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PostPosted: Sep 29, 2014 6:07 am 
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Thanks Cyril.

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Mines are almost certainly not a problem.


So you think there will be enough natural uranium in mines to power all north America and Europe with ESBWRs for the 21 th century without requiring seawater uranium (sorry, this is going out of topic).

Quote:
sadly, that GE is not as firm in pushing ESBWR as say Westinghouse is in selling the AP1000. That's strange because, economically when it comes down to it ESBWR should have an advantage over AP1000 so GE should be in a very competitive position if they were more serious about new build.


Quote:
I have wondered about that too. Somehow, GE appears to be very lukewarm about nuclear energy and its GE-H nuclear division is treated as a stepchild.


GE have businesses in gas turbines, gas, oil, wind turbines, solar inverter, steam turbines for coal plants, ... An ESBWR will probably last 80 years so maybe nuclear energy is not so profitable for the company. They can sell the fuel but it is maybe not too profitable.


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PostPosted: Sep 29, 2014 7:06 am 
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Looks like the World Nuclear website has a good page on energy analysis of the nuclear lifecycle.

http://www.world-nuclear.org/info/Energ ... r-Systems/

The EROEI is only 74.

Some interesting differences that explain this. First off this is an older plant (Forsmark, more materials of construction) and the analysis is dated (2002, lots of diffusion enrichment still in the market).

Also the World Nuclear website appears to make the same error as Lenzen - all electrical inputs are tripled, even though electrical output is measured. That's a case of triple counting! If the analysis used thermal output of the plant then yes triple counting electrical inputs is accurate... but it doesn't.

Lets convert the World Nuclear table to a Forsmark "ESBWR equivalent" (that is multiply by 1.55 * (60/40) = 2.325, except for build/decom. is only factor 1.55). Then compare with my numbers behind that:


TYPE WORLDNUCLEAR CYRIL
Mining 12.8 PJ 7.8 PJ
Conversion 9.5 PJ 0.074 PJ (???)
Enrichment 53.7 PJ 2.1 PJ
Fuel fabrication 1.8 PJ 0.23 PJ
Plant operation 2.6 PJ 0 PJ
Build & decommission plant 6.4 PJ 1.6 PJ
Waste management 10 PJ. 0.5 PJ

TOTAL 96.8 PJ 11.8 PJ

This is rather amazing.

Mining and enrichment I can explain with the triple counting of electricity and diffusion plants.

Conversion is a big mystery. 9.5 PJ is not defensible from a process engineering check. My figure was 0.074 PJ. I can see how to get to 0.1 PJ with a monstrous amount of solvents consumed and not bothering to recycle the solvents, but that is getting silly already. Not sure what is going on here.

Then there's fuel fabrication - again can't justify this by looking at the processes.

Plant operation - how can one spend 2.6 PJ in operating the plant??? this is 60000 tonnes of diesel.

Waste management - 10 PJ, again very high. My number is less than 0.5 PJ for a massive dry cask facility.

This is very weird. It appears the World Nuclear figures are difficult to defend from a process engineering viewpoint, unless I've overlooked monstrous process energy steps in multiple key areas.

Help?


Last edited by Cyril R on Oct 03, 2014 7:50 am, edited 1 time in total.

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PostPosted: Sep 29, 2014 11:03 am 
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Next section: transporting the materials.

This one is a bit difficult because we don't know where the materials will come from.

We need to transport the following bulk materials over long distance:

13,000 tonnes U3O8.
95,000 tonnes iron ore.
68,000 tonnes steel/iron.
276,000 tonnes concrete. Actually this is mostly water, sand and gravel that will be sourced locally. But lets assume we haul the cement from a very distant source. That's 44,000 ton cement.

Lets assume all of this stuff must travel (the equivalent of) 10000 km by ship. That's exaggerated but lets use that to account for some intermodal transport delivery by truck or such.

