NUCE 304 Nuclear Non-proliferation Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the term used to describe the sum of all cross sections in nuclear interactions?

Total interaction cross section

Total scattering cross section

Total cross section (correct)

Total absorption cross section

Which cross section represents elastic scattering in nuclear interactions?

σe (correct)

σf

σi

σγ

What does the absorption cross section (σa) consist of?

Only fission cross sections

Only scattering cross sections

All absorption reaction cross sections (correct)

Fission and radiative capture cross sections

What factors affect the microscopic cross section?

The target nuclide and incident particle Signup and view all the answers

For which neutron velocity are cross sections commonly measured?

2200 meters/second Signup and view all the answers

In the context of microscopic cross sections, which term refers specifically to (n, 2n) reactions?

σ2n Signup and view all the answers

Which of the following is NOT a characteristic microscopic cross section?

σv Signup and view all the answers

What is typically assumed about the target nuclide when determining the microscopic cross section?

It is at rest Signup and view all the answers

What does the collision density (F) represent?

The number of interactions per unit volume per unit time. Signup and view all the answers

Which of the following best describes the units of macroscopic cross-section (Σ)?

cm⁻¹ Signup and view all the answers

Which factors affect the value of the macroscopic cross-section (Σ)?

Target atom density, interaction type, and projectile energy. Signup and view all the answers

What is the macroscopic total cross-section (Σt)?

N multiplied by the microscopic total cross-section. Signup and view all the answers

Given the fractional abundance of 235U as 0.0072 and its atomic weight as 238.0289, which statement is true?

The density of 235U can be calculated using its atomic weight and fractional abundance. Signup and view all the answers

What occurs during inelastic scattering involving neutrons?

A compound nucleus is formed and emits a lower energy neutron. Signup and view all the answers

What is the primary result of radiative capture of a neutron?

A gamma ray is emitted immediately after neutron absorption. Signup and view all the answers

In charged-particle reactions involving neutrons, which particle is typically ejected?

A charged particle such as a proton or alpha particle. Signup and view all the answers

What is the initial condition for neutron-producing reactions?

They require energetic neutrons to occur. Signup and view all the answers

Which of the following best describes what happens to kinetic energy in inelastic scattering?

Kinetic energy is lost and conservation of total energy is maintained. Signup and view all the answers

Which reaction type is significant in reactors containing heavy water or beryllium?

(n,2n) reactions involving energetic neutrons. Signup and view all the answers

How does a compound nucleus achieve its ground state after neutron scattering?

By emitting one or more gamma rays. Signup and view all the answers

What characterizes the 'neutron poison' mentioned in radiative capture?

It enhances the absorption of neutrons. Signup and view all the answers

What is the definition of mean free path (λ) in nuclear physics?

The average distance a neutron travels without an interaction. Signup and view all the answers

Given the equation λ = 1/Σt, what will happen to the mean free path if Σt increases?

The mean free path will decrease. Signup and view all the answers

What value would be used for Σt for thermal neutrons in a research reactor if it is given as 10 cm-1?

0.1 cm Signup and view all the answers

What does N refer to in the equation for macroscopic absorption cross-section for 235U?

The number of atoms per unit volume. Signup and view all the answers

If the macroscopic absorption cross-section for 235U is given as Σa(235U) = N • f • σa(235U), what does σa(235U) represent?

The probability per unit length of interaction. Signup and view all the answers

What is the primary role of elastic scattering in nuclear reactors?

To slow down neutrons effectively Signup and view all the answers

Which type of neutron interactions results in the target nucleus remaining in its ground state?

Elastic scattering Signup and view all the answers

Which neutron interaction type is primarily responsible for the generation of fission products?

Absorption Signup and view all the answers

What is the significance of neutrons having zero net electrical charge?

They can pass through electron clouds easily. Signup and view all the answers

Which process is considered the most important for slowing down neutrons in nuclear reactors?

Elastic scattering Signup and view all the answers

What occurs during inelastic scattering of neutrons?

Energy is transferred to excite the target nucleus. Signup and view all the answers

What do neutron-producing reactions involve?

Producing additional neutrons from interactions Signup and view all the answers

Why are fission products considered a major issue for nuclear power?

