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PostPosted: Jul 06, 2016 2:41 pm 
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Thanks for the links and the heads-up, Burghard.
WHY NOT THORIUM FIRST?

The TAP MSR’s primary innovations, a novel combination of moderator and fuel salt, can also be adapted for use with thorium. Transatomic Power believes that the thorium fuel cycle holds theoretical advantages over uranium in the long run because of its generally shorter half-life waste, its minimization of plutonium from the fuel cycle, and its greater natural supply. However, we chose to start with uranium for several reasons: (1) there is a great deal of SNF, and we want [to] harness its remaining energy; (2) the industry already has a commercial fuel cycle developed around uranium, which makes it cheaper to use uranium as fuel; and (3) we already greatly expand the energy potential of existing uranium supplies.

While thorium reactors contain minimal plutonium, they do have a potential proliferation vulnerability because of the protactinium in their fuel salt. Protactinium has a high neutron capture cross section and therefore, in most liquid thorium reactor designs, it must be removed continuously from the reactor. This process yields relatively pure protactinium, which then decays into pure U-233. By design, the pure U-233 is sent back into the reactor where it is burned as its primary fuel. The drawback, however, is that U-233 is a weapons-grade isotope that is much easier to trigger than plutonium. We believe that the proliferation objection to liquid thorium is actually related to protactinium-233 in the thorium portion of the reactor. If this can be extracted chemically, it decays quickly into pure U-233.

It is possible to denature the U-233 by mixing it with other uranium isotopes, or to modify the design to further reduce diversion risk, but additional research is required to implement these measures in thorium molten salt reactors. Some may discount the proliferation risk of the thorium fuel cycle because the U-233 in the reactor would be mixed with U-232, rendering it a poor source for proliferation purposes. However, it is the decay products of U-232 that produce high-energy gamma radiation that renders it difficult to handle. Therefore, even with this mixture, it may be possible to chemically extract the decay products before they become gamma emitters, leaving unprotected weapons-grade uranium.
This thorium proliferation risk is a heated debate. Our host has correctly pointed out that a pure U-233 bomb has NEVER been made. The Teapot MET test was a Pu-239/U-233 mixed pit (as far as is reported in the public domain) and under-performed. Of over 10,000 nuclear warheads in the world today among the nuclear nations, how many are pure U-233 warheads? Zero.

If pure U-233 is such a great proliferation risk, then why has it never been used for a bomb? Lars said the terrorists have many other better and more ready avenues for killing innocent people and for what end? So far, the odds of another nuclear detonation being used on innocents is . . . ~zero. It's been done only two times and that's all it'll ever be done. The bomb will never be used in war again. The threat is bad enough!

But if Flibe Energy is successful with their LFTR, maybe we entomb all the SNF anyway, rather use clean-burn thorium in FE LFTRs instead, and then TAP goes out of business? So. Another clash of the advanced nuclear reactor titans.

How does TAP clean their salt (if at all) and what is the end of their fuel cycle? No plan for the significant output of TAP WAMSR radiotoxic wastes? What is the TAP plan for getting at the SNF?

Section 2.3 Salt Formulation, 2. wrote:
FLiBe contains beryllium, which can lead to chronic berylliosis in a significant portion of the population. Forgoing beryllium use thus imparts an occupational health benefit as well.
Dr. Edgar Vidal, Materion, Inc., presently the only beryllium supplier in the U.S., has addressed this concern amply. The BeF2 product is not a berylliosis hazard. Fluoride salts are very stable (fluorine is the most electronegative element in nature, and happens to be invisible to neutrons); it so happens to be the step just before the expensive process of defluorination to beryllium metal. The extremely hazardous TAP WAMSR will have bigger fish to fry than to worry about beryllium. But do the thermal and neutronic benefits of 7LiF-BeF2 (2:1) outweigh its share of the overall reactor costs? They must otherwise Oak Ridge would not have used beryllium in the first place. But FE and TAP are going rounds on neutron moderation. How exciting!

One thing is lithium. Everyone wants highly-depleted lithium. TAP nonchalantly remarks that lithium-6 generates the troublesome tritium. What about its neutron-eating in the reactor? They're not worried about Li-6 interfering with their reactor neutronics? Either way, will the Chinese method using ionic liquids rule for HD lithium production? They've captured the world's REEs. Will they win the MSR race?

The whole world doesn't know there's another but very quiet race to Moon all over again and it's fluid-fueled reactors!

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PostPosted: Jul 06, 2016 8:38 pm 
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Burghard wrote:

Ya.... had a quick read through it.
Interesting.
Looks like they're slowly moving towards a fast reactor design, like EVOL's MSFR.

It's pretty amazing - if true - that they can get a 90% fuel salt reactor critical on 5% LEU !
Fast reactors typically require about 12% LEU minimum.

