CANFLEX bundle

The CANFLEX bundle design forms the basis of the both the fuel design adopted for LVRF (Section 15.7.2) and for the fuel design in the new 1000 MW Advanced CANDU Reactor. 

While the CANFLEX bundle achieves some of these objectives, it has two different rod diameters, and hence does not meet objective 3. Hence, a new design was developed. 

The CANFLEX bundle is the reference for fhe DUPlC cycle, having 20% lower peak linear element ratings than a 37-element bundle, and improved thermal-hydraulic performance. 

CANFLEX CANDU FLEXible fueling—an advanced fuel bundle design... 

A 52-element bundle geometry was chosen due to good symmetry and compactness of the array. The reduction in the number of endplugs and endplates, due to the double-length bundle, gives a uranium credit that can be used to increase the bundle uranium mass. The pellet diameter is very similar to that of the smaller CANFLEX elements, but with a slightly greater clad thickness and gap clearance compared to the standard 37-element bundle. 

Alternatively, enrichment could be used to flatten the channel and bundle power distributions in the core without increasing reactor power. Using CANFLEX, for example, as the carrier for SEU, peak linear element ratings could be reduced to below 40 kW/m, resulting in virtually no fission gas release during normal operation, and increased operational and safety margins. 

Hastings, I.J., A.D. Lane, and P.G. Boczar. 1989. CANFLEX - An Advanced Fuel Bundle for CANDU, International Conference on Availability Improvements in Nuclear Power Plants, April 10-14, Madrid, Spain, also AECL-9929. 

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