Effects of oxidation states of fuel cladding surface on crud deposition in simulated primary water of PWRs

The purpose of this work is to understand the pre-oxidation effect of fuel cladding surface on crud deposition in simulated primary water of PWRs at 328 °C. Crud deposition tests were performed using ZIRLO™ (ZIRLO™ is a trademark of Westinghouse Electric Company LLC in the United States of America) claddings with three different oxidation states under sub-cooled nucleate boiling conditions. Boiling characteristics on the cladding surfaces were also simultaneously monitored using acoustic emission technique. The deposited amount on the pre-oxidized claddings was increased by up to 45%, compared with that on the as-received clean cladding. The number of boiling events also showed higher values on the pre-oxidized claddings. The effect of the pre-oxidized layers is discussed in the view point of the degree of sub-cooled nucleate boiling, zeta potential and wettability.