Introduction to Nuclear Criticality Safety

REVIEW TOPICS PART I

This review covers the information you should have already been exposed to and hopefully remember. There are many opportunities to test your knowledge through the use of "Quiz Me" interactives. The answers appear whenever you click the Check Answer button. You will not be graded for this review, but you will receive 50 total points for completion of all five parts. This is essential foundational knowledge for this and following courses in the Nuclear Criticality Safety series.

ATOMIC AND NUCLEAR PHYSICS

Definitions

Let's begin with some definitions:

mass number      

=

A, the total number of nucleons (neutron and proton) in a nucleus.

atomic number

=

Z, the number of protons in a nucleus.

nuclide

=

 

Value: 1

 

isotopes

=

 

Value: 1

 

isomers

=

 

Value: 1

 

=

symbol for nucleus of element X with atomic number Z and atomic mass number A.

 

=

in an excited state

 

 Fundamental Particles

The following particles are important in nuclear engineering (Lamarsh & Baratta, pp. 6-7).

Electron - Electrons can have a negative or a positive charge (these are rare). The electron has a charge of 1.60219×10-19 coulombs and a rest mass of 9.10954×10-31 kg.

Protron - Protons have a positive charge and rest mass of 1.67265 ×10-27 kg.

Neutron - Neutrons are electrically neutral and have a mass of 1.67495 ×10-27 kg.

Photon - Sometimes particles in nature don't always behave like particles but behave like waves. The photon is one of them and is associated with electromagnetic waves.   Photons have both zero charge and rest mass and travels in vacuum at the speed of light (c=2.9979×108 m/sec).

Neutrino - The neutrinos, like the photons, have no electrical charge and zero rest mass

Particle Wavelengths

It was mentioned previously that particles have an associated wavelength.     The wavelength l for particles that have zero rest mass (e.g., photons) is calculated from the expression [Id., equation 2.21]

                     

 where . . .

 

Match the items.

The task is to match the lettered items with the correct numbered items. Appearing below is a list of lettered items. Following that is a list of numbered items. Each numbered item is followed by a drop-down. Select the letter in the drop down that best matches the numbered item with the lettered alternatives.

a. Planck's constant (4.136×10-15 eV-sec)

b.  kinetic energy of the particle (eV)

c. speed of light (2.9979×108 m/sec)

d. wavelength (m)

 

The wavelength l for particles that have nonzero rest mass (e.g., neutrons) is calculated from the expression (Id., equation 2.16)

where . . .

 

Match the items.

The task is to match the lettered items with the correct numbered items. Appearing below is a list of lettered items. Following that is a list of numbered items. Each numbered item is followed by a drop-down. Select the letter in the drop down that best matches the numbered item with the lettered alternatives.

a. wavelength (cm)

b. kinetic energy of the particle (eV)

c. rest mass of the particle

d. Planck's constant (4.136×10-15 eV-sec)

 

 

It should also be mentioned that the kinetic energy of a particle of nonzero rest mass can be calculated from the expression (Id., equation 2.9)

                                             

where . . .

 

while rest mass energy is calculated from the expression (Id., equation 2.4)

The total energy of photons (with a zero rest mass) is given by (Id., equation 2.13)

                     

where . . .

 

 


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