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 Post subject: Re: High Pressure BWR
PostPosted: Aug 22, 2014 7:33 am 
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jon wrote:
Any thoughts on the Lightbridge type helical cruciform metal fuel for BWRs? The surface area would be much greater, and the central temperature lower.


Yes, any fuel that is good enough for PWR will work with BWR because fuel conditions are less nasty.

Again though the question is how far you can push power density in a natural circulation design. Could be that less restrictive orificing gets you a lot but I don't know the design space available (anyone have information on the orificing plate in ESBWR?). The ESBWR vessel is already too tall for my tastes, at 27+ meters. Making it taller to get more driving force isn't attractive.

For forced circulation BWRs the sky is the limit basically. It seems especially suitable for Kerena (formerly SWR1000) because that 'only' generates 1250 MWe or so and it is forced circulation yet it has shorter lower pressure drop core like the ESBWR.


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 Post subject: Re: High Pressure BWR
PostPosted: Aug 25, 2014 4:53 am 
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What if you added this non-electrical pump (http://www.fisonic.us) to the BWR to enhance flow without electricity, no moving parts, and only 4 main parts: 1) T shell, 2) Venturi nozzle for mixing, 3) compression nozzle, 4) divergent nozzle, if additional pressure head is needed? Although I have to say that this pump would work better on a low pressure BWR to enhance flow.


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 Post subject: Re: High Pressure BWR
PostPosted: Aug 25, 2014 7:58 am 
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Ed P wrote:
What if you added this non-electrical pump (http://www.fisonic.us) to the BWR to enhance flow without electricity, no moving parts, and only 4 main parts: 1) T shell, 2) Venturi nozzle for mixing, 3) compression nozzle, 4) divergent nozzle, if additional pressure head is needed? Although I have to say that this pump would work better on a low pressure BWR to enhance flow.


This appears to be a typical steam injector or ejector or eductor or whatever it is called. Is the idea here to inject live steam from the turbine bleed system into an injector? This could be very interesting as the steam pipe could be routed from the top so no bottom penetrations, and no moving parts means high reliability.

The question I have is what is the workable range of pressure, temperature and will it work on nearly saturated water or does it need subcooled water? Lindsay may be able to answer these questions.

There are also issues with certain transients where the steam lines are isolated. Then you have no steam for the injector which I think might be a problem in certain ATWS scenarios.


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 Post subject: Re: High Pressure BWR
PostPosted: Aug 29, 2014 11:51 pm 
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Any expert ideas on adding a salt like BeF2 to water to make it a higher temperature reactor at lower pressure? Might help in a PWR.


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 15, 2017 3:19 pm 
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Revisiting this on the basis of information I gained later.

With a Prestressed Cast Iron Vessel you could build a pressure vessel to almost arbitrary sizes and pressures.
And with this TiAlN/AlN coating it would be possible to deal with the increased cladding temperatures of high steam conditions.

360C 185atm would seem to be achievable.


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 18, 2017 4:07 pm 
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Higher pressure without higher temperature probably doesn't buy all that much efficiency improvement.

Probably you can do pretty well with a marginal improvement in BWR conditions, maybe 8 MPa saturated steam conditions. Probably pushing 40% efficiency with optimized large turbine.

Really should push for a SiC-SiC fuel clad for next gen BWRs.


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 18, 2017 4:46 pm 
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Well 185atm with a second reheat would enable the intermediate pressure turbine to have normal BWR live steam conditions at the inlet (285C 75atm)

Which probably gains you significant efficiency gains, remember that we would be talking about 360C steam, not 285C.


Also trying to work out if you can use austempered ductile iron (GRADE 1600 ADI has a compressive strength of 2500MPa... triple GG25 grey cast iron used in most PCIV calculations) to make a ridiculously thin prestressed reactor containment that can still withstand aircraft impacts - then large amounts of heat might be able to simply conduct out of the containment building passively.
And the relatively small size of existing furnaces might not matter too much with the relatively thin sheet castings.


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 19, 2017 9:12 am 
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What kind of efficiency do you think you can get with those steam conditions?

What's the fracture toughness and impact energy of the austempered ductile iron?


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 19, 2017 9:46 am 
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Cyril R wrote:
What kind of efficiency do you think you can get with those steam conditions?


I think pushing 40% is not out of the question, although I would have to do the calculations, but based on simple isentropic analysis of the state points [what is the isentropic efficiency of a modern steam turbine?] it looks very promising.
Cyril R wrote:
What's the fracture toughness and impact energy of the austempered ductile iron?


Varies with grades according to this chart I found on the internet.
The stronger in compression grades are less tough, but even the weakest grade would still be so much stronger than concrete that it almost doesn't matter - the vessels thickness for pressure vessel containment will still be very thin (on order of a few inches).

Resistance to aircraft strikes is the important factor.
Varies from 44MPa/(m^0.5) to 100+

The big problem is the cast iron is only being held together by the prestressing and relatively weak keying on the blocks - so it cant be treated as a big mass like concrete can. But even the keys might allow aggregate tensile strength comparable to the concrete.

EDIT:

The AP1000 Shield building cylindrical section is only 36" thick and is supposed to protect the steel vessel from aircraft impacts. Althoguh the steel content has apparently been redacted.


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 20, 2017 10:07 am 
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Exceeding 40% efficiency is a big plus for a LWR. Even psychologically. BWR with the efficiency of a SCWR but none of the materials problems.

Keying should be able to achieve nearly the same strength as homogeneous material, if properly designed. Think Lego blocks. They are very strong except in the direction of the keys. Large aircraft crash is a horizontal or shallow angle affair so vertical keys should be pretty good, esp. if the keys are thick.