So we need to transport 220,000 tonnes of bulk stuff 10000 km. 2,200,000,000 ton-km. Say it with me, two point two billion ton kilometers.

Run of the mill freight ship uses 0.2 MJ/ton-km. 440,000 GJ. We can probably do better than run of the mill, king size ocean freighter would do better.

Anyway. Energy needed to transport the stuff even over very long distance is many times smaller than the energy needed to mine, convert, refine the stuff. Good.


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PostPosted: Sep 29, 2014 11:06 am 
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Part VII v3. inputs vs outputs. Updated with transport fuel energy.

Construction of powerplant: 1,250,000 GJ + 250,000 GJ + 72,000 GJ = 1,572,000 GJ.
Construction of spent fuel dry cask storage and basemat: 450,000 GJ + 26,000 GJ = 476,000 GJ
Mining uranium: 7,800,000 GJ
Mining iron ore: 13,600 GJ (68 kton steel @ 0.2 GJ/ton)
Mining concrete: 55,200 GJ (276 kton @ 0.2 GJ/ton, assume same as iron ore which is very pessimistic)
Transporting all the material (see previous post): 440,000 GJ.
Conversion: 14,000 GJ + 40,000 GJ (HF, hydrogen in deconversion, recycling) + 20,000 GJ (electrolysis, F2, wild guess!!) = 74,000 GJ.
Enrichment: 2,073,600 GJ, 9.6 million SWU (according to Urenco includes infrastructure embodied energy).
Deconversion: 2,600 GJ (exothermic process, product H2 and HF counted in conversion).
Fuel fabrication: 1,800 GJ + 206,250 GJ + 23,100 GJ = 231,150 GJ.

Total input: 12,738,150 GJ

Electrical output: 1.55 GJ/s, 90% capacity factor, 60 years: 2,639,563,200 GJ.

Energy out vs energy in or EROEI: 207

We are still above 200!


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PostPosted: Sep 29, 2014 11:09 am 
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Any ERORI over 10 should be good enough. All nuclear power plants qualify.
Next problem is radioactive wastes. Some US states and European countries are apprehensive of nuclear power for this reason. There is no actual shortage of fuel but there is resistance to uranium mining at many places. A closed cycle involving breeding of fissile feed and using up most of uranium and preferably thorium too making the fuel practically inexhaustible is required to be the next step. All fast reactors and possibly thermal/reduced moderation reactors using thorium can be used as breeders. MSR or liquid fueled reactors are more neutron economic.
Graphite moderator is a major waste source.


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PostPosted: Sep 29, 2014 12:25 pm 
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jagdish wrote:
Any ERORI over 10 should be good enough. All nuclear power plants qualify.
Next problem is radioactive wastes. Some US states and European countries are apprehensive of nuclear power for this reason. There is no actual shortage of fuel but there is resistance to uranium mining at many places. A closed cycle involving breeding of fissile feed and using up most of uranium and preferably thorium too making the fuel practically inexhaustible is required to be the next step. All fast reactors and possibly thermal/reduced moderation reactors using thorium can be used as breeders. MSR or liquid fueled reactors are more neutron economic.
Graphite moderator is a major waste source.


Good, you managed to stay on topic for two whole (albeith short) sentences. You are clearly making progress.

It isn't correct though. EROEI of 10 is quite unacceptable if most of the input comes from fossil. If we have a world with say 10000 GWe of nuclear and you have 1000 GWth of fossil support for that, that is quite unacceptable in terms of particulate and greenhouse gas emissions. If half of the input comes from fossil it is still 500 GWth equivalent, also not acceptable long term.


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PostPosted: Sep 29, 2014 2:29 pm 
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Very interesting analysis. But I would be far more interested in the $$$ amounts instead.
Nuclear energy is massively efficient. Only the anti nuclear morons think otherwise.
But money makes the world go around.
It would be extremely interesting knowing an ESBWR costs US$ x/kWh in complete startup costs and another US$ y/kWh in total operational costs after start up.
Just an idea.

