APR 1400 for UAE- mixing vanes integrity?

[davefitz]

After reading of the success of the Korean APR 1400 to UAE yesterday, I glanced at the basic design configuration of fuel rod assy posted at the KHNP site. It appears that CHF critical heat flux and DNB departure from nucleate boiling is avoided by use of external turbulence promoters, aka mixing vanes.

It would seem that the long term integrity of the attachment of these mixing vanes to the structure would be a weak link in the design- fluid elastic vibrations of these vanes might be expected to lead to macro cracks at the weld regions after (N) vibration cycles.

Does anyone know if these were tested for the equivalent 60 yr service life?

 

[EdStainless]

I don't know about this specific component. There are a few other places within the core assembly that could prove problematic over long service. Friends of mine in the Korean Nuc industry have told me that some of these are designed with 40:1 or greater factors.
They cut corners in other places.

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Plymouth Tube

 

[gmax137]

hmmm ... I don't think mixing vane grids are a new idea.

 

[gmax137]

Mixing vane grids have been used in power reactors since the mid 1970s (if not earlier).

The vanes are formed as 'tabs' as part of the grid - they aren't welded on; and (maybe) most important, they don't have a 60 year service life, they are part of the fuel bundle and therefore have to last only 2 or 3 cycles (say 3 to 5 years).

 

[davefitz]

Thanks, gmax137