CRUD deposits on heat transfer surfaces can affect which aspects of reactor operation?

• A. Only heat transfer
• B. Only shielding
• C. Heat transfer and corrosion behavior
• D. Heat transfer, shielding, and corrosion behavior

Answer: (D)

CRUD deposits on heat transfer surfaces influence three interconnected aspects of reactor operation. They first degrade heat transfer by forming an insulating layer that adds thermal resistance, which reduces heat transfer efficiency and can raise surface temperatures or risk of local boiling issues. They also alter the radiation environment around the plant because these deposits contain corrosion products that become activated in the neutron flux, increasing dose rates and the shielding or containment needed around surfaces and components. Finally, they change the local chemistry and surface conditions, promoting corrosion processes such as under-deposit corrosion, pitting, or crevice corrosion due to altered chemistry and micro-environments under the deposit. Because of these combined effects, CRUD deposits impact heat transfer, shielding, and corrosion behavior, not just one or two of them.