The replacement and addition of laboratory fumehoods were among the modifications to the existing laboratory exhaust system. Burns & McDonnell designed and specified additional exhaust system air scrubbers. In a separate project, the firm designed modifications to the exhaust and make-up air systems to correct an imbalance in building pressurization. A new make-up air system utilized heat from a reactor core to provide supplemental (free) heat to preheat coils. An exhaust system upgrade increased exhaust capacity as well as added scrubbers and carbon filters to handle acid and radioactive exhausts.