Energy From Thorium Discussion Forum

It is currently Dec 16, 2017 12:30 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 100 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7  Next
Author Message
PostPosted: Sep 16, 2016 10:30 pm 
Offline
User avatar

Joined: Nov 30, 2006 3:30 pm
Posts: 3353
Location: Alabama
I talked a bit with Jeff Latkowski of TerraPower last week, and asked him about the salt formulation they plan to use. It is a ternary mixture of UCl4-UCl3-NaCl with mole fractions of about 71-20-9. I asked Latkowski about the stability of UCl4 and the potential for corrosion but he said they planned to use molybdenum for the reactor vessel. I've never seen a ternary diagram for this salt mixture before.


Top
 Profile  
 
PostPosted: Sep 18, 2016 9:15 pm 
Offline

Joined: Nov 14, 2013 7:47 pm
Posts: 570
Location: Iowa, USA
Kirk Sorensen wrote:
... he said they planned to use molybdenum for the reactor vessel.


Would that be pure molybdenum? An alloy like chromoly steel? We used chromoly for making the frame on the solar car when I studied at ISU. It's not terribly expensive, easily weldable, strong, relatively light, somewhat resistant to corrosion, and doesn't fatigue like aluminum, which makes it popular for things like bicycle frames. I have a feeling though that they are using something quite different. Did they provide any other details on the composition of the reactor vessel material? I'm just curious.

Also, if you don't mind sharing, how does this material compare to the materials used in a LFTR reactor vessel? I'm trying to get an idea on how much more difficult it would be to build a fast spectrum chloride reactor compared to a thermal spectrum fluoride reactor, both in cost and in ease of manufacture.

If they are using steel and the molybdenum content is less than 7% then that is probably quite expensive but still off the shelf material. If this is something else then I suspect this is going to be very difficult to obtain. If this is a nickel alloy then its not all that different than what would be used in LFTR, no?

_________________
Disclaimer: I am an engineer but not a nuclear engineer, mechanical engineer, chemical engineer, or industrial engineer. My education included electrical, computer, and software engineering.


Top
 Profile  
 
PostPosted: Sep 20, 2016 9:43 pm 
Offline
User avatar

Joined: Jul 14, 2011 9:22 pm
Posts: 33
Location: Forest Park, GA
Kirk Sorensen wrote:
... he said they planned to use molybdenum for the reactor vessel.


Kurt Sellner wrote:
Would that be pure molybdenum? An alloy like chromoly steel?


We did our senior design on molten chloride reactor designs. Molybdenum is fairly noble to chloride salts itself, but has very poor metallurgical characteristics. I happened to stumble upon a high molybdenum alloy called TZM (Titanium-Zirconium-Molybdenum) that has greater than 99% Mo, but with suitable workability and of course refractory properties.

Barring something unforeseen, such as an odd catalyzed corrosion reaction, I would think an alloy such as this would be what is called for in chloride designs.

There is, however, the case of neutron activation in the Molybdenum creating Technetium, but that comes down to how long after shutdown does one need to be able to perform maintenance.


Top
 Profile  
 
PostPosted: Sep 20, 2016 10:14 pm 
Offline

Joined: Nov 14, 2013 7:47 pm
Posts: 570
Location: Iowa, USA
TZM sounds like a very interesting material. Do you have an order of magnitude estimate of its cost? Or, how it compares to the nickel alloys that have been proposed for LFTR?

_________________
Disclaimer: I am an engineer but not a nuclear engineer, mechanical engineer, chemical engineer, or industrial engineer. My education included electrical, computer, and software engineering.


Top
 Profile  
 
PostPosted: Sep 20, 2016 10:35 pm 
Offline
User avatar

Joined: Jul 14, 2011 9:22 pm
Posts: 33
Location: Forest Park, GA
I'm not exactly sure on the price of TZM. I saw one manufacturer in China that said it's about 30% more than plain Molybdenum, and about another 15-20% more to machine.

I would think that the price would be less than that of the nickel superalloys, but maybe more than the normal stainless steel grades.


Top
 Profile  
 
PostPosted: Sep 21, 2016 4:16 pm 
Offline
User avatar

Joined: Nov 30, 2006 9:18 pm
Posts: 1954
Location: Montreal
I thought that the "T" in TZM stood for Tungsten.
Maybe a different TZM then ? Thnx


Top
 Profile  
 
PostPosted: Sep 21, 2016 11:07 pm 
Offline
User avatar

Joined: Jul 14, 2011 9:22 pm
Posts: 33
Location: Forest Park, GA
The titanium and zirconium are in there for precipitation and solution strengthening. The carbides formed inhibit defect migration thus raising the recrystallization temperature.

There are Mo-W, but adding W to the alloy mainly serves to increase its strength at high temperature, which Ti & Zr do adequately by themselves. TZM is a fairly established alloy having been used in industry for decades.

