Definition & Operational Usage of Source Term
What Is Source Term?
In hazmat and CBRN response, a source term is the quantitative description of a chemical or radiological release — including release rate, total mass, physical state (liquid, gas, vapor), temperature, and discharge geometry — used in plume modeling.
Why Source Term Matters on the Fireground
Plume dispersion models (ALOHA/CAMEO) require accurate source term inputs. Entering correct leak hole dimensions, tank pressure, and chemical mass allows computer models to predict toxic cloud downwind distances accurately.
Relevant NFPA Standards
- NFPA 470: Hazardous Materials/Weapons of Mass Destruction (WMD) Standard for Responders
- OSHA 29 CFR 1910.120: Hazardous Waste Operations and Emergency Response (HAZWOPER)
Field Procedures & Tactical Steps
- Identify released chemical UN number and container specifications.
- Estimate release parameters: hole diameter, liquid pool surface area, tank operating pressure.
- Input source term data into ALOHA or CAMEO modeling software.
- Factor in ambient weather conditions (wind speed, direction, temperature, humidity).
- Generate toxic vapor plume map and establish downwind protective action distances.
Common Context & Application
Used by Hazmat Technicians and Planning Section specialists during chemical spill modeling and evacuation distance calculations.
Frequently Asked Questions about Source Term
What parameters define a chemical source term?
Why is source term data critical for evacuation decisions?
Other Names for Source Term
Source Term may also appear in training materials, NFPA standards, or department SOPs as: release characteristics, contaminant profile.
Relevant Tools
Operational calculators related to Source Term: