You can control the manner in which GoldSim discretizes outer barrier failures in two ways. Both of these options are located in the Contaminant Transport tab of the Options dialog (accessed via Model | Options…):
The two options in the “Source” section can be used to control the manner in which GoldSim discretizes outer barrier failure.
Barrier failure type: This is a list box with two options: "Predicted failure time" (the default), and "Random failure time".
If "Predicted failure time" is selected, package failures are discretized by computing the cumulative fraction failed based on the distribution, multiplying this fraction by the total number of packages, and truncating or rounding (see below) to the nearest integer number of packages. As a result, multiple realizations of the same failure distribution will be identical.
If "Random failure time" is selected, the failure time for each package is randomly sampled from the distribution. As a result, multiple realizations of the same failure distribution will be slightly different.
Note: The Random failure time
option can not be applied to user-defined distributions. These
distributions are always computed based on predicted failure times.
Round (vs truncate) the computed number of waste-package failures: This checkbox determines how package failure is discretized (and only applies if "Predicted failure time" is selected under Barrier failure type). It is best explained using an example. Suppose you had 10 packages that failed uniformly over 10 years. If this box was checked, the first package would fail at 0.5 years, and the last package would fail at 9.5 years. If this box was cleared, the first package would fail at 1 year, and the last package would fail at 10 years.