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Small modular reactor design could be a SUPERSTAR
R&D Magazine ^ | Feb 9 2012

Posted on 02/11/2012 7:59:11 AM PST by Wonder Warthog

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To: Wonder Warthog
Thanks to you as well, WW. Sorry to veer OT.

"The most effective "slowing down" material is one that has a high percentage of hydrogen."

So a large quantity of diesel fuel or a big pile of coal would work pretty well? How about boron?

Just trying to figure out where to stand if a neutron bomb goes off in the vicinity. ;)

41 posted on 02/11/2012 12:46:38 PM PST by SnuffaBolshevik (In a tornado, even turkeys can fly.)
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42 posted on 02/11/2012 12:49:57 PM PST by TheOldLady (FReepmail me to get ON or OFF the ZOT LIGHTNING ping list)
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To: SnuffaBolshevik
Boron is a little different because it has an isotope (10B) that has a strong thermal neutron capture cross-section. So it is a question of balance between scattering and absorption, you have to look at both. And as noted with the heavier nuclei it is not just a question of scattering. Heavy nuclei will scatter neutrons. But you want to maximize energy exchange without losing the particle being scattered (neutron). There is a calculation of a (dimensionless) quantity we use in reactor physics (lethargy). Where lethargy gained per collision is large, you have a good moderator.
43 posted on 02/11/2012 1:05:35 PM PST by chimera
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To: Lx
As a publicity stunt, SMUD put a bunch of solar panels on the Rancho Seco property, right on the front lawn of the aux building. Last numbers I saw showed the solar panels generating over their entire lifetime only a small, small fraction of what the nuclear plant did in a single year.

SMUD also went all-in on "efficiency" and "end use management". They learned that hard way that conservation only works if you have something to conserve in the first place.

44 posted on 02/11/2012 1:10:18 PM PST by chimera
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To: chimera

Yes, SMUD did the same thing at their main office off of hwy 50. You can see them from the freeway. I’ve never seen any numbers on how much they produce or how much efficiency is lost as they get older. I think the rule of thumb is a solar cell loses 10% of its efficiency each year.

That’s a good reason to use the boiling oil (or whatever they use) down in Eastern, Southern California. The reflectors track the sun and direct their light onto a boiler, it’s this hot fluid that drives the turbines. I’ve never seen a comparison of its efficiency VS a solar cell. The plant is ugly but who cares? It’s in the middle of the desert. But, I could be convinced to put one next to Jerry Brown’s house.


45 posted on 02/11/2012 1:45:48 PM PST by Lx (Do you like it, do you like it. Scott? I call it Mr. and Mrs. Tennerman chili.)
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To: omega4179
In 1962 at the National Youth Conference on the Atom I heard an Argonne National Laboratory engineer tell me fusion would provide "energy forever," within twenty years.

More recently, the Japanese tech firm Toshiba is developing these distributed nuclear generation units, designed so that they can be lit up, buried, and ignored for the next fifty years or so.

46 posted on 02/11/2012 2:30:47 PM PST by hinckley buzzard
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To: Lx

Fukushima Reactor 1 was designed by GE, built by TEPCO, and began service in 1971. I don’t think that qualifies as “modern,” but opinions may vary.


47 posted on 02/11/2012 2:37:06 PM PST by hinckley buzzard
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To: Wonder Warthog

This experiment in using nuclear power to boil water started in 1942 only for creating and exacting the by-product plutonium, for bomb making. It was billed later as unlimited source of electric power generation as a cover when other countries wanted to join the ‘Mutual Assured Destruction’ (MAD) nuclear race.

Once you start a nuclear reaction, you can’t stop it. The fission may end but decay of parent material into daughter material continues indefinitely (in our time frame).

If you expose a recent spent fuel assembly to air, heat from decaying material reactions will cause it to catch on fire in 15 minutes or less releasing its radioactive contamination. Takes five to ten years for the fuel assembly’s decay reactions to diminish enough to even think about exposing it to air and still you need circulating air to carry off residual heating.

This is why nuclear fuel sits in pools next to the reactors as it must be transferred (moved) and stored underwater at all times, for years. Plus, constant cooling (removal of heat) from the storage pool water or the water will heat up beginning to steam and boil away.

BWR are only about 30% efficient as the quest for more efficient designs are elusive when it comes to overall costs. Water and other moderators slow down the bouncing neutrons to cause or give a better chance of them striking the nuclear fuel pellets inside the fuel rods that makeup fuel assemblies. The more strikes the better as they cause more heating due to the reactions (fission). Without a moderator, neutrons move to fast to be effective.

Heat exchangers are vulnerable points as high temperatures meet cold temperatures during heat transfer usually through relatively thin metal tubes. (Not so recently, San Onofe i.e. Original heat exchanges were meant to last the life of the plant’s operation, were recently replaced due to wear and the replacements are failing after only a few years.)

