<< Chapter < Page Chapter >> Page >
238 U + n 239 U + γ .

Uranium-239 then β decays:

239 U 239 Np + β + v e ( t 1/2 = 23 min) .

Neptunium-239 also β decays:

239 Np 239 Pu + β + v e ( t 1/2 = 2 . 4 d ).

Plutonium-239 builds up in reactor fuel at a rate that depends on the probability of neutron capture by 238 U size 12{ {} rSup { size 8{"238"} } U} {} (all reactor fuel contains more 238 U size 12{ {} rSup { size 8{"238"} } U} {} than 235 U size 12{ {} rSup { size 8{"235"} } U} {} ). Reactors designed specifically to make plutonium are called breeder reactors    . They seem to be inherently more hazardous than conventional reactors, but it remains unknown whether their hazards can be made economically acceptable. The four reactors at Chernobyl, including the one that was destroyed, were built to breed plutonium and produce electricity. These reactors had a design that was significantly different from the pressurized water reactor illustrated above.

Plutonium-239 has advantages over 235 U size 12{ {} rSup { size 8{"235"} } U} {} as a reactor fuel — it produces more neutrons per fission on average, and it is easier for a thermal neutron to cause it to fission. It is also chemically different from uranium, so it is inherently easier to separate from uranium ore. This means 239 Pu size 12{ {} rSup { size 8{"239"} } ital "Pu"} {} has a particularly small critical mass, an advantage for nuclear weapons.

Phet explorations: nuclear fission

Start a chain reaction, or introduce non-radioactive isotopes to prevent one. Control energy production in a nuclear reactor!

Nuclear Fission

Test prep for ap courses

Which of the following statements about nuclear fission is true?

  1. No new elements can be produced in a fission reaction.
  2. Energy released in fission reactions is generally less than that from fusion reactions.
  3. In a fission reaction, two light nuclei are combined into a heavier one.
  4. Fission reactions can be explained on the basis of the conservation of mass-energy.

(d)

Got questions? Get instant answers now!

What is the energy obtained when 10 g of mass is converted to energy with an efficiency of 70%?

  1. 3.93 × 10 27 MeV
  2. 3.93 × 10 30 MeV
  3. 5.23 × 10 27 MeV
  4. 5.23 × 10 30 MeV
Got questions? Get instant answers now!

In a neutron-induced fission reaction of 239 Pu, which of the following is produced along with 96 Sr and four neutrons?

  1. 56 139 Ba
  2. 56 140 Ba
  3. 54 139 Xe
  4. 54 140 Xe

(b)

Got questions? Get instant answers now!

When 235 U is bombarded with one neutron, the following fission reaction occurs: 92 235 U + n 56 141 Ba + y 92 Kr + x n .

  1. Find the values for x and y.
  2. Assuming that the mass of 235 U is 235.04 u, the mass of 141 Ba is 140.91 u, the mass of 92 Kr is 91.93 u, and the mass of n is 1.01 u, a student calculates the energy released in the fission reaction as 2.689 × 10 −8 , but forgets to write the unit. Find the correct unit and convert the answer to MeV.
Got questions? Get instant answers now!

Section summary

  • Nuclear fission is a reaction in which a nucleus is split.
  • Fission releases energy when heavy nuclei are split into medium-mass nuclei.
  • Self-sustained fission is possible, because neutron-induced fission also produces neutrons that can induce other fissions, n + A X FF 1 + FF 2 + xn , where FF 1 size 12{"FF" rSub { size 8{1} } } {} and FF 2 size 12{"FF" rSub { size 8{2} } } {} are the two daughter nuclei, or fission fragments, and x is the number of neutrons produced.
  • A minimum mass, called the critical mass, should be present to achieve criticality.
  • More than a critical mass can produce supercriticality.
  • The production of new or different isotopes (especially 239 Pu ) by nuclear transformation is called breeding, and reactors designed for this purpose are called breeder reactors.

Questions & Answers

what is angular velocity
Obaapa Reply
Why does earth exert only a tiny downward pull?
Mya Reply
hello
Islam
Why is light bright?
Abraham Reply
what is radioactive element
Attah Reply
an 8.0 capacitor is connected by to the terminals of 60Hz whoes rms voltage is 150v. a.find the capacity reactance and rms to the circuit
Aisha Reply
thanks so much. i undersooth well
Valdes Reply
what is physics
Nwafor Reply
is the study of matter in relation to energy
Kintu
a submersible pump is dropped a borehole and hits the level of water at the bottom of the borehole 5 seconds later.determine the level of water in the borehole
Obrian Reply
what is power?
aron Reply
power P = Work done per second W/ t. It means the more power, the stronger machine
Sphere
e.g. heart Uses 2 W per beat.
Rohit
A spherica, concave shaving mirror has a radius of curvature of 32 cm .what is the magnification of a persons face. when it is 12cm to the left of the vertex of the mirror
Alona Reply
did you solve?
Shii
1.75cm
Ridwan
my name is Abu m.konnek I am a student of a electrical engineer and I want you to help me
Abu
the magnification k = f/(f-d) with focus f = R/2 =16 cm; d =12 cm k = 16/4 =4
Sphere
what do we call velocity
Kings
A weather vane is some sort of directional arrow parallel to the ground that may rotate freely in a horizontal plane. A typical weather vane has a large cross-sectional area perpendicular to the direction the arrow is pointing, like a “One Way” street sign. The purpose of the weather vane is to indicate the direction of the wind. As wind blows pa
Kavita Reply
hi
Godfred
what about the wind vane
Godfred
If a prism is fully imersed in water then the ray of light will normally dispersed or their is any difference?
Anurag Reply
the same behavior thru the prism out or in water bud abbot
Ju
If this will experimented with a hollow(vaccum) prism in water then what will be result ?
Anurag
What was the previous far point of a patient who had laser correction that reduced the power of her eye by 7.00 D, producing a normal distant vision power of 50.0 D for her?
Jaydie Reply
What is the far point of a person whose eyes have a relaxed power of 50.5 D?
Jaydie
What is the far point of a person whose eyes have a relaxed power of 50.5 D?
Jaydie
A young woman with normal distant vision has a 10.0% ability to accommodate (that is, increase) the power of her eyes. What is the closest object she can see clearly?
Jaydie
29/20 ? maybes
Ju
In what ways does physics affect the society both positively or negatively
Princewill Reply
how can I read physics...am finding it difficult to understand...pls help
rerry Reply
try to read several books on phy don't just rely one. some authors explain better than other.
Ju
And don't forget to check out YouTube videos on the subject. Videos offer a different visual way to learn easier.
Ju
hope that helps
Ju
Practice Key Terms 9

Get the best College physics for ap... course in your pocket!





Source:  OpenStax, College physics for ap® courses. OpenStax CNX. Nov 04, 2016 Download for free at https://legacy.cnx.org/content/col11844/1.14
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'College physics for ap® courses' conversation and receive update notifications?

Ask