FUEL PERFORMANCE IMPROVEMENT PROGRAM Power-Ramp Testing and Postirradiation Examination of PCI- Resistant LWR Fuel Rod Designs

This report describes the power-ramp testing results from 10 fuel rods irradiated in the Halden Boiling Water Reactor (HBWR), Halden, Norway. Tne work is part of the Fuel Performance Improvement Program (FPIP), which is sponsored by the U.S. Department of Energy (DUE) and is conducted through the joint efforts of Consumers Power Company, Exxon Nuclear Company, lnc., and Pacific Northwest Laboratory. The objective of the FPlP is to identify and demonstrate fuel concepts with improved pellet-cladding interaction (PCl) behavior that will be capable of extended burnup. The postirradiation examination results obtained from one nonramped rod are also presented. The power-ramping behavior of three basic fuel rod types--rods with annular-pellet fuel, sphere-pac fuel, and dished-pellet (reference) fuel--are compared in terms of mechanisms known to promote PCl failures. The effects of graphite coating on the inside cladding surface and helium pressurization in rods witn annular fuel are also evaluated