Energy From Thorium Discussion Forum

It is currently Dec 15, 2017 9:12 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 17 posts ]  Go to page Previous  1, 2
Author Message
PostPosted: Dec 28, 2008 7:25 am 
Offline

Joined: Oct 29, 2007 6:27 pm
Posts: 279
Worker related safety is far more difficult then public safety, because then you'll need a geometrical design of your power plant and know the places of precipitation before you can do any dose mapping and so on.

I've also read a lot of safety analysis and the reactivity effects are limited by temperature and so on, so i'm quite confident about control of reactivity excursion. What I wonder about is the effect on heavily irradiated (so embrittled-corroded) materials such as the vessel, piping walls and heat exchangers. And what would happen in the event of a leak in which the 2 phase behavior of the salt becomes dominant. Furthermore the dispersion behavior trough the reactor cell and possible leakages towards the environment from there...and possible effect on other related installations which have a high radio-isotope inventory...

Furthermore how well validated are the codes we have today to simulate those things?

_________________
Liking All Nuclear Systems, But Looking At Them Through Dark And Critical Glasses.


Top
 Profile  
 
PostPosted: Dec 28, 2008 12:47 pm 
Offline

Joined: Jul 28, 2008 10:44 pm
Posts: 3070
STG wrote:
Worker related safety is far more difficult then public safety, because then you'll need a geometrical design of your power plant and know the places of precipitation before you can do any dose mapping and so on.

The general approach is to use robotics instead of people. It won't work all the time but robotics have come a long way since the 1960's. Some of the exposure stories I've read never should have had a worker in there in the first place. For now we need to be aware of worker safety as we design the plant. Once a rough design is in place we can analyse it for worker safety and see if we need to augment the fundamental design to improve worker safety. I don't discount its importance but I think it is premature to evaluate it yet.

STG wrote:
I've also read a lot of safety analysis and the reactivity effects are limited by temperature and so on, so i'm quite confident about control of reactivity excursion. What I wonder about is the effect on heavily irradiated (so embrittled-corroded) materials such as the vessel, piping walls and heat exchangers. And what would happen in the event of a leak in which the 2 phase behavior of the salt becomes dominant.

I'm not sure what you are referring to with the "2 phase" behavior. My thought is that the fuel salt be surrounded completely by blanket salt. (This is somewhat different than the French design). Any leak of fuel salt will go either into the blanket salt or the secondary salt. In either case, we have less fuel salt in the core and the reactivity there will go down. The leaked fuel salt will be diluted with other salts so there will be less reactivity there as well. Any leak of blanket or secondary salt will also dilute the fuel salt. So while no simulations have been done that I know of no leak can increase the reactivity.

STG wrote:
Furthermore the dispersion behavior through the reactor cell and possible leakages towards the environment from there...

There will be the normal triple containment system. Assuming you break through all three layers (an unexplained explosion rips up the inside of the reactor?) then the salt spills onto the floor. Necessarily the fuel and blanket and secondary salts get all mixed so the reactivity isn't an issue. But you have very hot stuff (both thermally and radioactivity wise) all over the place. At this point the reactor is a total economic loss and the goal is to be certain that the public isn't exposed. One would want to be sure there was no water inside the containment structure that could be converted to high pressure steam. In such a disaster, I would presume the gases - especially Kr85 will get loose as well and be inside the containment structure. Pretty grim stuff to be thinking about. One would want to be sure to be able to seal off the containment structure (which I presume is standard design). If the turbines are outside then the secondary salt pipes must pierce the containment walls so they need something fancy - again I presume this is part of standard design.


STG wrote:
and possible effect on other related installations which have a high radio-isotope inventory...
Furthermore how well validated are the codes we have today to simulate those things?

Definitely need to watch what happens to the stored Kr85 and any I129 and design the storage appropriately. I'm thinking it may well be best to store the Kr85 inside the containment structure and put the I129 back into the reactor.

The codes for simulating a MSR aren't ready yet. Simplifying assumptions are made to be able to get approximate results using existing codes. I presume there will need to be serious coding effort done to adjust the codes to support molten salts.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 17 posts ]  Go to page Previous  1, 2

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group