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NEA-1841 IFPE/EXP-BDL-406.

IFPE/EXP-BDL-406, performance of natural UO2 fuel irradiated at low linear powers in NRU

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1. NAME OF EXPERIMENT:  IFPE/EXP-BDL-406.
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2. COMPUTERS
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Program name Package id Status Status date
IFPE/EXP-BDL-406 NEA-1841/01 Arrived 15-JUN-2009

Machines used:

Package ID Orig. computer Test computer
NEA-1841/01 Many Computers
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3. DESCRIPTION OF EXPERIMENT

Experiment EXP-BDL-406
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Bundles XY, AAH and GF were part of experiment EXP-BDL-406, which investigated the performance of natural UO2 fuel irradiated at low linear powers (30-40 kW/m) to burnups above 450 MWh/kgU in the NRU reactor. The bundles achieved chemically determined outer element burnups of 689 and 902 MWh/kgU and BURFEL-calculated burnups of 717 and 953 MWh/kgU (a description of the BURFEL code is found below). Bundles AAH, XY and GF were manufactured by GE Canada during the production run of Bruce NGS-A first-charge fuel, and contained outer-element gas plenums. Results of the PIE on AAH suggested that CANDU 37-element fuel can be irradiated to outer element burnups above 700 MWh/kgU for declining power histories, provided the maximum linear powers remain below 40 kW/m. The results of PIE on Bundle GF, the higher-burnup bundle, suggest that plenums may be beneficial to fuel performance and that parameters other than temperature can influence fuel performance at extended burnup.
  
Experimental Bundle XY
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Bundle XY was first installed on 1975 October 03, and last discharged from the reactor on 1988 May 16, with an accumulated outer-element burnup of 565 MWh/kgU (as calculated by the BURFEL code). Bundle XY experienced a relatively steady irradiation with a sustained maximum outer-element linear power (OELP) of 33 kW/m.

Experimental Bundle AAH
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Bundle AAH was manufactured in 1975/76. The bundle was of the Bruce NGS-A "first-charge" design that contained gas plenums in the outer elements.
  
The primary objective of the PIE was to observe the performance of CANDU fuel at extended burnups (>450 MWh/kgU), which was of interest to reactor operators who desire a better understanding of the limits of operation, particularly for fuel resident in fuel channels that cannot be refuelled for an extended period of time, and for fuel designers who desire a better understanding of parameters that influenced performance.
  
Bundle AAH was first installed in NRU on 1977 January 18, and was last discharged from the reactor on 1990 February 16, with an accumulated outer-element burnup of 717 MWh/kgU, as calculated by BURFEL. Being a filler bundle, bundle AAH was removed and installed in the reactor numerous times during the irradiation history. Bundle AAH experienced a declining power history with a sustained maximum outer element linear power of 37 kW/m. Burnup and linear power were calculated by BURFEL. It should be noted that most of the irradiation was conducted in the presence of a significant axial power gradient, which generally produced end-to-end variations of up to 20% in power and burnup.
  
The post-irradiation examination of the bundle included bundle visual examination, element bow measurements of selected elements, measurement of element mid-pellet diameter at selected distances from the reference ends, pellet-interface ridge height, element gas-puncture analysis, burnup analysis on selected outer and intermediate elements, and ceramographic and metallographic examination to determine UO2 grain size, CANLUB retention, sheath oxide thickness and hydride distribution.
  
Experimental Bundle GF
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Natural UO2 bundle GF was manufactured by GE Canada in 1975.  Bundle GF (Exp-BDL-406) was successfully irradiated in the NRU reactor between 1975 and 1990 to an outer-element burnup of about 900 MWh/kgU at linear powers of about 30 kW/m.  The bundle was of the Bruce NGS-A "first-charge" design that contained gas plenums in the outer elements.
  
The primary objective of the PIE was to observe the performance of CANDU fuel at extended burnups (>450 MWh/kgU), which was of interest to reactor operators who desire a better understanding of the limits of operation, particularly for fuel resident in fuel channels that cannot be refuelled for an extended period of time, and for fuel designers who desire a better understanding of parameters that influenced performance.
  
Bundle GF was first installed in NRU on 1975 July 31 and was last discharged from the reactor on 1989 August 13, with an accumulated outer-element burnup of 953 MWh/kgU, as calculated by BURFEL. Being a filler bundle, bundle GF was removed and installed in the light-water-cooled loops in the reactor numerous times during its irradiation history. Bundle GF experienced a relatively high power (41 kW/m for sustained maximum) in the very early stage of the irradiation (< 5 MWh/kgU) and was then maintained at a relatively steady power (around 30 kW/m) for the rest of its irradiation.  For the purpose of comparing the performance of bundle GF with that of other extended-burnup bundles, the power history of bundle GF is classified as "constant".  Burnups and linear powers were calculated by BURFEL.  Bundle GF was irradiated primarily in axial position 3 and 4 where the flux profile is relatively flat (maximum +10% power variation relative to element midplane).  The effect of moving bundle GF from position 3 to 4 would be to flatten the burnup profile; BURFEL-calculated burnups at outer element upper and lower locations at discharge were only 0.0 and -1.2% from the burnup at midplane.
  
