Oxide particle size distribution from shearing irradiated and unirradiated LWR fuels in Zircaloy and stainless steel cladding: significance for risk assessment
Sieve fractionation was performed with oxide particles dislodged during shearing of unirradiated or irradiated fuel bundles or single rods of UO/sub 2/ or 96 to 97% ThO/sub 2/--3 to 4% UO/sub 2/. Analyses of these data by nonlinear least-squares techniques demonstrated that the particle size distribution is lognormal. Variables involved in the numerical analyses include lognormal median size, lognormal standard deviation, and shear cut length. Sieve-fractionation data are presented for unirradiated bundles of stainless-steel-clad or Zircaloy-2-clad UO/sub 2/ or ThO/sub 2/--UO/sub 2/ sheared into lengths from 0.5 to 2.0 in. Data are also presented for irradiated single rods (sheared into lengths of 0.25 to 2.0 in.) of Zircaloy-2-clad UO/sub 2/ from BWRs and of Zircaloy-4-clad UO/sub 2/ from PWRs. Median particle sizes of UO/sub 2/ from shearing irradiated stainless-steel-clad fuel ranged from 103 to 182 ..mu..m; particle sizes of ThO/sub 2/--UO/sub 2/, under these same conditions, ranged from 137 to 202 ..mu..m. Similarly, median particle sizes of UO/sub 2/ from shearing unirradiated Zircaloy-2-clad fuel ranged from 230 to 957 ..mu..m. Irradiation levels of fuels from reactors ranged from 9,000 to 28,000 MWd/MTU. In general, particle sizes from shearing these irradiated fuels are larger than those from the unirradiated fuels; however, unirradiated fuel from vendors was not available for performing comparative shearing experiments. In addition, variations in particle size parameters pertaining to samples of a single vendor varied as much as those between different vendors. The fraction of fuel dislodged from the cladding is nearly proportional to the reciprocal of the shear cut length, until the cut length attains some minimum value below which all fuel is dislodged. Particles of fuel are generally elongated with a long-to-short axis ratio usually less than 3. Using parameters of the lognormal distribution estimates can be made of fractions of dislodged fuel having dimensions less than specified values.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5955720
- Report Number(s):
- NUREG/CR-0866; ORNL/NUREG-60; TRN: 79-018278
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FUEL ELEMENT CLUSTERS
HEAD END PROCESSES
FUEL RODS
SPENT FUEL ELEMENTS
BWR TYPE REACTORS
CUTTING
DISTRIBUTION
PARTICLE SIZE
PWR TYPE REACTORS
STAINLESS STEELS
THORIUM OXIDES
URANIUM DIOXIDE
WATER COOLED REACTORS
ZIRCALOY 2
ACTINIDE COMPOUNDS
ALLOYS
CHALCOGENIDES
CHROMIUM ADDITIONS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
FUEL ASSEMBLIES
FUEL ELEMENTS
IRON ADDITIONS
IRON ALLOYS
IRON BASE ALLOYS
MACHINING
OXIDES
OXYGEN COMPOUNDS
REACTOR COMPONENTS
REACTORS
SIZE
STEELS
THORIUM COMPOUNDS
TIN ALLOYS
URANIUM COMPOUNDS
URANIUM OXIDES
WATER MODERATED REACTORS
ZIRCALOY
ZIRCONIUM ALLOYS
ZIRCONIUM BASE ALLOYS
050800* - Nuclear Fuels- Spent Fuels Reprocessing