They can lead to safety and environmental concerns. Signup and view all the answers

What does the total collision density in the neutron beam experiment represent?

The total density of neutrons striking the target Signup and view all the answers

Which formula accurately represents neutron flux?

f = nv Signup and view all the answers

What is a correct unit for measuring neutron flux?

neutrons/cm2-s Signup and view all the answers

In the context of neutron beams, what does the symbol 'n' represent?

The total density of neutrons Signup and view all the answers

Which statement best describes neutron flux?

The rate at which neutrons pass through a unit area Signup and view all the answers

When considering neutron beams in a reactor, what can Ftotal be expressed as?

Ftotal = Σt (nv) Signup and view all the answers

Which of the following concepts are related to neutron flux?

Overall population of neutrons in a volume Signup and view all the answers

What does the symbol Σt represent in the equations discussed?

The summation of different neutron beam intensities Signup and view all the answers

Study Notes

NUCE 304: Evaluative Methods for Nuclear Non-proliferation and Security

Course is about evaluative methods for nuclear non-proliferation and security, focusing on neutron interactions.
Instructor is Dr. Ahmed Alkaabi.
Course code is NUCE 304.

Learning Objectives

Students will learn how nuclear power produces electrical power.
Students will understand how and why nuclear power works.
Students will be able to explain why fission products and radiation are significant concerns in nuclear power.
Students will grasp the role of neutron interactions in nuclear power systems.
Students will learn about different ways neutrons interact with matter.
Students will understand how these interactions enable nuclear reactors to function.
Students will understand how neutron interactions impact nuclear power.

Primary Learning Objectives

Identify various neutron interactions with matter.
Understand neutron interactions in the context of nuclear reactor control.

Lecture Outline

Neutron Interactions
- Scattering
- Absorption
- Fission
Cross Sections and Neutron Interaction Rates.

Neutron Interactions

Neutrons have no electrical charge.
They interact with atomic nuclei.
Types of Interactions
- Scattering
  - Elastic Scattering: The most significant process in slowing neutrons in reactors. Kinetic energy is transferred, and the target nucleus remains in its ground state – no energy transfer to excitation. Total kinetic energy is conserved -Inelastic Scattering: Target nucleus absorbs the incident neutron, forming a compound nucleus. Compound nucleus emits neutron at lower kinetic energy; the target nucleus becomes excited. Finally, the target nucleus falls back to the ground state by emitting one or more gamma rays. Total energy is conserved, but kinetic energy is not.
- Absorption
  - Radiative Capture: The target nucleus absorbs the neutron and forms a compound nucleus that immediately emits a gamma ray.
  - Charged-Particle Reactions: The target absorbs the neutron, forms a compound nucleus, and ejects a charged particle from the nucleus (e.g., proton, alpha). -Neutron-Producing Reactions: Energetic neutrons result in these reactions, which are important in reactors using heavy water or beryllium (e.g., Be-9 undergoing (n, 2n) to become Be-8).
- Fission: An atomic nucleus splits, releasing energy in radiation and energetic fission products.

Elastic Scattering (n, n')

Neutron strikes a nucleus.
The target nucleus is almost always in its ground state.
Some kinetic energy is transferred from neutron to the target nucleus.
The initial and final neutrons are not necessarily the same.
Target nucleus remains in its ground state.
Total kinetic energy is conserved.

Inelastic Scattering (n, n')

Target nucleus absorbes the incident neutron.
Compound nucleus is formed.
Compound nucleus emits a neutron with lower kinetic energy; target nucleus is left in an excited state.
Target nucleus reaches ground state by emitting one or more gamma rays.
Total energy is conserved, but kinetic energy is not.

Radiative Capture (n, γ)

The target nucleus absorbs the incident neutron.
A compound nucleus is formed.
The compound nucleus immediately emits a gamma ray.

Charged-Particle Reactions (n,a), (n, p), (n, d), (n, t)

Target nucleus absorbs the incident neutron.
A compound nucleus is formed.
Compound nucleus has relatively high excitation energy and ejects a charged particle (e.g., proton, alpha).