Not familiar enough with the alloy suggested to know it's potential. Has it been used before in a commercial app? I think you may be better off with a commercial material. For the containment there are various high tensile strength polymers that are of interest. They don't corrode and have much higher strength than most metals. Dyneema is an example. Not too good at high temperatures, of course.

The containment building suffers from prestress in terms of aircraft crash. That's because it is external loading and the prestress is for internal loading. This is actually a big downside when it comes to prestressed containments - external events esp. aircraft crash are much more damaging. The prestress basically acts as additional load on top of the aircraft crash load. Steel fiber concrete matrix, reinforced concrete, possibly steel plate type, is probably your best defence against aircraft crash. Or berming/undergrounding.


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 20, 2017 11:11 am 
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Cyril R wrote:
Exceeding 40% efficiency is a big plus for a LWR. Even psychologically. BWR with the efficiency of a SCWR but none of the materials problems.

It also significantly reduces cooling water demand after all, at 33% efficient you have two units of waste heat per unit electric, but at 40% that falls to 1.5 units.
Cyril R wrote:
Keying should be able to achieve nearly the same strength as homogeneous material, if properly designed. Think Lego blocks. They are very strong except in the direction of the keys. Large aircraft crash is a horizontal or shallow angle affair so vertical keys should be pretty good, esp. if the keys are thick.

That is potentially very interesting, and potentially allows for a surprisingly thin, and thus light, containment.
Cyril R wrote:
Not familiar enough with the alloy suggested to know it's potential. Has it been used before in a commercial app? I think you may be better off with a commercial material. For the containment there are various high tensile strength polymers that are of interest. They don't corrode and have much higher strength than most metals. Dyneema is an example. Not too good at high temperatures, of course.


Austempered Ductile Iron is used in a variety of applications for automotive components [including axles for very heavy military lorries made by Oskosh] and similar, however there is a limit in that the largest austempering furnace I know of only has room for ~10t castings.
Which obviously puts a limit on us in that it would start to take a much larger number of castings than it would with regular ductile iron, where castings can be made as large as can be practically moved to the site (record is a couple of hundred tonnes I believe).

My primary interest is in building out of a high thermal conductivity material so heat can be lost passively in an accident, and if necessary (and all on site pumps and ducting has failed) the simple expedient of having the fire brigade play hoses on the containment dome can help disperse heat more rapidly.
Cyril R wrote:
The containment building suffers from prestress in terms of aircraft crash. That's because it is external loading and the prestress is for internal loading. This is actually a big downside when it comes to prestressed containments - external events esp. aircraft crash are much more damaging. The prestress basically acts as additional load on top of the aircraft crash load. Steel fiber concrete matrix, reinforced concrete, possibly steel plate type, is probably your best defence against aircraft crash. Or berming/undergrounding.


It appears so, I have been pondering ice-type condenser containments simply because they allow you to build a smaller and more compact containment building that is not only harder to hit properly (more of the mass of the plane will miss a small containment) but also allows less material to be used to reach your strength requirements, which saves foundation mass and number of crane lifts in the construction schedule.

But ideally I owuld like a ductile iron/steel containment which would lose 0.1% or more of the power of the reactor through teh walls when the interior is only at ~100C.
Ice in the containment will melt into water that will help thermally couple the reactor vessel to the containment in a LOCA/Blackout combination accident.
And the ice itself will soak up enough heat that by the time it reaches ~100C and the pressure starts to climb again the reactor heta rate will have dropped low enough to allow the whole thing to reach a (relatively) cool equilibrium.


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 25, 2017 7:42 am 
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Biphenyl or similar low vapor pressure moderator-coolant could be used to transfer more heat at lower pressure. Small wastageages could be managed like engine oil in IC engines. The coolant could be topped up at refuelling times.


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 27, 2017 5:30 pm 
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Jim L. wrote:
Would annular fuel pellet/fuel rods also help with uprating the BWR? I think that flow and heat transfer would be improved while also keeping the centerline fuel temps down.
Try the star design metalic fuel from Lightbridge.

Disclosure statement: I bought a bit of LightBridge stock on a lark.

_________________
DRJ : Engineer - NAVSEA : (Retired)


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 29, 2017 5:16 pm 
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KitemanSA wrote:
Jim L. wrote:
Would annular fuel pellet/fuel rods also help with uprating the BWR? I think that flow and heat transfer would be improved while also keeping the centerline fuel temps down.
Try the star design metalic fuel from Lightbridge.

Disclosure statement: I bought a bit of LightBridge stock on a lark.


The stock is doing pretty poorly. Aren't they making any progress by now?


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 Post subject: Re: High Pressure BWR
PostPosted: Jul 31, 2017 6:49 pm 
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It appears Siemelkamp had an outline for the design of a ~1350MWe BWR vessel in the 70s built out of prestressed cast iron.
It was 7750mm inner diameter and similar height to an ESBWR vessel - however very interestingly it had an outer diameter of only 8880mm.
That means an average wall thickness of ~565mm
Which is much more than the ~180mm thickness of the forged vessel in the actual ESBWR, however it has a larger diameter (supporting another power uprate perhaps?) and is only ~770mm wider than the ESBWR vessel, and includes insulation which the forged vessel does not.

Makes me wonder if it might not be possible to fit such a vessel into a plant without changing the rest of the plant.

With wire winding and a heavy lift crane you could even lift it inot the plant in one piece if you wanted with no prestressing gallery required.

Might be able to match the APWRs 1700MWe nominal output with the extra diameter....


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