Lecture 2: Nuclear Terrorism Flashcards
What is nuclear terrorism?
The use or threat to use nuclear material, nuclear fuel, or radioactive products for acts of terrorism.
What does an atom consist of?
Nucleus (protons + neutrons) and electrons.
What are isotopes?
Atoms with the same number of protons but different numbers of neutrons.
What is radioactivity?
The process where unstable isotopes emit radioactive particles or energy to form stable isotopes.
Who coined the term radioactivity?
Marie Curie.
What was a significant event related to nuclear power in 2011?
Fukushima nuclear disaster.
What elements did Marie Curie discover?
Radium and polonium.
What are the three types of radiation?
- α particles
- β particles
- γ rays
What is ionizing power?
The ability of a radioactive particle to ionize another molecule.
What is the charge and composition of an α particle?
- Charge: +2
- Two protons and two neutrons.
- Symbol: Helium (4/2He)
What is the charge and composition of a β particle?
- Charge: -1
- One electron.
What is a γ ray?
An extremely high-energy photon, having no mass and no charge.
What factors affect the hazards of radioactivity?
- Length of time of exposure
- Type of radiation
- Dose of radiation received
- Source of radiation (external or internal)
What is half-life?
The time required for the amount of radioactive material to decrease by one-half.
Compare the three types of radiation
- α: Highest ionization ability, least penetrating
- β particles
- γ rays: Lowest ionization ability, most penetrating
Describe the medical applications of nuclear radiation
- γ rays: large penetrating power to reach detector, low ionization power to minimize damage to body tissues
- α or β emitters implanted into a tumor, directly exposing cancer cells to the radioisotope (low penetration power)
- Use radioactive isotopes with short half-lives to minimize total exposure to radiation
- E.g. Radioactive iodine therapy to treat thyroid cancer
What is carbon-14 dating used for?
Determining the age of recent human remains.
What is the principle of nuclear reactors?
- Reactor core: Generates heat
- Steam generation system: Converts water into steam → pressure spins turbine fan blades → producing electricity
- Cooling tower system: Steam condenses back to water, pumps cooling water from and back to river
What initiates the fission of uranium-235 in nuclear reactions?
- A neutron strikes the uranium-235 nucleus.
- Splits into barium, krypton, three addtional neutrons, and heat
- Chain reaction
- The fission of one atom of U-235 generates 3.24 × 10−11 J energy.
- The fission of one kg of U-235 generates 83.14 × 1012 J energy.
- The released energy can be calculated from the mass defect (Mass difference between the products and reactants of the nuclearreaction) of the nuclear fission
How is nuclear fission controlled?
- Purpose: Prevent excess heat generated to prevent reactor core melt down
- Done by: Control rods (neutron-absorbing boron pr hafnium)
What is critical mass in nuclear weapons?
The smallest amount of nuclear material needed for a nuclear chain reaction.
What is a dirty bomb?
A conventional bomb with radioactive materials added to spread contamination upon detonation.
What is a Geiger counter?
A device used to detect and measure ionizing radiation.
How does a Geiger counter work?
It detects ionizing radiation by creating an electric pulse when high-energy particles collide with gas in a tube.
What is neutron activation analysis?
It involves bombarding an element with neutrons to create energetically excited isotopes that emit gamma rays for identification.
- Second gamma ray released during beta decay
What is one advantage of Neutron Activation Analysis?
- allows trace element analysis
- does not destroy the sample
- useful for art and historical artifacts
What must balance in nuclear equations?
The mass numbers and atomic numbers must add up to the same value on both sides
This is essential for the conservation of mass and charge.
What is required for a chain reaction to occur in nuclear reactions?
Critical mass
This is the minimum amount of fissile material needed to maintain a chain reaction.
True or False: A beta decay involves the release of a gamma ray.
True
A second gamma ray can be released during the beta decay of the nucleus.
What is the primary hazard associated with radiation?
Ionizing power
Ionizing radiation can damage living tissue and DNA.
What are the two basic designs for nuclear weapons?
Gun-Type
- two subcritical masses of uranium-235 are brought together
- uses conventional explosives
- initiates a nuclear chain reaction and explosion
- e.g. “Little Boy” Hiroshima 1945
Implosion
- compresses plutonium core
- uses high explosives
