Physics/Global Studies 280


Nuclear Weapons, Nuclear War, and Arms Control

Frederick K. Lamb

2005 Midterm Examination Questions and Answers

Question 1 | Question 2 | Question 3 | Question 4 | Question 5 | Question 6

1. Physics of Nuclear Weapons [20]

(a) Sketch the curve of binding energy per nucleon from A=1 to A=240. [4]

Refer to class notes, section "Nuclear Weapons", powerpoint slide number 20.

(b) Explain, using this curve, why nuclear weapon designers are interested in very light and very heavy nuclei. [4]

Very light nuclei combine easily and release energy, very heavy nuclei split easily and release energy

(c) What is a fissile nuclide? What is a fissionable but non-fissile nuclide? [4]

fissile nuclide - can be fissioned by a neutron of any energy

fissionable but not fissile nuclide - fissionable only by neutrons above a threshold energy

(d) What fissile isotope of uranium is most common in nature? [3]

uranium-235

(e) Define the following special nuclear materials: [5]

low-enriched-uranium - contains less than 20% U-235
highly-enriched uranium - contains greater than 20% U-235
weapons-grade uranium - contains greater than 80% U-235
reactor-grade plutonium - contains greater than 19% Pu-240 and heavier isotopes
weapons-grade plutonium - contains less than 7% Pu-240 and heavier isotopes

Return to Top

2. Nuclear Weapon Designs [20]

a) Draw a schematic diagram of an unboosted, implosion-type fission weapon. [8]

Refer to class notes, section "Nuclear Weapons", powerpoint slide number 53.

b) Label the main components in your diagram by naming them and drawing arrows from the names to the components. [4]

Refer to class notes, section "Nuclear Weapons", powerpoint slide number 53.

c) Describe in a single sentence the function of each of the main components. [4]

The chemical HE lenses compress the fissile material into a supercritical configuration.
The tampers holds the fissile material together longer, so that there will be more generations in the reaction.
The reflector holds in neutrons that would otherwise escape.
The fissile material is the fuel for the explosion.
The initiator starts the chain reaction by supplying neutrons once a supercritical configuration is achieved.

d) What is a supercritical configuration of fissile material? [4]

A supercritical configuration of fissile material has a neutron multiplacation factor greater than one.
(also acceptable): The number of neutrons is greater in each successive generation.
(also acceptable): The number of fissions is greater in each successive generation.

Return to Top

3. Effects of Nuclear Explosions [20]

a) List the four principal effects that would be experienced by a person located 3 miles from the airburst produced by a 1 Mt thermonuclear weapon, in the order they would be experienced. Describe the cause of each effect and its main consequence. [8]

  1. Prompt nuclear radiation.
    -produced by fissioning or fusing nuclear material
    -irradiates surrounding people and materials
  2. Heat / Thermal Pulse
    -thermal electromagnetic radiation (from fireball)
    -causes fires/burns
  3. Blast Wave
    -strong shockwave produced by rapidly expanding fireball
    -crushes and blows away people and structures
  4. Residual nuclear radiation
    -weapons debris and particles from the surroundings made radioactive by the bomb (fallout)
    -causes radiation sickness
b) What is a conflagration? [2]

A conflagration is a ring of fire that spreads outward from the ignition point, leaving burned out area behind.

c) What is a firestorm? [2]

A firestorm is an intense central fire that creates a strong updraft and sucks in new fuel continuously.

d) Describe quantitatively the electromagnetic pulse produced by a nuclear weapon exploded in the upper atmosphere. What is its duration in seconds? What effect would it have on the U.S.? [3]

EMP is a short (nanosecond) pulse of electromagnetic radiation produced by a nuclear explosion. Such an EMP would destroy electronics and disable power grids.

e) Describe the characteristic temporal behavior of the visible light produced by a nuclear explosion in the lower atmosphere. What causes this effect? Why is this effect important? [3]

A nuclear explosion produces a "double flash", because of a temporary opacity in the fireball. This double flash is very nearly unique to nuclear explosions, and is thus useful for detecting weapons tests.

f) The NORAD command center is located deep inside Cheyenne Mountain. Could it survive a direct nuclear strike? (Yes or no.) [2]

No.