ORNL apparently considered it for use in salt processing equipment and had it tested with FLiBe + ThF4 and UF4. They concluded that it was similar to pure Mo in performance and should function adequately for the considered use:

Quote:
On the basis of this single test, the magnitude and mechanism of corrosion indicate no serious problems for long-term use of TZM alloy in the MSBR vacuum distillation processing scheme. However, the strength properties of the TZM alloy would approach those of unalloyed molybdenum as salt exposure time increased.


http://moltensalt.org/references/static ... M-2724.pdf


Top
 Profile  
 
PostPosted: Sep 27, 2016 12:24 pm 
Offline
User avatar

Joined: Oct 06, 2010 9:12 pm
Posts: 136
Location: Cleveland, OH
Kurt, Vince,

Have you seen this forum thread on the alloy: http://energyfromthorium.com/forum/viewtopic.php?f=64&t=3497

Jim


Top
 Profile  
 
PostPosted: Oct 05, 2016 1:39 pm 
Offline

Joined: Jan 21, 2008 9:12 pm
Posts: 309
Location: idaho falls
I spent most of yesterday going over TERRAPOWER's MSR patent application . ( MOLTEN NUCLEAR SALTS AND RELATED SYSTEMS AND METHODS, Cisneros et. al., applicant TERRAPOWER LLC, 30Jun16 http://www.freepatentsonline.com/y2016/0189813.html)

It's an impressive example of its genre. I expect that if anyone here in the "Western world" is going to win the MSR startup sweepstakes, it's going to be TERRAPOWER.

However, it's written in a way that makes even my eyes glaze over though not nearly as much so as did those generated by one of its competitor's ( Elysium's) lawyers about stuff that I had discussed with them. To me, the whole “startup” approach to nuclear reactor development is BS. Nuclear reactors aren’t "apps" and governments must actively support their development .

I'm soon going to have a chance to respond to the reviewers of a paper I wrote describing the virtues of two isobreeders (MSFR &MCFR) I’ve discussed in other threads. If accepted, my "revised" MS may include a revised title along with a generic description of the sort of "breed and burn" reactor that I feel that TERRAPOWER’S patent application is championing.

Please read through the stuff below & give me your opinions of whether or not I've characterized MCFR "breed & burn" correctly.

“The choice of which sort of fast molten salt reactor should be employed to solve mankind’s future energy needs will ultimately depend upon what characteristics are deemed most important to the decision makers. For instance, if it’s absolutely verboten to have uranium enriched beyond 20% anywhere within the system at any time, the reactors would have to be bigger than would be the case if higher enrichments are allowed. Similarly, if continuous “salt seeking” fission product removal (steady state operation) is considered too troublesome for/by utility owner/operators to implement, reprocessing could be put off for long periods by increasing both the size of the reactors and the amount of startup fissile in them.

Here’s an example based upon TERRAPOWER’s patent application. While that document does not contain examples that are simultaneously complete & specific, it reveals sufficient information to derive such a scenario’s key characteristics.

That document contains a plot of keff vs time (figure 5) for a “large” reactor having an initial fuel salt comprised of 34 mole% uranium trichloride in 66 mole% NaCl and producing either 5.8 (“502”) or 3.42 (“504”) GWt. Its assumptions apparently include no reprocessing other than noble metal scum removal and inert gas sparging and that the only addition to the system is that of sufficient depleted uranium trichloride to fix the concentration of fertile 238U throughout the entire 40 or 70 year “burn” period.

Other information in the application suggests that the uranium’s initial enrichment would be between 11 and 20%, probably about 15%.The description accompanying its figure5 states that uranium “burnup” for its 70 year , 3.42 GWt scenario averages 43% until FP build-up finally stops it which, in turn, translates to generating about 52 times as much heat energy per kg/“raw” uranium as would an equally powerful “GEN III” LWR { 52= .43/(3.42*0.389/160) where “.389” mass of fissile consumed in generating 1 GWt-year & “160” = tonnes of raw uranium consumed/GWe (about 3 GWt) by a modern LWR}.

What else can be derived from that disclosure?

First, since each fission event generates ~3.2E-11 J, generating 3.42 GWt of power for 70 years would require the fissioning of ~93.2 tonnes { ((70*365*24*3600*3.42E+9/3.2E-11)/6.02E+23)*238/1000000} of uranium and its transmutation products. Since 43% of the total uranium either in or added to the system is fissioned, the reactor’s fuel salt initially must have contained ~123 tonnes of uranium {(1-0.43)*93.2/0.43}. Further ball park calculations suggest that a 650°C , 34 mole% UCl3, fuel salt would contain about 1.7 g of uranium/cm3 which, in turn suggests a fuel salt volume of ~ 72.7 m3 {123/1.7} . Since about 9 m3 of out-of-core salt volume would be required for the EU’s 3 GWt MSFR’s pumps, pipes, heat exchangers, etc., this example’s slightly more powerful reactor should require about 10m3 which suggests a reactor tank/core volume of about 63 m {72.7-10}. That size figure is about 7 times that of the EU’s basis MSFR and four times that of the’s steady state MCFR isobreeder that Ondrej Chvala & I dreamed up. Assuming 15% enrichment, TERRAPOWER’s “breed and burn” reactor’s startup fuel would contain about 18.5 tonnes of 235U which is about twice that of the MCFR isobreeder and over three times required by the EU’s basis MSFR or a modern full-sized LWR.

