<< Chapter < Page Chapter >> Page >

A few small countries have built or are capable of building nuclear bombs, as are some terrorist groups. Two things are needed—a minimum level of technical expertise and sufficient fissionable material. The first is easy. Fissionable material is controlled but is also available. There are international agreements and organizations that attempt to control nuclear proliferation, but it is increasingly difficult given the availability of fissionable material and the small amount needed for a crude bomb. The production of fissionable fuel itself is technologically difficult. However, the presence of large amounts of such material worldwide, though in the hands of a few, makes control and accountability crucial.

Section summary

  • There are two types of nuclear weapons—fission bombs use fission alone, whereas thermonuclear bombs use fission to ignite fusion.
  • Both types of weapons produce huge numbers of nuclear reactions in a very short time.
  • Energy yields are measured in kilotons or megatons of equivalent conventional explosives and range from 0.1 kT to more than 20 MT.
  • Nuclear bombs are characterized by far more thermal output and nuclear radiation output than conventional explosives.

Conceptual questions

What are some of the reasons that plutonium rather than uranium is used in all fission bombs and as the trigger in all fusion bombs?

Got questions? Get instant answers now!

Use the laws of conservation of momentum and energy to explain how a shape charge can direct most of the energy released in an explosion in a specific direction. (Note that this is similar to the situation in guns and cannons—most of the energy goes into the bullet.)

Got questions? Get instant answers now!

How does the lithium deuteride in the thermonuclear bomb shown in [link] supply tritium ( 3 H ) as well as deuterium ( 2 H ) size 12{ {} rSup { size 8{2} } H} {} ?

Got questions? Get instant answers now!

Fallout from nuclear weapons tests in the atmosphere is mainly 90 Sr and 137 Cs , which have 28.6- and 32.2-y half-lives, respectively. Atmospheric tests were terminated in most countries in 1963, although China only did so in 1980. It has been found that environmental activities of these two isotopes are decreasing faster than their half-lives. Why might this be?

Got questions? Get instant answers now!

Problems&Exercises

Find the mass converted into energy by a 12.0-kT bomb.

0.56 g

Got questions? Get instant answers now!

What mass is converted into energy by a 1.00-MT bomb?

Got questions? Get instant answers now!

Fusion bombs use neutrons from their fission trigger to create tritium fuel in the reaction n + 6 Li 3 H + 4 He size 12{n+ rSup { size 8{6} } "Li" rightarrow rSup { size 8{3} } H+ rSup { size 8{4} } "He"} {} . What is the energy released by this reaction in MeV?

4.781 MeV

Got questions? Get instant answers now!

It is estimated that the total explosive yield of all the nuclear bombs in existence currently is about 4,000 MT.

(a) Convert this amount of energy to kilowatt-hours, noting that 1 kW h = 3 . 60 × 10 6 J size 12{1`"kW" cdot h=3 "." "60" times "10" rSup { size 8{6} } `J} {} .

(b) What would the monetary value of this energy be if it could be converted to electricity costing 10 cents per kW·h?

Got questions? Get instant answers now!

A radiation-enhanced nuclear weapon (or neutron bomb) can have a smaller total yield and still produce more prompt radiation than a conventional nuclear bomb. This allows the use of neutron bombs to kill nearby advancing enemy forces with radiation without blowing up your own forces with the blast. For a 0.500-kT radiation-enhanced weapon and a 1.00-kT conventional nuclear bomb: (a) Compare the blast yields. (b) Compare the prompt radiation yields.

(a) Blast yields 2.1 × 10 12 J size 12{2 "." "10" times "10" rSup { size 8{"12"} } `J} {} to 8.4 × 10 11 J size 12{8 "." 4 times "10" rSup { size 8{"11"} } `J} {} , or 2.5 to 1, conventional to radiation enhanced.

(b) Prompt radiation yields 6 . 3 × 10 11 J size 12{6 "." 3 times "10" rSup { size 8{"11"} } `J} {} to 2.1 × 10 11 J size 12{2 "." "10" times "10" rSup { size 8{"11"} } `J} {} , or 3 to 1, radiation enhanced to conventional.

Got questions? Get instant answers now!

(a) How many 239 Pu size 12{ {} rSup { size 8{"239"} } "Pu"} {} nuclei must fission to produce a 20.0-kT yield, assuming 200 MeV per fission? (b) What is the mass of this much 239 Pu size 12{ {} rSup { size 8{"239"} } "Pu"} {} ?

Got questions? Get instant answers now!

Assume one-fourth of the yield of a typical 320-kT strategic bomb comes from fission reactions averaging 200 MeV and the remainder from fusion reactions averaging 20 MeV.

(a) Calculate the number of fissions and the approximate mass of uranium and plutonium fissioned, taking the average atomic mass to be 238.

(b) Find the number of fusions and calculate the approximate mass of fusion fuel, assuming an average total atomic mass of the two nuclei in each reaction to be 5.

