What term describes the transport, deposition, and activation of corrosion products within the reactor coolant system that can circulate to core components and piping?

• A. Intergranular corrosion
• B. CRUD burst
• C. Radiolysis
• D. CRUD cycle

Answer: (D)

The concept here is how corrosion products behave inside the reactor coolant system: they form on metal surfaces, are carried by the coolant, deposit on core components, and can be activated by neutron flux so they circulate back into the system. This ongoing transport, deposition, and activation is captured by the CRUD cycle. CRUD stands for corrosion products, and the cycle describes their movement through the system, their buildup on fuel and other surfaces, and their subsequent irradiation to become radioactive.

Other terms refer to different phenomena. Intergranular corrosion is corrosion at grain boundaries in metal, not the transport and activation of corrosion products. Radiolysis is the breaking apart of water molecules under radiation, not the movement of corrosion products. CRUD burst describes a sudden release or surge of CRUD deposits, a transient event rather than the continuous cycle.