Then they start adding SiC-clad moderator rods full of ZrH, to gradually shift the spectrum from fast to thermal.
I'm sure the NRC will love that !
Not to mention all the extra hardware complications, that could be avoided by just going straight to the EVOL design (plus far higher burnup to boot!).

Makes you wonder why they still bother pushing the TAP concept.
Give it up already !


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PostPosted: Jul 06, 2016 11:51 pm 
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I also did a quick read through and the papers bring up more questions than answers. To me it seems like they spend more time bad mouthing the competition than in describing the merits of their own design, perhaps that's just how one makes a sale. What bothers me is that much of the bad points they give about the competition look like straw man arguments. They mention issues like beryllium, tritium, U-233, proliferation, and regulations in a way that frames them in a really bad light but even I, with my limited knowledge of nuclear physics, don't believe everything they say.

I've seen Transatomic give presentations before but never in a forum where they'd field questions from a room full of people with doctorates and masters in engineering and physical sciences. It would be interesting to see them present at a Thorium Energy Alliance Conference, which is unlikely. First, they do not intend to use thorium as a primary fuel and so presenting at TEAC would be the wrong crowd. If they did put thorium in their reactors it would be after they've proven their waste annihilating designs and years later they wanted to show they could breed thorium too. Second, I believe that if they did present at TEAC or a similar forum that they'd get questions that they'd rather not answer. As in if presented to a crowd knowledgable on the subject the FUD from their papers would be exposed as such, and done so in a way that their fear mongering is undeniably built of straw men.

This also confirmed something I suspected earlier, they are running their reactors with "epithermal" neutrons. I suspected earlier that they'd claim to have found some sweet spot between thermal neutrons and fast neutrons so that they can get the benefits of both. This sounds too good to be true and I'm sure someone will point out that this is in fact too good to be true.

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PostPosted: Jul 07, 2016 7:02 am 
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A graphic in the appendix clearly shows the shift from fast to thermal spectrum, over the life of the core.....


Attachments:
TAP_BOL-EOL_spectra_Fig-B1_July-2016.jpg
TAP_BOL-EOL_spectra_Fig-B1_July-2016.jpg [ 99.67 KiB | Viewed 2660 times ]
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PostPosted: Jul 07, 2016 1:32 pm 
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jaro wrote:
A graphic in the appendix clearly shows the shift from fast to thermal spectrum, over the life of the core.....


Is this done by inserting the movable moderator rods more or less? This seems to be a new feature of the reactor they added only recently.


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PostPosted: Jul 07, 2016 2:56 pm 
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Yes, this is anew feature, at least in terms of previously published white papers.
Attachment:
TAP_movablemoderatorrods_Fig-5_July-2016.jpg
TAP_movablemoderatorrods_Fig-5_July-2016.jpg [ 103.42 KiB | Viewed 2626 times ]


The change in fuel salt volume (relative to moderator) is also illustrated.
Attachment:
TAP_SVF_Fig-6_July-2016.jpg
TAP_SVF_Fig-6_July-2016.jpg [ 81.37 KiB | Viewed 2626 times ]


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PostPosted: Jul 07, 2016 4:12 pm 
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The author of this topic, artw, is M.I.A. Thanks to others for reviewing the TAP designs.

Kurt, I agree with your TEAC challenge to TAP. But will members here agree the goals of a WAMSR are good?

Here at Crystal River 3 (Duke Energy), there are 1244 SNF assembles with 583.6 tonnes of heavy metal stored in pools to be moved to dry storage (SAFSTOR). (See: Preliminary Evaluation of Removing Used Nuclear Fuel from Shutdown Sites.)

If a TAP WAMSR existed, worked, and was licensed for use, and CR3 still has its SNF by that time, building and operating the TAP WAMSR there would be a win-win-win situation: utility profits, abundant non-emitting energy for Florida consumers, and a reduction in the national SNF inventory.

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PostPosted: Jul 08, 2016 9:15 am 
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It is definitely desirable to get more power out of used fuel. However there are two requirements, besides the NRC clearance, perhaps before it, which need to be met.
1. Lower cost of reactor per MW.
2. An economical processing to reduce the fission product poisons.
In recent times, only the Chinese built the first reactors.
Indian PFBR being the honourable exception.


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PostPosted: Jul 11, 2016 2:02 pm 
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Tim Meyer wrote:
Kurt, I agree with your TEAC challenge to TAP. But will members here agree the goals of a WAMSR are good?

I do not believe that anyone will claim that Transatomic's goals are bad, except people that see anything "nu-ku-lar" as bad. It appears to me that the largest point of contention is if the reactor designs they propose will actually work. As jagdish points out even producing a working reactor is insufficient, the reactor must also prove to be economical, safe, and generally better than alternatives.

