METHOD FOR REFUELING WATER-GRAPHITE REACTORS TO INSPECT THEIR PROCESS CHANNELS Russian patent published in 2002 - IPC

FIELD: servicing nuclear power plants. SUBSTANCE: method involves extraction of fuel assemblies from channels, their transport to cooling pond, inspection of empty channels, replacement of defective channels followed by recharging process channels with fuel assemblies. Fuel assemblies are extracted only from some channels whose quantity should not exceed 5.9% of their total number in reactor; each group of channels is inspected, fuel assemblies are extracted from second-group channels to be inspected and charged into channels of first group that have passed inspections; then fuel assemblies are extracted from third group of channels to be inspected and charged into channels of second group that have passes inspections, and so on; the last group of channels is charged with fuel assemblies taken from cooling pond. Certain limits are imposed onto fuel burnout in charging fuel assemblies into process channels, that is, only channels in which fuel assemblies were originally of same enrichment with energy production deviation not over 200 MW/day per fuel assembly and mean energy production in multiple cell of four adjacent channels is not over 100 MW/day per fuel assembly should be charged and fuel assemblies with higher enrichment of 2.4% and energy production lower than 200 MW/day per fuel assembly are charged in non-adjacent channels. EFFECT: reduced number of transport and processing operations, reduced outage time and fuel trouble probability, enhanced radiation safety for personnel. 3 dwg, 7 tbl