Defining a Receptor

Although you could compute impacts by simply using an Expression element A function element that produces a single output by calculating user-specified mathematical expressions., for convenience, the Contaminant Transport Module provides a specialized version of an Expression element called a Receptor A group (usually of people) that could potentially receive impacts from contaminants in the environment. In GoldSim, a Receptor is an element that converts contaminant concentrations in the environment to impacts to a receptor group. to facilitate this calculation.

The dialog for a Receptor is shown below:

The dialog has three inputs:

Impact type: This is the type of impact to be computed. GoldSim provides three options:

• Risk (e.g., health or cancer risk);
• Dose (radioactive dose); and
• Hazard Index.

The choice of the Impact type determines the dimensions An output attribute for an element that defines the dimensionality (in terms of Length, Time and other fundamental dimensions) of the output. of the Receptor output (and therefore the dimensions of the vector A one-dimensional array. accepted by the Impact input field):

• A Risk has dimensions of inverse time (e.g., the incremental cancer risk per individual per year);
• A Dose has dimensions of radiation dose per time (e.g., mrem/yr, Sv/yr);
• A Hazard Index is dimensionless and is intended to represent a ratio of concentrations (the concentration in a medium divided by some reference concentration).

Impact: This is the equation describing the impact itself. It must be a vector by species The chemical (or non-chemical, such as bacterial or viral) constituents that are stored and transported through an environmental system in a contaminant transport model. In GoldSim, the Species element defines all of the contaminant species being simulated (and their properties).. Its dimensions are determined by the impact type.

For Risk and Dose impacts, it will typically be specified as a sum of several term-by-term vector multiplications (a concentration vector multiplied by an impact conversion factor vector).

For a Hazard Index impact, it will typically be specified as a sum of several term-by-term vector divisions (a ratio of concentrations).

The multiplication (*) and division (/) operators can be used to carry out a term-by-term multiplication or division of two vectors.

Display Units: This is the units in which the output of the Receptor is displayed. The acceptable dimensions are determined by the Impact Type (inverse time for Risk, dose/time for Dose, dimensionless for Hazard Index).