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Historical Overview

Radiation Basics

Reactor Basics

Electric Power Basics

Nuclear Waste Basics

Disposal of Nuclear Waste

Development of the Nuclear Power Industry

Nuclear Power Statistics

Historical Safety Record

Issues in Nuclear Power

Nuclear Power News

Legacy of the Cold War

Nuclear Weapon FAQ

Atmospheric Nuclear Testing

Nuclear Links

Glossary of Nuclear Terms

This material was written and developed by Carey Sublette who has graciously allowed me to link to it. It provides a very thorough background and explaination of nuclear weapon development and technology. The original FAQ is located at The High Energy Weapons Archive, a site developed and written by Mr. Sublette which I recommend very highly for information regarding current force strengths of all nuclear nations, as well as other information regarding nuclear weapons. Following the table are more detailed descriptions of the contents of each section of the FAQ to help you find what you are looking for. These descriptions are taken directly from the FAQ.

Nuclear weapons can be grouped into different classes based on the nuclear reactions that provide their destructive energy, and on the details of their design. The popular division of nuclear weapons into fission bombs and fusion bombs is not entirely satisfactory. The spectrum of weapon design is more complex than this simple classification implies. All nuclear weapons so far invented require fission to initiate the explosive release of energy. Weapons that incorporate fusion fuel can do so in various ways, with different intended effects. This section attempts to survey the basic types of bomb designs systematically. More detailed discussions of the physics and design principles of each type will be covered in more detail in later sections.

• 1.1 Terminology
• 1.2 U.S. Nuclear Test Names
• 1.3 Units of Measurement
• 1.4 Pure Fission Weapons
• 1.5 Combined Fission/Fusion Weapons
• 1.6 Cobalt Bombs

Discussions of physical principle, particularly nuclear physics, is unavoidable in most of the sections of this FAQ. In this section I set forth the basic principles behind all nuclear weapons, although some familiarity with physics is assumed. Section 4 deals with the design and engineering of nuclear weapons in more detail, and the physics discussions there can be considered a continuation of Section 2.

• 2.1 Fission Weapon Physics
• 2.1.1 The Nature Of The Fission Process
• 2.1.2 Criticality
• 2.1.3 Time Scale of the Fission Reaction
• 2.1.4 Basic Principles of Fission Weapon Design
• 2.2 Fusion Weapon Physics
• 2.2.1 Candidate Fusion Reactions
• 2.2.2 Basic Principles of Fusion Weapon Design

This section provides background in the fundamental physical phenomena that govern the design of nuclear weapons, especially thermonuclear weapons. This section does not address nuclear physics which are introduced in Section 2, and discussed further in Section 4. It addresses instead the behavior of matter at high densities and temperatures, and the laws controlling its flow.

Although the reader may be able to follow the discussions of physics and design in Section 4 without it, familiarity with the principles discussed here is essential for genuine insight into the design of nuclear weapons. Since the same principles tend to crop up repeatedly in different contexts, and it is inconvenient to explain basic physics while addressing engineering considerations, I provide an overview of the non-nuclear physical principles involved below. Section 2 provides a discussion of the nuclear reactions involved.

Readers with a grounding in physics will find much of this discussion too elementary to be of interest. Please skip anything you are already familiar with.

• 3.1 Thermodynamics and the Properties of Gases
• 3.2 Properties of Matter
• 3.3 Interaction of Radiation and Matter
• 3.4 Hydrodynamics
• 3.5 Radiation Hydrodynamics
• 3.6 Shock Waves in Non-Uniform Systems
• 3.7 Principles of Implosion
• 3.8 Instability

This section collects material in the open literature to provide a coherent survey of nuclear weapons technology. Everything in this section is in the public domain (not the same thing as being unclassified however), or is reasonable extrapolation or speculation based on public domain material. It was prepared without my ever having had access to any material on nuclear weapons not in the public domain. Much of the source material has been in the public domain for decades. Lest I be accused of providing instructions for building atomic bombs, I will point out that the discussion is general in nature and nowhere are detailed designs described. The actual construction of even a simple device requires specific dimensions, masses, and specifications of composition. I do not provide these, nor have I ever seen or attempted to prepare such a detailed design.

• 4.1 Elements of Fission Weapon Design
• 4.1.1 Dimensional and Temporal Scale Factors
• 4.1.2 Nuclear Properties of Fissile Materials
• 4.1.3 Distribution of Neutron Flux and Energy in the Core
• 4.1.4 History of a Fission Explosion
• 4.1.5 Fission Weapon Efficiency
• 4.1.5.1 Efficiency Equations
• 4.1.5.2 Effect of Tampers and Reflectors on Efficiency
• 4.1.5.3 Predetonation
• 4.1.6 Methods of Core Assembly
• 4.1.6.1 Gun Assembly
• 4.1.6.2 Implosion Assembly
• 4.1.6.3 Hybrid Assembly Techniques
• 4.1.7 Nuclear Design Principles
• 4.1.7.1 Fissionable Materials
• 4.1.7.2 Composite Cores
• 4.1.7.3 Tampers and Reflectors
• 4.1.8 Fission Initiation Techniques
• 4.1.9 Testing
• 4.2 Fission Weapon Designs
• 4.2.1 Low Technology Designs
• 4.2.2 High Efficiency Weapons
• 4.2.3 Low Yield Weapons
• 4.2.4 High Yield Weapons
• 4.2.5 Special Purpose Applications
• 4.2.6 Weapon Design and Clandestine Proliferation
• 4.3 Fission-Fusion Hybrid Weapons
• 4.3.1 Fusion Boosted Fission Weapons
• 4.3.2 Neutron Bombs ("Enhanced Radiation Weapons")
• 4.3.3 The Alarm Clock/Layer Cake Design
• 4.4 Elements of Thermonuclear Weapon Design
• 4.4.1 Development of Thermonuclear Weapon Concepts
• 4.4.2 Schematic of a Thermonuclear Device
• 4.4.3 Radiation Implosion
• 4.4.3.1 The Role of Radiation
• 4.4.3.2 Opacity of Materials in Thermonuclear Design
• 4.4.3.3 The Ablation Process
• 4.4.3.4 Principles of Compression
• 4.4.3.5 Ignition
• 4.4.3.6 Burn and Disassembly
• 4.4.4 Implosion Systems
• 4.4.5 Fusion Stage Nuclear Physics and Design
• 4.4.5.1 Fusionable Isotopes
• 4.4.5.2 Neutronic Reactions
• 4.4.5.3 Fusion Fuels
• 4.4.5.4 Fusion Tampers
• 4.5 Thermonuclear Weapon Designs
• 4.5.1 Principle Design Types
• 4.5.2 "Dirty" and "Clean" Weapons
• 4.5.3 Maximum Yield/Weight Ratio
• 4.5.4 Minimum Residual Radiation (MRR or "Clean") Designs
• 4.5.5 Radiological Weapon Designs
• 4.6 Weapon System Design
• 4.6.1 Weapon Safety
• 4.6.2 Variable Yield Designs
• 4.6.3 Other Modern Features
• 4.7 Speculative Weapon Designs
• 4.8 Simulation and Testing

Nuclear explosions produce both immediate and delayed destructive effects. Immediate effects (blast, thermal radiation, prompt ionizing radiation) are produced and cause significant destruction within seconds or minutes of a nuclear detonation. The delayed effects (radioactive fallout and other possible environmental effects) inflict damage over an extended period ranging from hours to centuries, and can cause adverse effects in locations very distant from the site of the detonation. These two classes of effects are treated in separate subsections.

The distribution of energy released in the first minute after detonation among the three damage causing effects is:

                      Low Yield (<100 kt)   High Yield (>1 Mt)
Thermal Radiation        35%                      45%
Blast Wave               60%                      50%
Ionizing Radiation        5%                       5%
(80% gamma, 20% neutrons)

The radioactive decay of fallout releases an additional 5-10% over time.

• 5.1 Overview of Immediate Effects
• 5.2 Overview of Delayed Effects
• 5.3 Physics of Nuclear Weapon Effects
• 5.4 Air Bursts and Surface Bursts
• 5.5 Electromagnetic Effects
• 5.6 Mechanisms of Damage and Injury

This section describes the basic facts and properties about the materials that are uniquely important to applications involving the large scale release of nuclear power.

