RE: [cdn-nucl-l] RE: Nuclear Renaissance (Dan Meneley)

["Jaro Franta" <jaro-10kbq@sympatico.ca>]

Just a quick comment.....

Rod Adams wrote on January-17-10 7:23 PM

<snip>How can you improve on the proven record of Gen II reactors? Sure, the
models "prove" a higher level of safety, but even TMI, which actually melted
a large portion of the core, would never have needed a "core catcher". The
fact that systems without that expensive addition would not be licensed in
France is typical protectionism, not safety.<end>

Thanks Rod,

I'm not sure that this particular addition is what makes Areva's EPR so
expensive, or that it is "not needed".

On the first aspect, "core catchers" appear to be gaining *regulatory*
favour in places other than France as well:  GE's ESBWR is supposed to have
one (the BiMAC, or "Basemat Internal Melt Arrest and Coolability device"),
and recent models of Russian VVERs (ie. model V-320) have them too --
notably the two units recently completed in Tianwan, and I believe the
Indian VVERs currently under construction as well.... (its a basket made of
Al2O3-Fe2O3-steel mixture and filled with a special material compound).
See for example the papers & presentations from the OECD NEA CSNI Workshop
on Severe Accident Management (Paul Scherrer Institute, September 2001).

Westinghouse's AP600 was provided with features that assure in-vessel
retention (IVR) and coolability, and the AP1000 has followed the same
approach -- ie. not core catchers, but very different from TMI-type Gen-II
plants nevertheless.

IVR is easier to implement in smaller reactors -- hence the trend to core
catchers in the large Gen-III+ designs, like the 1600MWe EPR. 
The Westinghouse design is pretty much stuck at a maximum 1000MWe capacity,
precisely because of their Severe Accident Management design....
Conversely, an LWR with capacity comparable to the EPR but no core catcher,
is basically an LWR without Severe Accident Management.
The clear implication of Areva's comments about the Korean APR-1400 is that
it lacks Severe Accident Management.

Anyhow, large double containment domes are more likely to be the bigger cost
culprits.
But these too are becoming the norm for LWRs.
And while this novelty originates from concerns about RB impacts rather than
LOCAs, it is the large internal volume required to deal with PHT fluid
having a large amount of stored energy, that drives the expensive new RB
designs....
This is unlikely to change as long as that PHT fluid is water, or if there
is potential for energy release in sodium-water or even sodium-air
combustion, as in LMFRs.

By contrast, reactors with low-stored-energy PHT systems fit easily into
small RBs -- hence making their reinforcing a relatively low cost
proposition....  and even making underground siting feasible if desired and
if viable in local geologic conditions....

Hopes this clears things up a bit.

Cheers,

Jaro
^^^^^^^^^^^^^^^^^^^^^^^^^