1

Chapter 9 Nuclear Radiation

9.7 Energy of the Nucleus

2

Energy of the Nucleus

a. Mass-to-Energy Conversion1. Mass can be converted to energy during

nuclear reactions. 2. E = mc2.

b. Binding Energy1. The mass of a nucleus is always less than the

sum of the masses of its constituent nucleons. 2. This mass defect was converted to the

“binding energy” that holds the nucleons together.

3

Application of Nuclear Chemistry

Such as the study of the chemical effects resulting from the absorption of radiation within living animals, plants, and other materials. The radiation chemistry controls much of radiation biology as radiation has an effect on living things at the molecular scale, to explain it another way the radiation alters the biochemicals within an organism, the alteration of the biomolecules then changes the chemistry which occurs within the organism, this change in biochemistry then can lead to a biological outcome. As a result nuclear chemistry greatly assists the understanding of medical treatments (such as cancer radiotherapy) and has enabled these treatments to improve.

4

Radiation therapy (or radiotherapy) is the medical use of ionizing radiation as part of cancer treatment to control malignant cells (not to be confused with radiology, the use of radiation in medical imaging and diagnosis). Radiotherapy may be used for curative or adjuvant cancer treatment. It is used as palliative treatment (where cure is not possible and the aim is for local disease control or symptomatic relief) or as therapeutic treatment (where the therapy has survival benefit but is not curative). Total body irradiation (TBI) is a radiotherapy technique used to prepare the body to receive a bone marrow transplant. Radiotherapy has a few applications in non-malignant conditions, such as the treatment of trigeminal neuralgia, severe thyroid eye disease, pterygium, prevention of keloid scar growth, and prevention of heterotopic ossification. The use of radiotherapy in non-malignant conditions is limited partly by worries about the risk of radiation-induced cancers.

Varian Clinac 2100C Linear Accelerator

5

iodine-131 radioactiveDye injected into aHuman body

Alternative energy sources using nuclear energy, such as nuclear power plants and reactors.

6

Energy of the Nucleus (cont)

c. Fission1. Following splitting (fission) of the uranium-

235 nucleus, the masses of the products are less than the masses of the reactants.

2. The “missing mass” is released as energy.d. The Manhattan Project

1. The Manhattan Project was the code name for the effort to develop a fission-based atomic bomb during World War II.

7

A neutron bombardinga heavy nucleus begins fission

Fission event is within an atom bomb isinitiated by a neutron (gray) bombardinga heavy nucleus such as uranium.

The nucleus breaksInto smaller pieces, releasing a lot of energy

8

4 Major Research Teams involved in the Manhattan Project

The existing Metallurgical Laboratory at the University of Chicago, charged with the creation of a sustained nuclear fission chain reaction.A new laboratory near Knoxville, Tennessee (now known as the Oak Ridge National Laboratory), charged with the enrichment of U-235A new laboratory in Hanford, Washington, charged with the production, isolation and purification of Pu-239A new laboratory in Los Alamos, New Mexico, directed by J. Robert Oppenheimer, charged with the design and construction of the atomic bomb.

9

The now-familiar mushroom cloud of the Trinity test

Credit: Corbis

“Little Boy” dropped on Hiroshima, Japan

August 6th, 1945

“Fat Man” dropped on Nagasaki, Japan

August 9th, 1945

Hiroshima before (top) and after (bottom)Nagasaki before (top) and after (bottom)