Which corrosion type only impacts PWRs and is a concern for leak conditions as the primary system is stainless steel?

• A. Microbiologic corrosion
• B. Boric acid corrosion
• C. Pitting corrosion
• D. Crevice corrosion

Answer: (B)

In a PWR, the primary coolant is borated water, so boric acid can be present in the system. When leak conditions occur, boric acid concentrates in stagnant areas and crevices on stainless steel surfaces, weakening the protective oxide film and driving localized attack. This specific situation—boric acid–containing coolant concentrating at leaks—leads to a distinctive form of corrosion that is particularly associated with PWRs. Other forms mentioned can occur in many environments and aren’t tied to the borated-water, leak-driven context unique to PWR primary systems, so boric acid corrosion is the best fit for this scenario.