The more efficient a design, the less daughter by-products would remain, meaning any reactions would give off their heat at once leaving little or no nuclear byproducts...like a perpetual motion machine, ain’t going to happen.


48 posted on 02/11/2012 2:38:37 PM PST by Razzz42
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To: MCH
it's pretty impressive that PBR can be used to generate nuclear power!

More like natural gas.

49 posted on 02/11/2012 2:40:40 PM PST by hinckley buzzard
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To: SnuffaBolshevik
"So a large quantity of diesel fuel or a big pile of coal would work pretty well? How about boron?"

Most often used materials are simply things like paraffin wax and various C-H polymers (polyethylene,polypropylene). Cheap, easy to obtain, easy to fabricate and many other advantages. A layer of that covered by some lead (to soak up the resulting X and gamma radiation), and you're good.

Boron you don't want around at all.....it soaks up neutrons like a sponge and will stop your chain reaction dead in it's tracks. For that reason it is used on control rods, and as the "control of last resort".....flooding the reactor with water loaded with sodium borate.

50 posted on 02/11/2012 4:28:35 PM PST by Wonder Warthog
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To: EEGator

Maybe he is, maybe he isn’t. Either way, the future of Nuclear is LENR.


51 posted on 02/11/2012 5:26:14 PM PST by Kevmo (If you can define a man by the depravity of his enemies, Rick Santorum must be a noble soul indeed.)
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To: Kevmo

I hope you’re right.


52 posted on 02/11/2012 5:36:39 PM PST by EEGator
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To: Pontiac
"That means that this fuel is pretty close to bomb grade fuel"

And that is still light years away from being a usable weapons charge... not only in material processing, but there are many other factors involved...
"Almost" pure pellets are completely useless in a bomb and it would take untold amounts of resources to convert them. Few nations have the money and expertise to do it, let alone an individual or small group.

53 posted on 02/11/2012 7:38:15 PM PST by FunkyZero (... I've got a Grand Piano to prop up my mortal remains)
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To: Razzz42
If you expose a recent spent fuel assembly to air, heat from decaying material reactions will cause it to catch on fire in 15 minutes or less releasing its radioactive contamination. Takes five to ten years for the fuel assembly’s decay reactions to diminish enough to even think about exposing it to air and still you need circulating air to carry off residual heating.

Hmmm. I had one out a few months ago for about an hour and a half, it had just been running in the core for a few months a couple of days earlier. No overheating, no fire. The exposure rate was a few R/hr at the distance we were inspecting it, but otherwise it was fine.

54 posted on 02/11/2012 7:47:19 PM PST by chimera
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To: FunkyZero
Irradiated material is essentially useless in any case unless you have plutonium bred in a specially-designed breeding cycle. Then you've got the separation problem. Unirradiated HEU is a different story. If you could get enough of it of sufficient purity, the consensus among non-proliferation experts is that an inexperienced national program might come up with a relatively inefficient, low-yield weapon. An independent group working alone would likely not be able to do it.
55 posted on 02/11/2012 7:52:34 PM PST by chimera
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To: Lx

Those solar thermal plants are monstrosities in terms of land use, and while they are always quoted at their installed capacity, the best you’re going to do is about 40% capacity factor, and even that is somewhat variable. Modern grid control just isn’t set up to deal with significant generating assets coming on and dropping off in unpredictable and capricious manners. Believe me, it is a power dispatcher’s worst nightmare, trying to juggle variable sources in a time of high demand.


56 posted on 02/11/2012 8:00:05 PM PST by chimera
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To: chimera

Must not have been a spent fuel rod huh?

You can handle an new and unused fuel rod safely with your bare hands if you like.


57 posted on 02/11/2012 11:54:30 PM PST by Razzz42
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To: Wonder Warthog

http://resosol.org/InfoNuc/seismes/Japon2011/Nucleonics%20Week-20110324.pdf


58 posted on 02/12/2012 12:17:59 AM PST by Razzz42
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To: FunkyZero
"Almost" pure pellets are completely useless in a bomb and it would take untold amounts of resources to convert them. Few nations have the money and expertise to do it, let alone an individual or small group.

I think you over estimate what it would take to revert Uranium Oxide ceramic pellets back to Uranium metal.

It should be no problem for a bright high school chemistry student with some stainless steel drums and commonly available industrial chemicals.

If this was irradiated fuel that would be another story.

59 posted on 02/12/2012 3:29:16 AM PST by Pontiac (The welfare state must fail because it is contrary to human nature and diminishes the human spirit.)
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To: Razzz42

And the point of your link is precisely what??


60 posted on 02/12/2012 5:02:12 AM PST by Wonder Warthog
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