Calculate relative concentrations (χ/Q) for control room habitability assessments

A control room.

ARCON is a computer code used to calculate atmospheric relative concentrations (X/Q) in support of control room habitability assessments required by 10 CFR Part 50, Appendix A, General Design Criterion 19. It uses hourly meteorological data and the atmosphere’s influence (i.e., dilution and dispersion) in the vicinity of buildings to calculate the relative concentration at control room air intakes. These concentrations would be exceeded no more than five percent of the time and calculated for averaging periods ranging from one hour to 30 days in duration.

The model is based on a straight-line Gaussian model that assumes the release rate is constant for the entire period of the release. ARCON can account for both plume meander under low wind speed conditions and the plume dispersion due to building wakes.