Understanding Radiation


What is radiation, you ask? Radiation in physics is the process of emitting energy in the form of waves or particles. Various types of radiation may be distinguished, depending on the properties of the emitted energy/matter, the type of the emission source, properties and purposes of the emission, etc. When used by the general public, the word “radiation” commonly refers ... Read More »

Leaving the Bomb Shelter

Radiation Warning

When the exposure rates outside the bomb shelter are known, use the Permissible Activities Table (below) as a general guide for permissible activities. Table – General Guide for Permissible Activities Outside the bomb shelter If the outside exposure rate (R/hr) is: Permissible Activities: More than 100 Outdoor activity may result in sickness or death. Occasions which might call for outside ... Read More »

U.S. Unprepared for Dirty Bomb


Congressional report: Nation lacks labs to test for contamination after blast The Associated Press Updated: 5:56 p.m. ET Oct 25, 2007 WASHINGTON – The U.S. has a shortage of laboratories to test the thousands of people who might be exposed to radiation if a “dirty bomb” detonated in a major city, according to a congressional report released Thursday. If a ... Read More »

Understanding Radiation: Types of Nuclear Explosions

mushroom cloud

The immediate phenomena associated with a nuclear explosion, as well as the effects of shock and blast and of thermal and nuclear radiations, vary with the location of the point of burst in relation to the surface of the earth. For descriptive purposes five types of burst are distinguished, although many variations and intermediate situations can arise in practice. The ... Read More »

Understanding Radiation: Sources of Radiation

Mushroom Cloud Nuclear Explosion

Blast and thermal effects occur to some extent in all types of explosions, whether conventional or nuclear. The release of ionizing radiation, however, is a phenomenon unique to nuclear explosions and is an additional casualty producing mechanism superimposed on blast and thermal effects. This radiation is basically of two kinds, electromagnetic and particulate, and is emitted not only at the ... Read More »

Understanding Radiation: Scientific Basis of Nuclear Explosions – Thermal Radiation

radiation spectrum

The observed phenomena associated with a nuclear explosion and the effects on people and materials are largely determined by the thermal radiation and its interaction with the surroundings. It is desirable, therefore, to consider the nature of these radiations somewhat further. Thermal radiations belong in the broad category of what are known as “electromagnetic radiations.” These are a kind of ... Read More »

Understanding Radiation: Scientific Basis of Nuclear Explosions – Time Scale of a Fission Explosion

Mushroom Cloud Nuclear Explosion

An interesting insight into the rate at which the energy is released in a fission explosion can be obtained by treating the fission chain as a series of “generations.” Suppose that a certain number of neutrons are present initially and that these are captured by fissionable nuclei; then, in the fission process other neutrons are released. These neutrons, are, in ... Read More »

Understanding Radiation: Scientific Basis of Nuclear Explosions – Thermonuclear Fusion Reactions

nuclear fission

Energy production in the sun and stars is undoubtedly due to fusion reactions involving the nuclei of various light (low atomic weight) atoms. From experiments made in laboratories with charged-particle accelerators, it was concluded that the fusion of isotopes of hydrogen was possible. This element is known to exist in three isotopic forms, in which the nuclei have mass numbers ... Read More »

Understanding Radiation: Scientific Basis of Nuclear Explosions – Fission Products

fission products

Many different initial fission product nuclei, i.e., fission fragments, are formed when uranium or plutonium nuclei capture neutrons and suffer fission. There are 40 or so different ways in which the nuclei can split up when fission occurs; hence about 80 different fragments are produced. The nature and proportions of the fission fragment nuclei vary to some extent, depending on ... Read More »

Understanding Radiation: Scientific Basis of Nuclear Explosions – Fission Energy

uranium fission

The significant point about the fission of a uranium (or plutonium) nucleus by means of a neutron, in addition to the release of a large quantity of energy, is that the process is accompanied by the instantaneous emission of two or more neutrons; thus, __________________________________________________________ Table 6-1. Neutron + uranium-235 = fission fragments + (or uraniurn-233) 2 or 3 neutrons ... Read More »