PHYSICS 180

FINAL EXAM

 

Name _________________________________________

ID No. _______________________

 

 

• This is a closed book examination of 120 minutes duration.

• Answer all 10 questions. All count equally (20 points each).

• Write your answers in the space provided on these pages.

If you need more room, write on the back of the page.

For full credit on definitions, give numbers where appropriate.

 

 

SCORES

 

  1. ______

  2. ______

  3. ______

  4. ______

  5. ______

  6. ______

  7. ______

  8. ______

  9. ______

10. ______

 

 

TOTAL ______

 

1. Nuclear Physics

Define 'fissionable nuclide' and name two. [5 points]

 

 

 

 

 

 

 

 

 

Define 'fissile nuclide' and name two. [5 points]

 

 

 

 

 

 

 

 

 

Define 'critical mass'. What is the critical mass of a bare sphere of 100% Pu-239? About how large would a sphere of Pu-239 with this mass be? [5 points]

 

 

 

 

 

 

 

 

 

 

What is the difference between reactor-grade and weapon-grade plutonium? Can a weapon made of reactor-grade plutonium be made to explode? [5 points]

 

 

 

 

 

2. Fission Weapons

a) Shown here is a schematic diagram of an unboosted, implosion-type fission weapon. Indicate on the diagram the locations of the following key components:

• Initiator

• Chemical high explosive lenses

• Weapon-grade fissile material

• Tamper

[8 points]

 

b) Describe briefly the roles of each of these four components. [12 points]

Initiator:

 

 

 

 

Chemical high explosive lenses:

 

 

 

 

Weapon-grade fissile material:

 

 

 

 

Tamper:

 

3. Weapon Effects

Give brief (one or two sentence) definitions of the following terms [10 points]

• Air burst

 

 

• Surface burst

 

 

• Fireball

 

 

• Blast wave

 

 

• Electromagnetic pulse (EMP)

 

 

In what order would the following effects be experienced by a person located 3 miles from the center of a 1 Mt airburst: fallout, thermal flash, blast wave, prompt nuclear radiation.
[4 points]

 

 

Give brief (one or two sentence) definitions of the following terms [6 points]

• Rad

 

 

 

• Relative biological effectiveness (RBE)

 

 

 

 

• Protection factor

 

4.  US-USSR Nuclear Arms Race

Four key technological developments in the US-USSR nuclear arms race are listed below. Choose three developments and

• state the country that first tested or deployed the technology

• give the approximate date that the United States tested or deployed the technology

• give the approximate date that the Soviet Union tested or deployed the technology

• describe in one or two sentences the significance of the test or deployment

[Dates within a year of the actual dates are adequate.]

 

Deployed sizable numbers of SLBMs [5 points]

 

 

 

 

 

 

 

Deployed sizable numbers of MIRVed missiles [5 points]

 

 

 

 

 

 

 

 

Tested a true thermonuclear weapon [5 points]

 

 

 

 

 

 

 

 

Deployed sizable numbers of ICBMs [5 points]

 

 

 

 

5.  Limitations on Nuclear Testing

Three treaties that limit nuclear testing are listed below. For each treaty—

• Give the year the agreement was signed

• Name the parties to the agreement

• List the key provisions of the agreement

• Describe one way compliance with the agreement can be monitored

 

Limited Test Ban Treaty (LTBT) [6 points]

• 1963

• US, USSR, UK

• Bans explosive testing of nuclear weapons or devices in the atmosphere, underwater, or in space.

Monitoring methods-

• Satellite-based optical sensors

• Underwater acoustic sensors

 

 

 

Threshold Test Ban Treaty (TTBT) [8 points]

• 1974

• US, USSR

• Bans underground testing of nuclear weapons with yields greater than 150 kt

• Peaceful nuclear explosions are not covered

Monitoring methods-

• Seismic wave measurements

 

Peaceful Nuclear Explosions Treaty (PNET) [6 points]

• 1976

• US, USSR

• Bans underground peaceful nuclear explosions to yields greater than 150 kt

Monitoring methods-

• On-site shock wave measurements

• Seismic wave measurements

• Overhead satellite photography, radio inrtercepts, etc.

 

6.  Defenses Against Ballistic Missiles

a) Answer the following questions about the threat to the US and its allies posed by theater ballistic missiles. [8 points]

List the three "non-nuclear-weapon" or "undeclared-nuclear-weapon" states that already have or soon will have ballistic missiles with ranges greater than 1,500 km.

