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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?

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.)

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} {} ?

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?


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

0.56 g

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

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

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?

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.

(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"} {} ?

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.

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?

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} {}

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?

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

Questions & Answers

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
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Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
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what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
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how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, Physics for the modern world. OpenStax CNX. Sep 16, 2015 Download for free at http://legacy.cnx.org/content/col11865/1.3
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