•The cooling flow rate for the HFIR HB-1 beam tube has been slowly degrading over time
•The HB-1 beam flow has now crossed the previously established low-flow alarm limit of 15 gallon/min
•This required a new HB-1 flow safety calculation to support resetting the alarm to a new lower limit
•An axisymmetric conjugate heat transfer CFD simulation with k-e and k-w (SST) turbulence model was developed in StarCCM+ to independently review the primary COMSOL Multiphysics calculation prepared by the HFIR staff
•A new low-flow alarm set point of 11 gallon/min was approved as an outcome of this study
