slide1
Download
Skip this Video
Download Presentation
Nuclear Physics at BAU nuclear.bau.jo/ This course nuclear.bau.jo/Reactors

Loading in 2 Seconds...

play fullscreen
1 / 38

Nuclear Physics at BAU nuclear.bau.jo/ This course nuclear.bau.jo/Reactors - PowerPoint PPT Presentation


  • 175 Views
  • Uploaded on

501503747 Nuclear Reactors. Nuclear Physics at BAU http://nuclear.bau.edu.jo/ This course http://nuclear.bau.edu.jo/Reactors Prerequisites Nuclear and Radiation Physics 742 http://nuclear.bau.edu.jo/nuclear-radiation Advanced Statistical Mechanics 761. General subjects to be covered.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Nuclear Physics at BAU nuclear.bau.jo/ This course nuclear.bau.jo/Reactors' - xaria


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

501503747

Nuclear Reactors

  • Nuclear Physics at BAU
  • http://nuclear.bau.edu.jo/
  • This course
  • http://nuclear.bau.edu.jo/Reactors
  • Prerequisites
  • Nuclear and Radiation Physics 742
  • http://nuclear.bau.edu.jo/nuclear-radiation
  • Advanced Statistical Mechanics 761

Nuclear Reactors, BAU, First Semester, 2007-2008

(Saed Dababneh).

slide2

General subjects to be covered

  • Review of relevant studied material in nuclear physics.
  •        Concepts in neutron physics.
  •       The relevant physics related to nuclear technology:
      • Fission chain reaction.
      •   Neutron diffusion and moderation.
      • Heat removal from nuclear reactors.
      • Isotope separation.
      •   …
  •      Components of nuclear reactors.
  •       Nuclear reactor fuels and fuel cycles.
  • •       Nuclear reactor theory.
  • •       Basic concepts of radiation protection and nuclear safety, shielding and waste disposal.
  • •       Issues and prospects of nuclear power today and in the future.

Nuclear Reactors, BAU, 1st Semester, 2007-2008

(Saed Dababneh).

slide3

Grading

Review Test 05%

Mid-term Exam 20%

Projects, quizzes and HWs 25%

Final Exam 50%

  • Homeworks are due after one week unless otherwise announced.
  • Remarks or questions marked in red without being announced as homeworks should be also seriously considered!
  • Some tasks can (or should) be sent by email:
  • [email protected]

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide4

Review Test

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide5

Projects

  • Consider nuclear fuel cycles with emphasis on front ends.
          • Work as a team. Divide and organize the job among you.
          • Try to explore local applicability.
          • Due date (for written version): December 5th.
          • Presentation: Will be scheduled later.
  • Other small projects will be announced in class.

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide6

Nuclear Reaction Energetics (revisited)

  • Conservation Laws
  • Charge, Baryon number, total energy, linear momentum, angular momentum, parity, (isospin??)…….

b

pb

gs

a

pa

X

+ve Q-value  exoergic reaction.

-ve Q-value  endoergic reaction.

pY

Y

Stationary X ??

+ve Q-value  reaction possible if Ta 0.

-ve Q-value  reaction not possible if Ta 0. (Is Ta > |Q| sufficient?).

Conservation of momentum ……

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide7

Nuclear Reaction Energetics (revisited)

HW 1

  • Conservation of momentum.
  • We usually do not detect Y.
  • Show that:
  • The threshold energy (for Ta): (the condition occurs for  = 0º).
  • +ve Q-value  reaction possible if Ta 0.
  • Coulomb barriers…….!!!
  • -ve Q-value  reaction possible if Ta> TTh.

double valued !?

solve for Q

Q < 0

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide8

Nuclear Reaction Energetics (revisited)

HW 1(continued)

  • The double valued situation occurs between TTh and the upper limit Ta\.
  • Double-valued in a forward cone.

Q < 0

Discuss the elasticand inelastic scatteringof neutronsusing these relations.

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide9

Nuclear Reaction Energetics (revisited)

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide10

Nuclear Reaction Energetics (revisited)

What about neutron induced reactions?

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide11

Nuclear Reaction Energetics (revisited)

What about neutron induced reactions?

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide12

Nuclear Reaction Energetics (revisited)

What about neutron induced reactions?

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide13

Nuclear Reaction Energetics (revisited)

  • If the reaction reaches excited states of Y

58Ni(,p)61Cu

even less ….

less proton energy

Highest proton energy

See Figures 11.4 in Krane

What about neutron induced reactions?

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide14

Neutron Interactions (revisited)

  • Chadwick’s discovery.
  • Neutrons interact with nuclei, not with atoms. (Exceptions).
  • Recall from Nuclear Physics 742:
    • Inelastic scattering (n,n\). Q = -E* Inelastic gammas. Threshold?
    • Elastic scattering (n,n). Q = ?? (Potential and CN). Neutron moderation?
    • Radiative capture (n,). Q = ?? Capture gammas.
    • (n,), (n,p). Q = ?? Absorption Reactions.
    • (n,2n), (n,3n) Q = ?? Energetic neutrons on heavy water can easily eject the loosely bound neutron.
    • Fission. (n,f).
  • HW 2 Examples of such exo- and endo-thermic reactions with Q calculations.

Non-elastic

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide15

Neutron Scattering (revisited)

  • Elastic or inelastic.
  • Analogous to diffraction.
  • Alternating maxima and minima.
  • First maximum at
  • Minimum not at zero (sharp edge of the nucleus??)
  • Clear for neutrons.
  • Protons? High energy, large angles. Why?
  • Inelastic  Excited states, energy, X-section and spin-parity.

