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| Program name | Package id | Status | Status date |
|---|---|---|---|
| IFPE/AECL-BUNDLE | NEA-1596/03 | Arrived | 16-JAN-2023 |
Machines used:
| Package ID | Orig. computer | Test computer |
|---|---|---|
| NEA-1596/03 | Many Computers |
Prototype CANDU Fuel bundles for the CANDU6 (bundle NR) and Bruce (bundle JC) reactors were irradiated in the NRU experimental reactor at Chalk River Laboratories in experimental loop facilities under typical CANDU reactor conditions, except that they were cooled using light water.
Bundle JC was a prototype 37-element fuel bundle for the Bruce-A Ontario Hydro reactors. This pressurized heavy water reactor (PHWR) design utilizes a heavy water moderator and pressurize heavy water coolant. For irradiation in the NRU reactor, the centre fuel element was removed and replaced by a central tie rod for irradiation purposes in the vertical test section. Coolant for the test was pressurized light water under typical PHWR conditions of 9 to 10.5 MPa and 300°C.
The fuel elements used 1.55 wt% U235 in U uranium dioxide fuel and were clad with Zircaloy-4 material. The bundles' elements were coated with a graphite coating. The fuel is somewhat atypical of 37 element-type fuel since the length to diameter ratio (l/d) is large (1.73) due to the pellets being ground down from a OD of 14.3 mm to 12.12 mm. The outer element burnup averaged approximately 640 MWh/kgU on discharge. Outer element powers varied between 57 kW/m near the beginning of life and 23 kW/m at discharge. Due to the long irradiation, the bundle experienced 153 short shutdowns, and 129 longer duration shutdowns.
No element instrumentation was used during the irradiation. However, the bundle was subjected to extensive post-irradiation examination (PIE) that included dimensional changes, fission gas release, fuel burnup analysis, and metallography that included grain size measurement.
Bundle NR was a prototype 37-element fuel bundle for the CANDU 600 reactor. This pressurized heavy water reactor (PHWR) design utilizes a heavy water moderator and pressurized heavy water coolant. For irradiation in the NRU reactor, the centre fuel element was removed and replaced by a central tie rod for irradiation purposes in the vertical test section. Coolant for the test was pressurized light water under typical PHWR conditions of approximately 9 to 10.5 MPa and 300°C. The fuel elements used 1.41 wt% U235 enriched UO2 fuel pellets and were clad with Zircaloy-4 material. The inner sheath surface was coated with a graphite layer. Three types of pellet-stack-to-end-cap geometries were used for the outer elements: a 350 mm3 plenum insert (six elements), a 580 mm3 plenum insert (six elements), and no plenum insert (six elements). Intermediate and inner element rings had no plenum insert.
Outer element burnups reached average measured burnups of 235 MWh/kgU. Outer element powers were steady during the irradiation and ranged between 58 and 62 kW/m during the irradiation.
No element instrumentation was used during the irradiation. However, the bundle was subjected to extensive post-irradiation examination (PIE) that included dimensional changes, fission gas release, and fuel burnup analysis.
Keywords: burnup, fission gas release, fuel elements, heavy water moderated reactors.