Neutron-Producing Reactions (n,2n), (n,3n), (n,xn)

These reactions occur with energetic neutrons.
Reactions important in reactors with heavy water or beryllium.

Nuclear Fission

A process where an atomic nucleus splits, releasing significant energy in radiation and fission products.
Typical nuclear fission reaction: 1n + 235U → 92U* → 140Cs + 93Rb + 3 1n (Note the asterisk indicates a highly-excited state).

Nomenclature

Spontaneous Fission: A nucleus spontaneously decays by fission.
Neutron-Induced Fission: Fission induced by neutron absorption by a nucleus.
Thermal Fission: Fission induced by thermal neutrons.
Fast Fission: Fission induced by fast neutrons (around 1 MeV energy).

Neutron Interactions: Further Insights

To safely and effectively operate a nuclear reactor, we need to predict and control the neutron population over time and space.
Neutron populations change due to scattering, absorption, fission, and capture.
The ability to calculate neutron behavior depends on understanding fraction of different interactions.
Need to know the rate of each interaction type.

Types of Neutron Interactions

Scattering
- Elastic scattering (n, n)
- Inelastic scattering (n, n')
Absorption
- Radiative capture (n,γ)
- Charged particle reactions (n,α), (n, p), (n, d), (n, t)
- Neutron producing reaction (n,2n), (n,3n), (n,xn)
Fission

Microscopic Cross Section Symbols

Microscopic cross section (σ): Probability of a neutron-target nucleus interaction.
Units are barns (1 barn = 10⁻²⁴ cm²).
Each interaction type has a specific microscopic cross section (σe, σi, σγ, σf, σa, etc.).

Microscopic Cross Section Symbols (Continued)

Total cross section (σt): Sum of all cross sections.
Absorption cross section (σα): Total absorption reaction cross sections.
Scattering cross section (σs): Sum of all scattering reaction cross sections.

Microscopic Cross Sections Dependencies

Microscopic cross section depends on the target nuclide, incident particle, relative speed of the target and particle, and incident particles' energy.
Typically, target nuclide is assumed at rest.

Where to get cross-section data

Online resources readily available (e.g., Chart of the Nuclides, various databases).
Standard reference values are available at 2200 m/s neutron velocity.

Elastic Scattering Cross Section Versus Energy of Incident Neutron

Graph showing elastic scattering cross section variations with energy.
Potential scattering region and resonance region are illustrated.

235U Fission and Radiative Capture Cross Sections

Graph showing the cross sections for nuclear fission and radiative capture in 235U versus energy.

238U Fission and Radiative Capture Cross Sections

Graph showing the cross sections for nuclear fission and radiative capture in 238U versus energy.

Cross Sections Versus Temperature

Cross sections can vary with material temperature.
Temperature affects the relative motion of particles within the materiel.
Resonance broadening occurs at higher temperatures, and this phenomenon is termed Doppler broadening.

Collision Density

Number of interactions per unit time and volume. F = σN I

Macroscopic Cross-section

Macroscopic cross-section (Σ) is the probability of interaction per unit length of neutron travel.
Σ = Nσ (where N is the number of nuclei per unit volume and σ is the microscopic cross-section).
The macroscopic cross section depends on atomic density and microscopic cross section.

Mean Free Path

The average distance a neutron travels before interacting.
λ=1/Σ

Several Neutron beams bombard a Small Target

Total collision density is given by F_total = ∑(nᵢ vᵢ).
nᵢ is the neutron density in the ith beam, vᵢ is the neutron velocity, and Σᵢ is the total macroscopic cross section.

Neutron Flux

The quantity nv is termed neutron flux and given the symbol ∅.
Its units are neutrons/(cm²·s).
Neutron fluxes can be conceptually viewed as:
- Related to the overall population of neutrons in that volume.
- The number of neutron track lengths per unit volume per unit time.
- The number of neutrons passing through a unit area per unit time.
Collision density is F = Σ∅.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers evaluative methods for nuclear non-proliferation and security, focusing on neutron interactions vital for understanding nuclear power systems. Test your knowledge on how nuclear power produces energy, the significance of fission products, and the role of neutron interactions in reactor control.