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PostPosted: Jul 11, 2016 3:54 pm 
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"nu-ku-lar" . . . that is some funny stuff there, sir. Dude! I'm SO laughing! (I say nu-cle-ar, Bush says Nu-cu-lar--you went for the "k" that's better.)

Well, good, on the TAP WAMSR. Exactly! And I bet this is foremost on the mind of one of it's inventors and co-founders. How many other women nuclear physicists are in the molten salt game? Most are men. Not that gender matters. But it is fascinating from the outside looking in. Have you seen her? Wham, sir!

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PostPosted: Jul 13, 2016 3:14 am 
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jaro wrote:
Burghard wrote:

Ya.... had a quick read through it.
Interesting.
Looks like they're slowly moving towards a fast reactor design, like EVOL's MSFR.

It's pretty amazing - if true - that they can get a 90% fuel salt reactor critical on 5% LEU !
Fast reactors typically require about 12% LEU minimum.

Then they start adding SiC-clad moderator rods full of ZrH, to gradually shift the spectrum from fast to thermal.
I'm sure the NRC will love that !
Not to mention all the extra hardware complications, that could be avoided by just going straight to the EVOL design (plus far higher burnup to boot!).

Makes you wonder why they still bother pushing the TAP concept.
Give it up already !


Given their analysis on ZrH moderator effectiveness, is there merit in a thermal, single fluid design (ie like Terrestrial and ThorCon), but using ZrH coated in SiC (or something else) instead of the graphite. (ie not trying to do complex fast - thermal shifts).

Their central USP is that they are claiming the core can have - by volume, 50% salt, 50% moderator, compared to 10% salt, 90% moderator for a graphite design. That would
- Make the core 1/5 the volume for the same power output. (Making a 250MWe core + primary loop easily truck transportable)
- Make the core last longer.
- Provide an additional safety feature (the ZrH dissociation).
- Make disposal easier (the moderator will have fewer impregnated fission products)

What would be the disadvantages of that?


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PostPosted: Jul 19, 2016 3:15 pm 
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Quote:
What would be the disadvantages of that?


Maybe there will be a chemical risk with the presence of hydrogen (although Transatomic said that the quantity of hydrogen is too small to cause an explosion, this is still bad PR).

Also there is less thermal inertia, but this is maybe not a big problem for the concepts which use drain tanks.

If it works the ZrH moderators rods will permit to greatly increase the power of the units, this improves the economic competitiveness of the reactors.


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PostPosted: Nov 18, 2016 3:20 pm 
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And there is one more update:
http://www.transatomicpower.com/wp-cont ... r-v2.1.pdf
http://www.transatomicpower.com/wp-cont ... r-v1.1.pdf


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PostPosted: Nov 18, 2016 3:39 pm 
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Burghard wrote:
http://www.transatomicpower.com/wp-content/uploads/2015/04/Neutronics-White-Paper-v1.1.pdf


Figure 8 of this paper (Conversion ratio as a function of burnup) demonstrates the failure of their design, even if one assumes that they will succeed with ZrH moderator and their moveable moderator rod strategy. The reactor doesn't breed (CR > 1.0) which is no surprise to anyone who knows anything about breeding ratios in thermal spectra. Because it doesn't breed they cannot achieve their stated objective of burning up all the spent nuclear fuel that they have claimed since the outset.


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PostPosted: Nov 18, 2016 6:19 pm 
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Kirk Sorensen wrote:
Burghard wrote:
http://www.transatomicpower.com/wp-content/uploads/2015/04/Neutronics-White-Paper-v1.1.pdf


Figure 8 of this paper (Conversion ratio as a function of burnup) demonstrates the failure of their design, even if one assumes that they will succeed with ZrH moderator and their moveable moderator rod strategy. The reactor doesn't breed (CR > 1.0) which is no surprise to anyone who knows anything about breeding ratios in thermal spectra. Because it doesn't breed they cannot achieve their stated objective of burning up all the spent nuclear fuel that they have claimed since the outset.

)
TAP's white paper is pretty confusing to me. For example, while it's apparently a once-through reactor, they don't explain how it actually runs. Its authors point out that FP removal is helpful but don't say what if any degree of FP removal is assumed in their examples (Tables & figures).

Can't they see that their Figure 4 indicates that TAP's reactor would work much better without its special moderator rods than with them (fast is better in every respect - esp for "waste" reduction - & no rods is fastest )?

Also it seems strange that any fluoride salt based U breeder would exhibit a CR >1.5 regardless of how moderated it is (e.g., Fig 4's 1.2% 235U case with SFV>.9).

Can anyone explain what's meant by "CReff "? Adding the fraction of fissile in whatever's being fed to the reactor (continuously or just up front -they don't say) to its CR doesn't seem to make any sense. Is the CR referred to in Fig 8, the "real" CR or CReff?

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