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide16

Reaction Cross Section (revisited)

  • Probability.
  • Projectile a will more probably hit target X if area is larger.
  • Classically:  = (Ra + RX)2.
  • Classical  = ??? (in b)n+ 1H, n + 238U, 238U + 238U
  • Quantum mechanically:  =  2.
  • Coulomb and centrifugal barriers  energy dependence of .
  • What about neutrons?
  • Nature of force:
  • Strong: 15N(p,)12C  ~ 0.5 b at Ep = 2 MeV.
  • Electromagnetic: 3He(,)7Be  ~ 10-6 b at E = 2 MeV.
  • Weak: p(p,e+)D  ~ 10-20 b at Ep = 2 MeV.
  • Experimental challenges to measure low X-sections..

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide17

Reaction Cross Section (Simple terms)

A (Area of the beam!!)

|v|

X

Position of a neutron 1 s before arriving at target

Target with N atoms.cm-3 or NAX atoms.

Monoenergetic neutrons of speed v (cm.s-1) and density n (cm-3)

Volume = vA

containing nvA neutrons that hit the “whole” target in 1 s.

Beam Intensity InvA/A = nv (cm-2s-1)

Number of neutrons interacting with target per second

 I, A, X and N

= t I N A X

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide18

Reaction Cross Section (Simple terms)

  • Number of neutrons interacting with target per second
  • = t I N A X
  • Number of interactions with a single nucleus per second
  • = t I Interpretation and units of .
  • nvA= IA neutrons strike the target per second, of these
  • tI neutrons interact with any single nucleus. Thus,
  • measures the probability for a neutron to hit a nucleus.

Study examples in Lamarsh

Total cross section

Total number of nuclei in the target

Effective cross-sectional area of the nucleus.

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide19

Reaction Cross Section (Simple terms)

Number of neutrons interacting with target per second

= t I N A X

Number of interactions per cm3 per second (Collision Density)

Ft= t I N = I t

t= N t

Study examples in Lamarsh

Total cross section

Volume of the target

Macroscopic total cross section.

Probability per unit path length.

Attenuation not moderation !

Mean free path

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide20

Reaction Cross Section (Simple terms)

Homogeneous Mixture

Molecule xmyn Nx=mN, Ny=nN

given that events at x and y are independent.

Study examples in Lamarsh

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide21

Reaction Cross Section (revisited)

Look for b

Detector for particle “b”

d

Ia

“b” particles / s

,

cm2

“X“ target Nuclei / cm2

“a” particles / s

Typical nucleus (R=6 fm): geometrical R2  1 b.

Typical : <b to >106 b.

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide22

Reaction Cross Section (revisited)

Many different quantities are called

“cross section”.

Krane Table 11.1

Angular distribution

Units … !

“Differential” cross section

(,) or ( )

or “cross section” …!!

Doubly differential

t for all “b” particles.

Energy state in “Y”

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide24

n-TOF

CERN

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide26

Different Features (revisited)

1/v

Fast neutrons should be moderated.

235U thermal cross sections

fission  584 b.

scattering  9 b.

radiative capture  97 b.

Fission Barriers

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide27

Neutron Induced Reactions (revisited)

X(n,b)Y

b(Q+En)

n(En)

Probability to penetrate the potential barrier

Po(Ethermal) = 1

P>o(Ethermal) = 0

For thermal neutrons

Q >> En

b(Q)  constant

Non-resonant

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide28

Neutron Induced Reactions (revisited)

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide29

Statistical Factor (revisited)

HW 3

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide30

Resonance Reactions (revisited)

J

Ex

a + X  Y + b Q > 0

b + Y  X + a Q < 0

Excited

State

Entrance Channel

a + X

Exit

Channel

b + Y

Inverse Reaction

Compound Nucleus C*

Identical

particles

  • Nature of force(s).
  • Time-reversal invariance.

Statistical

Factor ()

QM

HW 4

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide31

Resonance Reactions (revisited)

Projectile

Projectile

Target

Target

Q-value

Q-value

Q + ER = Er

E = E + Q - Eex

Direct Capture

(all energies)

Resonant Capture

(selected energies with large X-section)

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide33

Resonance Reactions (revisited)

Damped Oscillator

Oscillator strength

Damping

factor

eigenfrequency

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide34

Resonance Reactions (revisited)

Breit-Wigner formula

  • All quantities in CM system
  • Only for isolated resonances.

Reaction

Elastic scattering

Usually a>> b.

HW 5When does R take its maximum value?

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide35

Resonance Reactions (revisited)

Exit

Channel

b + Y

Ja + JX + l = J

(-1)l(Ja) (JX) = (J)

(-1)l = (J) Natural parity.

J

Ex

Excited

State

Entrance Channel

a + X

Compound Nucleus C*

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide36

Resonance Reactions (revisited)

What is the “Resonance Strength” …?

What is its significance?

In what units is it measured?

Charged particle

radiative capture (a,)

(What about neutrons?)

Cross section

EC

a



Energy

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide37

Neutron Resonance Reactions (revisited)

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

slide38

Neutron Activation Analysis (revisited)

(Z,A) + n (Z, A+1)

-

 (-delayed -ray)

(Z+1, A+1)

http://ie.lbl.gov/naa !

Project 1

Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

ad