Comparison of Analysis Results on Three Methods for Sampling Crud, a Radioactive Corrosion Product with Zinc-Injected Spent PWR Nuclear Fuel Rods

Abstract

A radioactive corrosion product, Chalk River unidentified deposit (crud) was sampled and analyzed using an electron probe micro-analyzer with zinc-injected spent nuclear fuel rods (HU Unit 1, actual burnup 49 655 MWd/tonne U). Hot-cell facilities, a space for handling highly radioactive materials, were used as a way to collect crud deposited in the fuel rod cladding tube at a specific location of the spent fuel rod. A soft collection method for collecting crud using rubbings or adhesive tape was used to collect a sample, and a sample was collected with hard collection using a steel knife from the cladding tube of the fuel rod. The spent fuel rods were used for two cycles burned after zinc was injected into the primary coolant, which is known to inhibit the generation of crud. To compare the analysis results of the soft and hard collection methods for sampling crud, the results of the crud collected using an ultrasonic wave system were analyzed. The crud used in this study used burned fuel rods for two cycles after zinc ions were injected into the primary coolant. Based on the results, the Ni/Fe ratio can be estimated to be about 1.18. The Ni/Fe ratio value of 1.18 derived from this study is not much different from the Ni/Fe ratio values derived from nuclear power plants operating around the world.

Keywords:

• Crud
• ultrasonic crud cleaner
• Ni/Fe ratio
• shielded electron probe micro-analyzer
• fuel rod scraper