Lecture 16: In reactor chemistry

This lecture describes the chemistry of actinides and fission products in reactors, primarily focusing on phases formed in nuclear fuel. The fission process is reviewed and fuel burnup discussed. Determining fission product and actinide concentration to assess burnup is introduced. The variation of fission product and actinide concentration with burnup and initial fuel composition is provided. Axial and radial distribution of activity, fission products, and actinides is discussed, highlighting the role of neutron flux and energies on the distribution. Conditions necessary for the formation of separate phases in UO₂ are shown for perovskite and metallic phases, emphasizing the role of oxygen in the process. The behavior of fission products can be grouped into 4 areas: volatile species, metallic precipitates, oxide precipitates, and solid solutions.

Quiz 4: Am and Cm chemistry, reactors, radiation interaction, detectors

Assigned:  13 July 2014

Due:  18 July 2014

Topics

Lecture 15:  Am and Curium Chemistry Chemistry

Light Water Reactor Fuel

Fast Reactor, Gas Cooled Reactor

Fuel design considerations

History of nuclear fuel reprocessing

TRIGA Reactors

Radiation interactions and dosimetry

Detectors

Use lecture notes, textbooks, Chart of the Nuclides, Table of the Isotopes, and web pages.   Show your work or reference.  If you use a spreadsheet please include what equations you used to solve the problem.

Lecture 15: Am and Cm chemistry

This lecture introduces the chemistry of americium and curium. Both elements are discussed due to their similar chemical behavior, particularly in separations. However, important differences in their chemistry are highlighted. For americium pentavalent and hexavalent species are achievable. For curium, its unique fluorescence properties are highlighted. The nuclear properties of americium and curium isotopes are provided. Isotope production focus on those formed from multiple neutron capture. These isotopes, ²⁴¹Am, ²⁴³Am, ²⁴⁴Cm and ²⁴⁸Cm, are used to explore americium and curium chemistry. The basic solution chemistry is described, along with implications for fuel cycle separations. Methods for the separation of americium and curium are provided, including solvent extractions, anion exchange, precipitation, and molten salt techniques. Synthesis and characterization of americium and curium metals, alloys, and compounds are provided, with emphasis placed on those compounds of importance to the nuclear fuel cycle. The non-aqueous and coordination chemistry of these elements are introduced. The limited available data offers an avenue for novel explorations and future research directions. 

Lecture 14: Plutonium Chemistry

This lecture provides basic information on the chemistry of plutonium in three parts. Discussion on the nuclear properties of ²³⁸Pu and ²³⁹Pu are included. Environmental concentrations of plutonium, including ²⁴⁴Pu and naturally produced ²³⁹Pu, are discussed. Large scale plutonium separations are presented, including the PUREX process. The use of volatility and ion exchange as plutonium separation techniques are also given. The synthesis and properties are metallic plutonium are described in detail. An review of metal preparation methods are provided, including the plutonium-gallium phase diagram. The physical properties of plutonium metal are given and discussed. The solution chemistry of plutonium is depicted though coordination and spectroscopy as a function of oxidation state. Examples are provided on the various nature of plutonium chemistry in the solution phase, as colloids, and solid phase. The non-aqueous chemistry of plutonium is described and related to electronic structure. 

Lecture 13: Neptunium Chemistry

Neptunium chemistry is covered in this lecture. Nuclear properties and synthesis of neptunium are described, with emphasis placed on the isotopes ^235-239Np. The synthesis and properties of neptunium metal, alloys, and intermetallic compounds are introduced. The lecture describes neptunium compound synthesis, with resulting thermodynamic and structural properties provided. Neptunium organometallic and coordination compounds are also presented. Information on neptunium solution speciation, redox, and spectroscopy is given, with trends based on oxidation state examined. A presentation of analytical methods useful in neptunium chemistry, including Mössbauer spectroscopy, concludes the lecture. Comparisons are made with uranium chemistry to provide trends in the actinides. 