From the standpoint of a typical businessman or politician, “breed and burn” reactor scenarios are probably more attractive than anything assuming steady-state operation because most of their waste management and reprocessing issues are “kicked a long ways down the road”. From either humanity’s or the Earth’s standpoint, they are all equivalent over the long haul because any of them could provide us with 30,000 GWe worth of cheap GHG-free power for millions of years. The biggest “real” downside of such “easy” scenarios is that they would require more startup fissile & therefore take longer to attain such a utopian (happy) steady-state condition.”

_________________
Darryl Siemer


Last edited by darryl siemer on Oct 11, 2016 12:39 pm, edited 1 time in total.

Top
 Profile  
 
PostPosted: Oct 05, 2016 8:16 pm 
Offline
User avatar

Joined: Nov 30, 2006 9:18 pm
Posts: 1954
Location: Montreal
Thanks Darryl.

These patent documents seem to be good at generalities, but not so good at design specifics.

Their intent seems to be to cover as wide a range of designs as possible.

Good luck trying to get any meaningful concepts out of them :lol:


Top
 Profile  
 
PostPosted: Oct 06, 2016 1:37 am 
Offline

Joined: Jan 21, 2008 9:12 pm
Posts: 309
Location: idaho falls
jaro wrote:
Thanks Darryl.

These patent documents seem to be... :


Agreed - patent applications are written to claim as much as possible, not to inform their readers about the subject. However, it's sometimes possible to put together a useful conclusion from what is revealed as I believe I've done in this particular instance.

Unfortunately the ABSTRACTS of many of the papers published in paywalled technical journals seem to be written in the same fashion.

_________________
Darryl Siemer


Top
 Profile  
 
PostPosted: Oct 06, 2016 6:29 pm 
Offline

Joined: Jan 21, 2008 9:12 pm
Posts: 309
Location: idaho falls
Kirk Sorensen wrote:
I talked a bit with Jeff Latkowski.... I've never seen a ternary diagram for this salt mixture before.


The patent disclosure in the first posting I made yesterday has that ternary phase diagram.

I've checked out that fuel salt composition (71UIV/20UIII/9Na) with both nickel & Mo from 400 to 700C with HSC 6.1 - your instincts are right, it's 'way too corrosive for either of them. That's why Taube et al assumed that UIII>>>UIV.

Have you ever seen a UIII/Ca/Na chlorides phase diagram?

_________________
Darryl Siemer


Top
 Profile  
 
PostPosted: Oct 09, 2016 9:52 pm 
Offline
User avatar

Joined: Nov 30, 2006 3:30 pm
Posts: 3353
Location: Alabama
In this patent disclosure:

http://www.freepatentsonline.com/20160189813.pdf

they describe a 71-17-12 UCl4-UCl3-NaCl salt mixture in Figure 4.


Top
 Profile  
 
PostPosted: Oct 10, 2016 10:02 am 
Offline

Joined: Jan 21, 2008 9:12 pm
Posts: 309
Location: idaho falls
Kirk Sorensen wrote:
In this patent disclosure:

http://www.freepatentsonline.com/20160189813.pdf

they describe a 71-17-12 UCl4-UCl3-NaCl salt mixture in Figure 4.


I've seen that one. The problem with that mixture is that thermodynamic calculations indicate that it's too corrosive (oxidizing) for even pure Mo metallic reactor/HX parts. There's been an investigation of Mg/Na/UIII chloride salts that concluded that it wouldn't work (AnIII solubility too low) but as far as I know, no one has looked at the the Ca/Na/UIII system yet -the object is to lower the melting point.

_________________
Darryl Siemer


Top
 Profile  
 
PostPosted: Oct 10, 2016 10:47 am 
Offline
User avatar

Joined: Nov 30, 2006 3:30 pm
Posts: 3353
Location: Alabama
darryl siemer wrote:
I've seen that one. The problem with that mixture is that thermodynamic calculations indicate that it's too corrosive (oxidizing) for even pure Mo metallic reactor/HX parts.


I raised that issue with Jeff Latkowski of TerraPower immediately after he told me about the salt composition but he dismissed the concern, saying that molybdenum looked like it would be good enough for the mixture. I'm simply not enough of a chemist, nor do I have enough experience with chloride salt mixtures to know if that's an accurate statement or not.

But questions like this really make me think that we need the equivalent of the Aircraft Reactor Experiment for several chloride salt mixtures. Just to check if they can achieve criticality and run with some degree of chemical stability over a time interval.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 100 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 guests


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