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PostPosted: Oct 03, 2014 11:30 am 
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The following extensive study from INL has a lot of data on the front end of the nuclear fuel cycle:

http://www.inl.gov/technicalpublication ... 731816.pdf

This work suggests the front end guzzles 1% the output of the plant. The centrifuge figure is spot on with mine, and the other figures seem quite reasonable.

The conversion figure seems monstrously large. According to the INL study, conversion guzzles 0.025 GJ of thermal input alone per MWh, 0.007 GJ per GJ electrical. 18,330,300 GJ. This is around 9 times the enrichment energy - for a chemical process!

Time to read up on this conversion thing.


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PostPosted: Oct 07, 2014 9:03 am 
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Ok, I sent an email to the World Nuclear Association about the article. In return and to my amazement I got a reply from none other than Mr. Ian Hore-Lacy, himself. Mr. Hore-Lacy kindly updated the article with new figures.

http://www.world-nuclear.org/info/Energ ... r-Systems/


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PostPosted: Jul 27, 2015 1:18 pm 
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Also reference to this:
After something Cyril said about using Inconel in the ESBWR to make the RPV lighter and allow potentially for higher pressures, I started looking into Inconel 718, however as far as I know there is no forging press available to forge Inconel that large.
So I decided to look up casting - as cast the UTS is 114ksi and the yield strength of 71ksi.

If we set the hoop stress at 25% UTS to allow for small irregularities in the casting then the wall thickness for the ESBWR (7.1m ID) comes out at 156mm.

Which is surprisingly thin.
It would weigh a few hundred tonnes of inconel but that is only a few million dollars (so a few $/kW) - but you would avoid forging and you would have an enormous corrosion margin as its Inconel all the way through.

You could cast the RPV in only two pieces - the lid and the main body.
Which eliminates all the weld inspections on the RPV itself.

Ideally it would be heat treated but I don't know where you can heat treat a 24m long, 7.5m outside diameter RPV main body in one piece.


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PostPosted: Jul 27, 2015 4:12 pm 
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Nickel alloys suffer radiation embrittlement if I am not mistaken.

Also we know that the current LWR vessels work well and we have the experience, you will have to significantly lower the price of the vessel if you want to take the risk of using Inconel.

Maybe a design like the Supercritical Water Reactor is worth the risk of trying a nickel vessel, if the vessel is sufficiently protected from the neutron flux.


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PostPosted: Jul 27, 2015 5:05 pm 
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Current LWR vessels are a major production bottleneck - they are expensive, require scarce industrial assets for their production and place a limit on the size of the pressure vessels available.
Which is why we haven't got HP-BWRs which would significantly improve efficiency.

A casting can be constructed to almost arbitrary sizes with the only limitation being that we have to be able to find a crane able to lift it into the reactor containment during construction.
As to radiation embrittlement I am not too sure - but remember that in the ESBWR only a very small of the RPV's 27m height is anywhere near the reactor - so we could always handle it by doubling the thickness of the casting in the core belt region. The outer material would be shielded from the core by the inner material.
We can also potentially, if we can find a larger crane, simply cast a thicker vessel to enable a 315 Celsius core.


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PostPosted: Jul 27, 2015 5:42 pm 
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Well I don't have the feeling that the american and french LWR programs were impeded by lack of vessels. The country must invest in a forge.

Concerning the embrittlement, the margins (imposed by the safety authorities) against brittle fracture are huge. We know we can handle it with ferritic steel, with nickel alloys I don't have enough knowledge but I guess other people on this forum know more about it.

For placing the neutron shield we must increase the diameter and so the thickness of the vessel. But if you say you can do any size and thickness by casting OK but you must remain a lot cheaper and simpler than current solutions.

Concerning the current methods it is possible to go further in size and thickness with the same materials, need a bigger forge.


