What is the purpose of pH maintenance in reactor cooling systems?

• A. To reduce the likelihood of stress-induced cracks
• B. To maximize corrosion
• C. To increase hydrogen production
• D. To neutralize radioactivity

Answer: (A)

The key idea is that keeping the reactor coolant chemistry at an appropriate alkaline pH reduces corrosion-driven damage, especially stress corrosion cracking. When the water is too acidic or otherwise out of the proper pH range, protective oxide films on metal surfaces break down and tensile stresses in the metal can work with the corrosive environment to initiate and propagate cracks. Maintaining pH in the right alkaline range helps the oxide films stay stable, lowers the corrosion current, and reduces hydrogen-related embrittlement that can drive cracking. All of this lowers the chances of cracks forming and growing in critical components, which is why pH maintenance is used to protect reactor cooling system integrity.

The other options don’t fit because increasing corrosion, maximizing hydrogen production, or neutralizing radioactivity would not enhance safety or integrity; in fact, they would introduce new risks or fail to address the cracking mechanism.