Return to Top

4. Nuclear Arms Race and Nuclear Proliferation [20]

a) In what year did the U.S. first test a nuclear weapon? [1] 1945

b) In what year did the Soviet Union first test a nuclear weapon? [1] 1949

c) Which U.S. president ordered a crash program to develop an H-bomb? [1] Truman

d) In what year? [1] 1950

e) Which country first used a nuclear weapon in warfare? [1] USA

f) In what year? [1] 1945

g) What is a 'dual-use' technology in the context of nuclear weapons? [4]

A technology that could be used either for peaceful civilian purposes or for developing, testing, and manufacturing nuclear weapons.

h) Name two countries that once had nuclear weapons but gave them up. [2]

South Africa, Belarus, Kazakhstan, or Ukraine

i) Name two countries that received uranium enrichment technology from Pakistan via the black market network linked to A.Q. Khan. [2]

Iran, Libya, or North Korea

j) In February 2005, a state that has for several years been suspected of having nuclear weapons officially stated that it has them. Which is this state? [1]

North Korea

k) Which nuclear arms control treaty will be reviewed at a May 2005 conference of its signatories? Name two of the major issues that will be discussed. [5]

The NPT (Nuclear Non-Proliferation Treaty). The issues are: reporting, negative security assurances, verification, nuclear energy, non-strategic (tactical) nuclear weapons, the organization to prohibit nuclear weapons, nuclear weapons free zones, NGO participation.


Return to Top

5. Nuclear Terrorism [30]

a) What is nuclear terrorism? (Define it in terms of the attacker and the target.) [4]

Nuclear Terrorism involves a non-state attacker, who uses nuclear weapons to attack innocent civilians with the purpose of creating terror.

b) List four methods that could be used to smuggle a nuclear device into the U.S. [8]

Ship, barge, civilian aircraft, truck, backpack, or shipping container.

c) List and define the three crucial policies Allison argues must be implemented to deny terrorists access to nuclear weapons or materials (Allison's "three no's") and give a specific example of the application of each policy. [9]

  1. No Loose Nukes: All existing nuclear weapons must be secured adequately. (e.g.: "gold standard" security measures that all nuclear weapons states must take to ensure that all their weapons are well guarded.
  2. No Nascent Nukes: No new uranium enrichment facilities should be built.
  3. No New Nuclear Weapons States: States should be dissuaded from pursuing nuclear weapons development, if they don't have them already.
d) List and define any three of the seven crucial initiatives Allison argues must be taken to prevent nuclear terrorism (Allison's "seven yeses") and give a specific example of how each initiative could be implemented. [9]

This part of the answer key was not available. The information is readily available in Nuclear Terrorism

Return to Top

6. Bombers and Missiles [40]

Answer the following questions in two or three sentences or phrases, as appropriate:

a) What was the U.S. nuclear Triad? [6]

The U.S. nuclear triad was the combination of land based ICBMs, submarine based ballistic missiles, and nuclear armed bombers.

b) Can a bomber be recalled after it has been sent toward a target? (Yes or no.) [2]

Yes

c) Can a cruise missile be recalled after it has been sent toward a target? (Yes or no.) [2]

No

d) What force keeps a cruise missile aloft? [2]

aerodynamic forces/lift

e) What type of engine powers a modern cruise missile? [2]

turbofan

f) To what does the term "stealth technology" refer? [6]

Stealth technology, in effect, makes an aircraft harder to detect by radar by minimizing its radar crosssection (the radar signal it produces.)

g) Which has a longer range: a cruise missile with fitted a nuclear warhead or a similar cruise missile fitted with a conventional warhead? Why? [6]

The cruise missile fitted with a nuclear warhead, because the nuclear warhead occupies less space and can thus accomodate more fuel (increasing its range).

h) What is the approximate range of a modern long-range cruise missile fitted with a nuclear warhead? [4]

3000 km.

i) List three technologies used to guide modern cruise missiles. (Write three phrases.) [6]

terrain contour matching, digital scene matching area correlation, optical sensors for terminal guidance, GPS, inertial guidance.

j) List two technologies used to guide modern ballistic missiles. (Write two phrases.) [4]

satellite signals (GPS), inertial guidance (gyroscopes), stellar (star trackers)


Return to Top