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Program name | Package id | Status | Status date |
---|---|---|---|
IFPE/EXP-BDL-406 | NEA-1841/02 | Arrived | 16-JAN-2023 |
Machines used:
Package ID | Orig. computer | Test computer |
---|---|---|
NEA-1841/02 | Many Computers |
Experiment EXP-BDL-406
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
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
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
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
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 (at) aecl.ca).
Keywords: CANDU, fission gas release, uranium dioxide.