(c) Considering the masses found, does it seem reasonable that some missiles could carry 10 warheads? Discuss, noting that the nuclear fuel is only a part of the mass of a warhead.

(a) 1 . 1 × 10 25 fissions , 4.4 kg

(b) 3.2 × 10 26 fusions size 12{3 "." 2 times "10" rSup { size 8{"26"} } `"fusions"} {} , 2.7 kg

(c) The nuclearfuel totalsonly 6kg, soit isquite reasonablethat somemissiles carry10 overheads.The massof thefuel wouldonly be60 kgand thereforethe massof the10 warheads,weighing about10 timesthe nuclearfuel, wouldbe only1500 lbs.If thefuel forthe missilesweighs 5times thetotal weightof thewarheads, themissile wouldweigh about9000 lbsor 4.5tons. Thisis notan unreasonableweight fora missile.

Got questions? Get instant answers now!

This problem gives some idea of the magnitude of the energy yield of a small tactical bomb. Assume that half the energy of a 1.00-kT nuclear depth charge set off under an aircraft carrier goes into lifting it out of the water—that is, into gravitational potential energy. How high is the carrier lifted if its mass is 90,000 tons?

Got questions? Get instant answers now!

It is estimated that weapons tests in the atmosphere have deposited approximately 9 MCi of 90 Sr size 12{ {} rSup { size 8{"90"} } "Sr"} {} on the surface of the earth. Find the mass of this amount of 90 Sr size 12{ {} rSup { size 8{"90"} } "Sr"} {} .

7 × 10 4 g size 12{7 times "10" rSup { size 8{4} } `g} {}

Got questions? Get instant answers now!

A 1.00-MT bomb exploded a few kilometers above the ground deposits 25.0% of its energy into radiant heat.

(a) Find the calories per cm 2 size 12{"cm" rSup { size 8{2} } } {} at a distance of 10.0 km by assuming a uniform distribution over a spherical surface of that radius.

(b) If this heat falls on a person’s body, what temperature increase does it cause in the affected tissue, assuming it is absorbed in a layer 1.00-cm deep?

Got questions? Get instant answers now!

Integrated Concepts

One scheme to put nuclear weapons to nonmilitary use is to explode them underground in a geologically stable region and extract the geothermal energy for electricity production. There was a total yield of about 4,000 MT in the combined arsenals in 2006. If 1.00 MT per day could be converted to electricity with an efficiency of 10.0%:

(a) What would the average electrical power output be?

(b) How many years would the arsenal last at this rate?

(a) 4 . 86 × 10 9 W size 12{4 "." "86" times "10" rSup { size 8{9} } `W} {}

(b) 11.0 y

Got questions? Get instant answers now!

Questions & Answers

What is the difference between a principle and a law
the law is universally proved. The principal depends on certain conditions.
Dr
state Faraday first law
aliyu Reply
what does the speedometer of a car measure ?
Jyoti Reply
Car speedometer measures the rate of change of distance per unit time.
Moses
describe how a Michelson interferometer can be used to measure the index of refraction of a gas (including air)
WILLIAM Reply
using the law of reflection explain how powder takes the shine off a person's nose. what is the name of the optical effect?
WILLIAM
is higher resolution of microscope using red or blue light?.explain
WILLIAM
can sound wave in air be polarized?
WILLIAM Reply
Unlike transverse waves such as electromagnetic waves, longitudinal waves such as sound waves cannot be polarized. ... Since sound waves vibrate along their direction of propagation, they cannot be polarized
Astronomy
A proton moves at 7.50×107m/s perpendicular to a magnetic field. The field causes the proton to travel in a circular path of radius 0.800 m. What is the field strength?
Celedonio Reply
derived dimenionsal formula
Ajak Reply
what is the difference between mass and weight
Isru Reply
assume that a boy was born when his father was eighteen years.if the boy is thirteen years old now, how is his father in
Isru
what is head-on collision
Javaid Reply
what is airflow
Godswill Reply
derivative of first differential equation
Haruna Reply
why static friction is greater than Kinetic friction
Ali Reply
draw magnetic field pattern for two wire carrying current in the same direction
Ven Reply
An American traveler in New Zealand carries a transformer to convert New Zealand’s standard 240 V to 120 V so that she can use some small appliances on her trip.
nkombo Reply
What is the ratio of turns in the primary and secondary coils of her transformer?
nkombo
what is energy
Yusuf
How electric lines and equipotential surface are mutually perpendicular?
Abid Reply
The potential difference between any two points on the surface is zero that implies È.Ŕ=0, Where R is the distance between two different points &E= Electric field intensity. From which we have cos þ =0, where þ is the angle between the directions of field and distance line, as E andR are zero. Thus
MAHADEV
sorry..E and R are non zero...
MAHADEV

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play




Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'College physics' conversation and receive update notifications?

Ask