Experimental Modeling of Hydrogen Evolution Rates from Surfaces with Exposed Zinc Metal or Zinc Primer Coating in Contact with Containment Sprays in PWR Nuclear Power Plants

The interiors of pressurized water reactor containments have some construction materials and equipment surfaces coated with zinc primer and galvanized zinc. In the event of a loss-of-coolant accident, the surfaces may be exposed to hot spray solutions. The spray solutions recommended by the nuclear industry contain boric acid buffered with either sodium hydroxide or trisodium phosphate. These solutions react with zinc to produce gaseous hydrogen and zinc compounds. Rates of hydrogen evolution from zinc surfaces immersed in (a) spray solution containing boric acid and sodium hydroxide (pH = 9.8), and (b) solution containing boric acid and trisodium phosphate (pH = 7.5) can be correlated within experimental error by the equations:a. log₁₀R = −1.5 × 10³ T⁻¹ + 0.4b. log₁₀R = −1.1 × 10³ T⁻¹ + 0.6.