Lecture 11: Uranium chemistry

This lecture is in two parts. Uranium chemistry is covered in this lecture with an emphasis on separations and synthesis for the nuclear fuel cycle. Uranium is introduced with an overview of its chemistry for the fuel cycle. The solution chemistry of uranium is explored, focusing on uranyl. The molecular orbital of uranium is described. Separation of uranium by solvent extraction and ion exchange is presented. The enrichment of uranium from the uranium hexafluoride species is discussed, including diffusion, centrifuge, and laser methods. Oxide species of uranium are presented. Due to its potential as a nuclear fuel, the synthesis and properties of uranium metal and alloys are described in detail. With three different phase, the uranium metal exhibits more complex electronic behavior than the metals of the lighter actinides, a trend that continues to plutonium metal. 

Lecture 10: Speciation

This lecture covers fundamentals of chemical kinetics thermodynamics, mainly as a review. Emphasis of the lectures is applied to information useful for speciation modeling. Equilibrium constants are discussed. The role of chemical activity is provided. Calculations and models for speciation are presented. Equilibrium modeling using EXCEL and the program CHESS are presented. Solubility calculations are provides, with examples for the uranium system. 

Lecture 9: Nuclear Reactions

The lecture on nuclear reactions is presented in two parts. Nuclear reaction notation is introduced. The role of energetics in nuclear reactions is discussed and evaluated, including Q value, reaction barriers, and threshold energy. Center of mass and laboratory frames are discussed. The different processes involved in the formation of isotopes is provided including photonuclear processes. Reaction energetics, mechanisms and types are described. Nuclear reaction cross sections are described, with a presentation on values and limits given. This includes role of angular momentum in cross section values. The stellar production of elements is presented in terms of nuclear reactions. These provide the basis for understanding the formation of isotopes in stars.

Quiz 2: Beta Decay, Gamma Decay, Fission, Nuclear Models

Quiz 2 is posted.  It was assigned 20 June 2014 and is due 27 June 2014.   There will be office hours for the quiz at 4:45 PM, Thursday 26 June, 4th floor HRC.  The quiz covers:

Lecture 5:  Beta Decay

Lecture 6:  Gamma Decay

Lecture 7:  Fission

Lecture 8:  Nuclear Models

Use lecture notes, textbooks, Chart of the Nuclides, Table of the Isotopes, and web pages.   Show your work or reference.  If you use a spreadsheet please include what equations you used to solve the problem.

Lecture 8: Nuclear Force and Nuclear Models

This lecture provides information on nuclear force and nuclear models. The strong force is introduced through isospin. A comparison of exchange particles is provided. The use of mirror nuclei to examine the strong force is presented. An overview of nuclear potentials is provided and used as a basis of the shell model. States of the shell model and their relationship to magic numbers are discussed. Use of the shell model is determine nuclide spin and parity is presented. From the shell model the unpaired nucleon is used to assess overall nuclear spin. Examples are provided for nuclei with one or two unpaired nucleons. Nordheim rules are used to evaluation spin and parity with odd-odd nuclei. The relationship between spin and parity with nuclear deformation is introduced with Nilsson diagrams. Additional information on Nilsson diagrams can be found in the Table of the Isotopes. An introduction of the Fermi model for energetic nuclei is given. 

Lecture 7: Fission

A general overview of nuclear fission is presented. The probability of fission is described based on developed models including the liquid drop model and shell corrections. Discussion on spontaneous fission and fissioning isomers is given. The transition nucleus and fission product distributions are discussed. The total kinetic energy, mass distribution, and charge distribution during fission are presented. Changes in fission product distribution with parent properties are introduced. Delayed neutrons from fission and their role in reactors are given. Proton induced fission is introduced.