• 6.1 Production of Isotopes
• 6.2 Fissionable Materials
• 6.3 Fusionable Materials
• 6.4 Other Materials

There are currently five nations considered to be "nuclear weapons nations", an internationally recognized status conferred by the Non-Proliferation Treaty. In order of acquisition of nuclear weapons these are: the United States of America, Soviet Union/Russia, United Kingdom, France, and China. In actual fact, several more nations have developed nuclear weapons but do not publicly admit to having deployed them (in particular India, Israel, and Pakistan). Oddly enough, despite the decision of India and Pakistan to openly conduct weapons tests and declare themselves nuclear weapon states, they still have not acknowledged the possession of an actual deployed arsenal. Because of this, and the incidental fact that no other nation yet recognizes India or Pakistan as a nuclear power, I am retaining them as "suspect states" for the time being. The three smaller Soviet successor states that inherited nuclear arsenals (Ukraine, Kazakhstan, and Belarus) have now relinquished all nuclear warheads which have been removed to Russia.

• 7.1 Nuclear Weapon Treaties
• 7.2 Declared States
• 7.2.1 United States
• 7.2.2 Russia
• 7.2.3 Britain
• 7.2.4 France
• 7.2.5 China
• 7.3 Suspected States
• 7.3.1 India
• 7.3.2 Iran
• 7.3.3 Israel
• 7.3.4 Libya
• 7.3.5 North Korea
• 7.3.6 Pakistan
• 7.4 States Formerly Possessing or Pursuing Nuclear Weapons
• 7.4.1 Argentina
• 7.4.2 Brazil
• 7.4.3 Iraq
• 7.4.4 South Africa
• 7.4.5 South Korea
• 7.4.6 Sweden
• 7.4.7 Switzerland
• 7.4.8 Taiwan
• 7.4.9 Algeria
• 7.4.10 Former Soviet States
• 7.4.10.1 Ukraine
• 7.4.10.2 Kazakhstan
• 7.4.10.3 Belarus
• 7.5 Other Nuclear Capable States
• 7.5.1 Australia
• 7.5.2 Canada
• 7.5.3 Germany
• 7.5.4 Japan
• 7.5.6 Netherlands

This section describes the first fission and fusion bombs that were developed and tested. The purpose is three-fold. First, these devices are of considerable historical and public interest, the "first" of anything garners special attention. Second, these devices serve as archetypal examples of basic designs, and more information is available about these devices than later ones. Third, the effort and technology that was required to develop these devices provide indications of how easily primitive nuclear weapons can be developed by others.

• 8.1 The First Atomic Bombs
• 8.1.1 The Design of Gadget, Fat Man, and "Joe 1" (RDS-1)
• 8.1.2 TRINITY - The Gadget Test
• 8.1.3 Little Boy
• 8.1.4 Fat Man
• 8.1.5 Availability of Additional Bombs
• 8.2 The First Hydrogen Bombs
• 8.2.1 Early Research on Fusion Weapons
• 8.2.2 Design and Testing of the First Fusion Weapons

A proper history of the Manhattan Project, and the development of the first atomic bombs, is beyond the scope of this FAQ. I have included here a chronological listing of events and milestones leading up to the use of atomic weapons against Japan. Brief explanatory notes are inserted to provide some context and interpretation. The interested reader is directed to several excellent books available (see bibliography), particularly the Pulitzer Prize winning book by Rhodes, and Critical Assembly: A Technical History of Los Alamos During the Oppenheimer Years 1943-1945, from whom the bulk of the material for this timeline was extracted.

The timeline is divided into several epochs which seem to me to be naturally separated by critical events. Each epoch begins with a short summary of the key themes that characterize it. Although this is a strict chronology which list events that are more or less datable, occasional paragraphs are interspersed summarizing the thrust of events.

• 10.1 Early History of Nuclear Weapon
• 10.2 The Discovery of Fission and Its Properties
• 10.3 Organizing to Investigate Atomic Weapons
• 10.4 Organizing to Develop Atomic Weapons
• 10.5 The Manhattan Project - The Work Begins in Earnest
• 10.6 Racing Against Victory - The Final Year
• 10.7 Chronology of Atomic Weapons in the Soviet Union