered in areas like Chernobyl

Question 46

Name and briefly describe 2 smaller nuclear accidents that occurred in Canada (Chalk River, Ontario)

Answer 46

1. NRX (national research experimental) - overheated b/c cooling system was disabled for a test 2. NRU (national research universal) - fire damage

Question 47

What are 3 other nuclear concerns? give examples

Answer 47

1. leakage - eg Vermont nuclear power plant= not properly maintained, and radioactive isotopes are leaking into the area 2. Nuclear bombs and weapon testing - eg. Hiroshima, secret weapon testing releasing unknown amounts of radiation 3. downwinders = civilians unknowingly being exposed to radiation from nuclear weapon testing= cancer (mainly in Arizona, Utah, Nevada)