Lecture 6: Gamma Decay

Gamma decay is described in this lecture. The energetics involved in gamma decay are provided. Decay types in gamma transitions are explained, inclusion those that do not occur by photon emission. Transition probabilities and internal conversions inherent to gamma decay are covered. Links to find transition probabilities are provided. Electronic and magnetic multiple transitions are discussed. Angular correlations in gamma decay are described. The use of gamma decay in Moessbauer spectroscopy is presented.

Research projects

Research projects were reviewed on Monday 16 June.  The projects are the basis of the final presentation.  

Lecture 5: Beta Decay

Beta decay is presented in this lecture. The neutrino hypothesis and its relationship with beta decay is discussed. A review of Q value calculations for beta decay is provided. The importance of spin and parity, and how it can be used to assess beta decay, is discussed. Modeling beta decay through the weak force is provided.. The impact of Coulomb interactions on positron and electron spectral shape is presented. The use of Kurie plots in understanding beta decay is introduced. Selection rules in beta decay and beta transitions are explained. Calculating logft and its relation to spin and parity are presented. Double beta decay is discussed. 

Quiz 1: Chart of the Nuclides, Nuclear Properties, Decay Kinetics, Alpha Decay

Quiz 1 is posted.  It was assigned on 13 June 2014 and is due 20 June 2014.  There will be a meeting to discuss the quiz at 1700 on 19 June 14 in the 1st floor conference in the HRC. 

This first celebration of learning covers:

Lecture 1:  Introduction, Chart of the Nuclides

Lecture 2:  Nuclear Properties

Lecture 3:  Decay Kinetics

Lecture 4:  Alpha Decay

Laboratories

The Radiochemistry Fuel Cycle Summer School has three graded laboratories. The students are divided into three teams. Each team will perform the laboratory and provide a single write up for each laboratory. The grade for each laboratory will be shared amongst the team members. The laboratories will be performed 11-13 June 2014.  

Lecture 4: Alpha Decay

This lecture discusses alpha decay in radionuclides.  Theories on alpha decay are presented. Systematics and energetics involved in alpha decay are presented.  The correlation between Q value and decay energy is described.  The Geiger Nuttall relationship is provided, described, and utilized in a model for alpha decay. Tunneling is also exploited to described alpha decay, coupling energy and half-life.  Gamow calculations are shown to reflect the Geiger Nuttall relationship. Hindered alpha decay is discussed. Hindered alpha decay is employed to described nuclear properties. Hinderance factors are described, along with how they are calculated and where they can be found. Proton and other charged particle emission are presented.

Lecture 3: Decay Kinetics

This lecture covers the fundamental equations that describe the decay of radionuclides; covered in two parts. Basic equations and their utility are presented. The implications on error from counting is provided. Equations for mixtures, equilibrium, and branching of radionuclides are covered. The use of a program to solve the Bateman equation is presented.  The program is ERC Nuclide. The use of cross sections in determining production rates are covered. Saturation in isotope production due to the decay of the daughter is described. Discussion of natural radiation and dating are given. Examples are provided using the equations under a host of conditions. These include examples for dating from 238U, 14C, and the Oklo reactor. 

Lecture 2: Nuclear Properties

A discussion on systematics of nuclear properties is presented. Mass, mass excess, and mass distribution within the nucleus is presented. The liquid drop model is described, with the nuclear parameters discussed. Trends related to magic numbers are introduced. Mass excess data are used to calculate energies in decays. Equations for determining nuclear radii are provided. Models that are used to describe the stability of nuclei are introduced. Nuclear shapes and structures are introduced. Spin, parity, and magnetic properties of the nucleus are discussed. 

Lecture 1: Introduction

The class outcomes, expectations, and grading are explained.  Resources for the course are provided, including the chart of the nuclides and links to the table of the isotopes, programs, and databases. The laboratory courses and reserach expectations are introdued. A history of radioelement discovery and radiation research is presented. The Chart of the Nuclides is discussed and used. Atomic properties, nuclear nomenclature, X-rays, types of decays and physical forces are introduced.