What is the role of hydrogen water chemistry (HWC) in nuclear plants?

• A. To suppress radiolysis, control oxidation, and reduce corrosion and cracking in reactor coolant.
• B. To increase conductivity of water.
• C. To remove all dissolved gases.
• D. To raise the reactor power.

Answer: (B)

Hydrogen water chemistry is used to control the chemical state of the reactor coolant by suppressing radiolysis and maintaining a reducing environment. In the reactor, radiation splits water to form oxidants like oxygen and hydrogen peroxide that promote corrosion and can drive cracking of metals. Adding hydrogen shifts the redox balance and reduces the buildup of oxidizing species, lowering dissolved oxygen and reactive oxygen species. This reduces corrosion and stress corrosion cracking in the coolant system and helps protect materials over time. It’s not about increasing water conductivity—conductivity is tied to dissolved ions, not hydrogen gas—and it doesn’t aim to remove all dissolved gases or raise reactor power.