The post-irradiation examination of bundle GF included bundle visual examination, measurement of element mid-pellet diameter at selected distances from the reference ends, pellet-interface ridge height, element gas-puncture analysis, burnup analysis on selected outer and intermediate elements, sheath hydrogen analysis of selected outer, intermediate and inner elements and ceramographic and metallographic examination to determine UO2 grain size, CANLUB retention, sheath oxide thickness and hydride distribution.
  
Note on the BURFEL Code
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BURFEL (BURnup of Fuel Elements) is an AECL computer code that is used for the prediction of fuel powers in the NRU (National Research Universal) Reactor experimental loops, and for the analysis of fuel bundle and fuel pin powers after an actual irradiation using calorimetric data from the loops.  More detailed information on BURFEL may be found in the following paper:
  
M.D. Atfield, "Calculation of Power Distributions for Experimental Bundles in the NRU Loops", 22nd Annual CNS Conference, Toronto, Ontario, June 11 - June 13, 2001, published by the Canadian Nuclear Society, ISBN 0-919784-69-0.
This paper is available by request from the Chalk River Laboratories Library (librarycr@aecl.ca)
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9. STATUS
Package ID Status date Status
NEA-1841/01 15-JUN-2009 Arrived at NEADB
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10. REFERENCES

- M.D. Atfield:
"Calculation of Power Distributions for Experimental Bundles in the NRU Loops", 22nd Annual CNS Conference, Toronto, Ontario, June 11 - June 13, 2001, published by the Canadian Nuclear Society, ISBN 0-919784-69-0*
*This paper is available by request from the Chalk River Laboratories Library (librarycr@aecl.ca)
NEA-1841/01, included references:
- Bundles XY, AAH and GF (AECL, Chalk River Laboratories)
- Y.N. Zhou, M.R. Floyd, M.A. Ryz:
"Performance of Bruce Natural UO2 Fuel Irradiated to Extended Burnups",
AECL-11454, 1995 November.
- M. R. Floyd, J. Novak and P. T. Truant:
"Fission-Gas Release in Fuel Performing to Extended Burnups in Ontario Hydro
Nuclear Generating Stations", AECL-10636, 1992 June.
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12. PROGRAMMING LANGUAGE(S) USED

No item found

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15. NAME AND ESTABLISHMENT OF AUTHORS

Atomic Energy of Canada Ltd.
Chalk River Laboratories
Chalk River, ON K0J 1J0
Canada
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16. MATERIAL AVAILABLE
NEA-1841/01
Table 1: Fabrication Parameters for Bundles XY, AAH and GF
Table 2: BURFEL- Calculated NRU Loop Operatiion Data at Element Midplane
Table 3a: Normalized Outer Element Burnup for Bundle XY
Table 3b: Normalized Outer Element Burnup for Bundle AAH
Table 3c: Normalized Outer Element Burnup for Bundle GF
Table 4a: Average Normalized Outer Element Linear Power for Bundle XY
Table 4b: Average Normalized Outer Element Linear Power for Bundle AAH
Table 4c: Average Normalized Outer Element Linear Power for Bundle GF
Table 5a: Normalized Outer Element Peak Linear Power For Bundle XY
Table 5b: Normalized Outer Element Peak Linear Power For Bundle AAH
Table 5c: Normalized Outer Element Peak Linear Power For Bundle GF
Table 6a: Normalized Outer Element Maximum Sustained Linear Power for Bundle XY
Table 6b: Normalized Outer Element Maximum Sustained Linear Power for Bundle AAH

Table 6c: Normalized Outer Element Maximum Sustained Linear Power for Bundle GF
Table 7: Post-Irradiation Mid-Pellet Sheath Diameter and Diameter Changes
Table 8: Summary of Pellet-Interface Ridge Height and Diameter Changes
Table 9: Summary of Maximum Bow Measurements for Bundles XY and AAH (mm)
Table 10a: Summary of Gas-Puncture Analysis for Bundles XY and AAH
Table 10b: ummary of Gas-Puncture Analysis for Bundle GF
Table 11: Summary of UO2 Grain Size Measurements (micro-m)
Table 12: Summary of Zirconium Oxide Thickness measurements (microns)
Table 13: Summary of Sheath Hydrogen Analysis for Bundle GF
Table 14: Summary of Graphite Coating Survey (%)
Table 15: Summary of Chemical Burnup Measurements
Figures folder contains individual TIF and PNG versions of the 37 figures
AECL-11454 reference
AECL-10636 reference
report XY_AAH_GF_Report.txt in an ASCII file format (no figures included)
README.TXT  README file
XY_AAH_GF.PDF: combines the report, tables and figures (but not the ancillary
data)
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17. CATEGORIES
  • Y. Integral Experiments Data, Databases, Benchmarks

Keywords: CANDU, fission gas release, uranium dioxide.