[en] The effects on water properties of boric acid and the variation in boric acid concentration in the reactor vessel during a postulated loss-of-coolant accident (LOCA) transient were determined. The concentration variation during a LOCA resulted in small water property changes except for viscosity and parameters in which viscosity appears, such as, Reynolds number and Prandtl number. During a LOCA transient, the concentration change would not be great enough for plateout to occur. In order to quantify the effects of boric acid on reactor safety analyses, LOCA simulation codes should be assessed to determine their sensitivity to water property changes attributable to boric acid