Nuclear Criticality Safety: Introduction to Nuclear Criticality Physics

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What is the primary objective of Nuclear Criticality Safety?

To initiate nuclear chain reactions

To develop new nuclear reactors

To protect against the consequences of an inadvertent nuclear chain reaction (correct)

To generate nuclear energy for industrial use

What is the definition of nuclear energy?

The ability to do work

Force times distance

Energy produced by a nuclear reaction (correct)

The energy released in a nuclear fission reaction

What is the term for the ability of a nucleus to undergo a nuclear reaction?

Critical

Radioactive

Fissionable (correct)

Fissile

What is the meaning of the term 'criticality' in Nuclear Criticality Safety?

The point at which a nuclear reaction becomes uncontrolled Signup and view all the answers

What is the formula for work?

Force times distance Signup and view all the answers

What is the goal of the ANSI/ANS-8.1 standard for Nuclear Criticality Safety?

To prevent the consequences of an inadvertent nuclear chain reaction Signup and view all the answers

What is the unit of energy equivalent to the mass of one atomic mass unit?

931.50 MeV Signup and view all the answers

What is the difference between the masses of the neutron and the hydrogen atom?

0.782 MeV Signup and view all the answers

What is the half-life of a free neutron?

10.4 minutes Signup and view all the answers

What is the result of the fission process in a nucleus?

The nucleus splits into two or occasionally three fragments Signup and view all the answers

What is the macroscopic cross section of a sample of uranium metal consisting of only 235U and 238U?

Σ = N235 σ235 + N238 σ238 Signup and view all the answers

What is the mass of one atomic mass unit in grams?

1.6606 x 10 -24 g Signup and view all the answers

What is the primary form of energy carried by the fragments in a fission reaction?

Kinetic energy Signup and view all the answers

What is the approximate energy released in the fission reaction described in the equation?

184 MeV Signup and view all the answers

Why is the mass of a nucleus slightly less than the sum of the masses of its constituents?

Due to the mass defect or binding energy Signup and view all the answers

What is the purpose of the graph shown in Figure 1?

To illustrate the binding energy per nucleon against atomic number Signup and view all the answers

What is the term for the energy required to break up a nucleus into its separate parts?

Binding energy Signup and view all the answers

What is the approximate number of neutrons emitted per fission?

2.5 Signup and view all the answers

How many neutrons are liberated in the fission reaction described in the equation?

201 Signup and view all the answers

What is the dependence of the number of prompt neutrons per fission on the energy of the neutrons causing fission?

ν(E) = ν0 + a*E Signup and view all the answers

Which nuclide has a higher value of ν, 239Pu or 235U?

239Pu Signup and view all the answers

What is the average energy of a neutron from a fission reaction?

2 MeV Signup and view all the answers

What is the range of energies of neutrons emitted from fission?

100 keV to 20 MeV Signup and view all the answers

What is the name of the distribution that describes the energy distribution of neutrons from fission?

Maxwellian distribution Signup and view all the answers

What is the energy of motion described as?

Kinetic energy Signup and view all the answers

What is the unit of energy in nuclear physics mentioned in the text?

Electron volt Signup and view all the answers

What is the equivalent of 1 electron volt in joules?

1.602 X 10^-19 joules Signup and view all the answers

What is the energy release from the fission of a 235U or 239Pu nucleus?

200 MeV Signup and view all the answers

What happens to the potential energy when you jump down the stairs or out of a window?

It is converted to kinetic energy Signup and view all the answers

What would a 200 MeV 'hotfoot' change the potential energy of a 150-pound man?

Make him jump very high Signup and view all the answers