• Saudia Arabia

• India

• Israel

Which (if any) of these states are likely adversaries of the US or its allies? Why or why not?

• Probably none. Tensions may arise between India and the US from time to time, but are seem unlikely to lead to direct conflict.

Which (if any) potential adversaries of the US have or are likely to have ballistic missiles capable of reaching the US in the next 15 years?

• Russia and China are possible adversaries, but tensiosn seem unlikely to lead to direct conflict.

b) List and explain (in one or two sentences) two different possible goals of a defense against ballistic missiles. [4 points]

 

 

 

c) List two concrete examples of each of the following four possible approaches to defending against ballistic missile attack. [8 points]

Preventive measures—

 

 

Counterforce attack—

 

 

 

Passive defense—

 

 

 

Active defense—

7.  Anti-Ballistic Missile (ABM) Weapons

a) Point (lower-tier) anti-tactical ballistic missile (ATBM) weapon systems. [6 points]

List two examples of targets that could in principle be defended by an ATBM weapon system of this type.

 

Give one example of an existing or proposed US ATBM system of this type.

 

 

b) Area (upper-tier) anti-tactical ballistic missile (ATBM) weapon systems. [6 points]

List two examples of targets that could in principle be defended by an ATBM weapon system of this type.

 

Give one example of an existing or proposed US ATBM system of this type.

 

 

c) Answer the following questions in two or three sentences. [8 points]

What is the role of large phased-array radars in an ABM system?

 

 

 

What is the role of high-altitude interceptors in an ABM system?

 

 

 

What is the role of low-altitude interceptors in an ABM system?

 

 

 

How would real-time access to missile tracking data from space-based sensor platforms affect the capabilities of an ABM system? (Be specific.)

 

 

8.  Nuclear Proliferation–I

List the five nations that openly possess nuclear weapons (declared nuclear weapons states). Give the year in which each first exploded a nuclear device. [10 points]

 

 

 

 

List the three nations that are thought to have nuclear weapons or near-nuclear capability, even though they do not acknowledge having a nuclear weapons programs (de factor nuclear weapon states). [3 points]

 

 

 

Which de facto nuclear weapon state recently gave up its nuclear weapons and joined the Non-Proliferation Treaty regime? [1 point]

 

Give short (two or three sentence) definitions of the following terms. [6 points]

Enrichment—

 

 

 

 

 

 

 

Reprocessing—

 

 

 

 

 

 

 

Horizontal proliferation—

 

 

9.  Nuclear Proliferation–II

What is the greatest single obstacle that a potential nuclear proliferator must overcome?
[2 points]

 

 

Signatures of nuclear materials acquisition and weapon fabrication [10 points]

List two actions that would indicate a country is acquiring or trying to acquire weapon-usable nuclear materials.

 

 

 

List three actions that would indicate a country is fabricating or trying to fabricate nuclear weapons.

 

 

 

 

 

 

 

List two new technologies that could make production of weapon-usable materials easier and explain how they work in a sentence or two. [6 points]

(i)

 

 

 

(ii)

 

 

 

Costs of nuclear weapons programs [2 points]

(i) What is the approximate overall cost of an overt nuclear weapon program capable of producing one bomb per year, according to the OTA?

 

 

(ii) What is the approximate minimum overall cost of a covert nuclear weapon program capable of producing one bomb per year, according to the OTA?

10.  Non-Proliferation Treaty (NPT)

The Non-Proliferation Treaty divides treaty signatories into nuclear-weapon states and non-nuclear-weapon states.

a) What are the major restrictions on the nuclear-weapon states, under the terms of the treaty? [4 points]

 

 

 

 

 

b) What are the major obligations of the nuclear-weapon states, under the terms of the treaty? [4 points]

 

 

 

 

 

c) What are the major restrictions on the non-nuclear-weapon states, under the terms of the treaty? [4 points]

 

 

 

 

 

 

d) Under the terms of the treaty, what conditions, if any, are there on the transfer or sale of nuclear reactors and related peaceful nuclear technologies to non-nuclear-weapon states? [4 points]

 

 

 

 

 

 

 

e) Under the terms of the treaty, after 25 years a conference must be held at which the treaty must be extended indefinitely, extended for another definite period, or cancelled. What is the status of this conference? [4 points]