CRUDs in Power Plants
In nuclear engineering, “CRUD” is a technical term for corrosion and wear products (rust particles, etc.) in the coolant that become radioactive when exposed to radiation. The term is actually an acronym for Chalk River Unidentified Deposits, originally found on the cladding, or outer coating, of fuel rods in the Canadian reactor for which it was named. CRUD may be defined as deposited or suspended circulating corrosion products, principally metal oxides, formed by the reaction of water with piping materials. According to the ICRP, CRUD formed in the power plants is the major source of operator radiation exposure.
Besides these radiological aspects CRUDs can have a number of adverse effects on the plant and its components. These can include the following:
- Mechanical fouling of equipment.
- Increase in the pressure drop across the core
The power plant must be designed to minimize corrosion and deposition. This design includes efficient removal of corrosion products, the purification system, design and arrange equipment to mnimize crud deposition, and select coolant chemistry to reduce corrosion.