PWR FUEL DEPOSIT ANALYSIS AT A BW PLANT WITH A 24 MONTH FUEL CYCLE

摘要

The paper presents the crud analysis of a twice-burned fuel deposit using the AREVA crud sampling method in a domestic B&W PWR. The patented AREVA sampling method allowed the separation of deposit flakes that retain all the characteristics of unperturbed crud deposition.The twice-burned fuel assembly sampled was positioned in its second cycle of irradiation immediately against a fresh fuel assembly where the thermal-hydraulic (T/H) calculations indicated it as the first burn fuel assembly exhibiting the highest boiling for the core.Radiochemistry data will be presented that suggest that intense boiling was present at the location of the sample collection, producing a crud accumulation during the second cycle of operation considerably larger then during the first cycle of operation.The unperturbed 3D analysis of the deposition will be presented, allowing an in depth understanding of the processes of deposition on PWR fuel in conditions of intense localized boiling.