Lesson 1 - Unit 10 Overview

It was necessary at this point to find a new term to define this new property of matter manifested by the elements of uranium and thorium. I proposed the word radioactivity which has since become generally adopted; the radioactive elements have been called radio elements.

Marie Curie

In Unit 1, Lesson 4 we noted that there are two different versions of the Contaminant Transport Module that can be licensed and added to GoldSim: the CT (Contaminant Transport) Module and the RT (Radionuclide Transport) Module.  Your copy of GoldSim will have neither, one, or the other (but not both), depending on your license.

Up until this point in the Course we have discussed features that are common to both the CT Module and the RT Module. In this Unit and the next, however, we will discuss several features and topics that are specific to the RT Module, the most important being the following:

• The RT Module allows decay chains (collections of daughter products) to be simulated (one species can be specified to transform into one or more others via a first-order reaction).  In addition, to support modeling of radioactive decay chains, the RT Module also allows you to utilize an extensive built-in database of radionuclide decay data.  The CT Module, on the other hand, allows you to model a first-order reaction (i.e., a decay rate), but you cannot specify reaction (daughter) products.
• The RT Module provides a special element called a Source.  The Source element can be used to simulate the complex release mechanisms of contaminants from engineered systems.  This is particularly useful when simulating the behavior of proposed or existing waste disposal facilities, which have as part of their design engineered packages or containers in which the waste is placed prior to disposal. 

If you are not interested in these topics, you can skip this Unit, as well as Unit 11 (which discusses the second feature listed above, the Source element), and proceed to Unit 12.

In this Unit, we will discuss the following:

• One of the most noticeable differences between the CT Module and the RT Module is the Species element (which is much more complex in the RT Module). We begin this Unit by explaining those differences. After doing so, we discuss how the RT Module can be used to simulate daughter products (i.e., reaction products).
• To support modeling of radioactive decay chains, the RT Module allows you to utilize an extensive built-in database of radionuclide decay data. Use of this database is discussed in detail.
• When modeling radionuclides, you will almost always need to represent multiple isotopes for various chemical elements (e.g., uranium-235 and uranium-238). Care must be taken when entering input data for isotopes, and this will be discussed.
• For most simulations involving radionuclide transport, you will not just be interested in computing concentrations or masses in environmental media. You will also be interested in computing doses to receptors (e.g., various populations who might come into contact with the species). GoldSim provides a specialized element (the Receptor) to facilitate the computation of doses that we will discuss.  (The Receptor is also available in the CT Module, but is most commonly used in conjunction with radionuclide simulations.)

This Unit has a total of 10 Lessons (including this overview and a summary at the end), as well as several Exercises and Examples.