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PostPosted: Jul 27, 2015 8:59 pm 
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fab wrote:
Well I don't have the feeling that the american and french LWR programs were impeded by lack of vessels. The country must invest in a forge.


France had a lot more heavy industry in the 70s and 80s when the programme was in full swing.
As did America.

And remember they were building dinky units - the average unit in the French programme is probably bigger than in the American programme - and even then most of the French units were only 900MWe PWRs - hardly big by modern standards.

I read at least one study that suggested that the time delay to get a new large forging plant will be at least seven to eight years after the decision to build - which is a long time in the current environment.
fab wrote:
For placing the neutron shield we must increase the diameter and so the thickness of the vessel. But if you say you can do any size and thickness by casting OK but you must remain a lot cheaper and simpler than current solutions.


I think it is really, casting these huge shapes is not particularly challenging, the only issues might be concerns with uneven cooling but I imagine that can be controlled by careful handling of the moulding and the quench procedure.
fab wrote:
Concerning the current methods it is possible to go further in size and thickness with the same materials, need a bigger forge.

The days of things like the Heavy Press programme are long gone unfortunately.


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PostPosted: Jul 27, 2015 11:15 pm 
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I've learned a lot more about the 718 in pressure vessel service recently. It hasn't been good to my idea in general.

Big issue with castings is fracture toughness, arguably more important even than tensile strength, for a pressure vessel. (increasing thickness can compensate for lower strength; poor fracture toughness is dangerous in any gauge in pressure vessel application).

Turns out inco 718 is not known to be all that great here and a little radiation at low temperatures makes it a good deal worse...

25% UTS is overconservative. ESBWR vessel thickness is 180 mm, corresponding to 2/3 of the YS of the low alloy steel employed (typically A5xx class). Codes typically require 2/3 yield or 1/2 UTS, whichever is smaller. For In718 it is tensile limited in the aged state, so you design for 50% of code minimum UTS at design pressure. We're probably looking at around 75 mm. Keep in mind that design pressure is typically some 125% of operating pressure, plus you always get stronger material than the minimum spec. So you get a lot more safety margin in reality.

Unfortunately some parts need to be thicker. Bottom vessel head has the geometric strength of cheese, with all those holes for control rods. So it'll be at least 50% thicker.

Economics of casting favor series production of large amounts of smaller casting, with complex shapes so simple welding and machining are difficult alternatives. Sadly it looks like ESBWR pressure vessels don't really comply with these favored requirements...

But the fracture toughness for cast 718 is going to be the main issue, it seems.

I think we can go for a quality forging for the bottom four pieces (petal, transition forging, and first two ring forgings). Rest can be welded plate. If you can do circumferential welds (forged rings) on 718 you can do axial welds (latter are easier in fact). With lower weight the forging is going to be easier. One attractive thing with 718 is that is very easy to work with (soft, high elongation) before the final heat treatment. So forging is going to be a piece of a cake for the 718 vessel. The forgings are largish but not so large as to be very difficult to put in a large industrial oven for the ageing heat treatment.

Quote:
Concerning the embrittlement, the margins (imposed by the safety authorities) against brittle fracture are huge.


That's correct, and in my opinion rightly so. Its "ductile vessel or no vessel". I'm much less in favor of the large safety margins to yield strength if the material is already very ductile (it will just deform slightly, so what). Its surprising how much you have to wrinkle and dent a soda can before it develops a tear. And when it does you'll notice it is just a small tear in one of the dent folds. And the 6000 class alloys used for soda cans are not even the most ductile alloys in fact.

Quote:
We know we can handle it with ferritic steel


Actually many ferritic alloys are between moderate toughness and terrible, the thing that is really tough about them is the welding difficulty (which is not a good thing, either). They are tricky and unforgiving in thermal treatments and welding. They require a lot of post weld annealing done just right. They are also prone to radiation embrittlement that then promotes cracks in tensile stress even when all the correct forging and welding and annealing have been done (PWRs have this issue with their higher vessel fluence than BWRs).


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