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PostPosted: Oct 01, 2011 10:17 am 
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Cyril R wrote:
Thanks Jaro, that's what I was hoping for. Looks like we can really get started already without waiting for new codes!

Yeah.
The only thing I'm not too sure about is the valve internals.
For example, if its a ball valve, would the ball itself have to be code metal, or would a SiC ball be acceptable ? ....ceramic ball valves are common in industry, but I'm not sure how they're viewed by nuke regulators.
In worst case, the ball would have to be cooled also -- meaning SiC liner of the hole in the ball (certainly doable).


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PostPosted: Oct 01, 2011 11:57 am 
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jaro wrote:
Cyril R wrote:
Thanks Jaro, that's what I was hoping for. Looks like we can really get started already without waiting for new codes!

Yeah.
The only thing I'm not too sure about is the valve internals.
For example, if its a ball valve, would the ball itself have to be code metal, or would a SiC ball be acceptable ? ....ceramic ball valves are common in industry, but I'm not sure how they're viewed by nuke regulators.
In worst case, the ball would have to be cooled also -- meaning SiC liner of the hole in the ball (certainly doable).


We'll use a TRISO pebble. :lol:

But perhaps a closing gate valve is more suited for this application. It has sufficient surface area for cooling. I was hoping to use a magnetic (ie canned) closing gate valve which I believe will work at the reduced temperatures (and if the valve cooling fails the temperature rise will cause the valve to close as well).

Possibly we'll use two different valves for diversity reasons (avoid common mode failure) but I don't think will be necessary for our application.


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PostPosted: Mar 10, 2012 7:57 am 
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Cyril R wrote:
In the USA, nuclear pressure boundary materials
... Any thoughts?

Please pardon the dumb question, but... WHAT pressure boundary? Doesn't ASME presume there is some minimum X hundred psi (Mpa) pressure to bound, not just a pot-o-stuff to hold?

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PostPosted: Mar 10, 2012 8:50 am 
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KitemanSA wrote:
Cyril R wrote:
In the USA, nuclear pressure boundary materials
... Any thoughts?

Please pardon the dumb question, but... WHAT pressure boundary? Doesn't ASME presume there is some minimum X hundred psi (Mpa) pressure to bound, not just a pot-o-stuff to hold?


Yes, if the pressure is low enough, close to atmospheric, then you might argue there is no nuclear pressure boundary. I wonder if this will be allowed by the NRC. They seem to think in terms of nuclear/non-nuclear, boundaries etc, and require certain materials to be used in the different nuclear/non nuclear systems. It would be useful to know how unpressurized reactors are licensed, such as research and isotope production open pool type reactors. Some of these have such a large volume of water in them and such low power output, that any sort of pressurization isn't plausible.


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PostPosted: Mar 07, 2014 3:34 pm 
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This recent paper on the prospect of code-qualifying Hastelloy N could be of considerable interest to the group:


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Swindeman-alloyN-paper.pdf [216.89 KiB]
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PostPosted: Mar 08, 2014 2:15 am 
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Kirk Sorensen wrote:
This recent paper on the prospect of code-qualifying Hastelloy N could be of considerable interest to the group:


Thanks Kirk. This work probably comes from the AHTR need for Hastelloy N vessels.

The question for us is, are we allowed to use subsection NH for the pressure vessel, pumps and heat exchangers? Subsection NB must be used in today's reactors.

NH seems to be not for the RCPB, and NB seems to be not for high temperature service.

The whole section III code structure is written for high pressure medium temperature, basically LWRs.


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