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PostPosted: Apr 23, 2014 3:40 pm 
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E Ireland wrote:
Putting it there is likely to expose the hydrocarbons to massive gamma flux.

Which means it will turn to char and hydrogen gas.


The idea was to put sufficient water between the containment boundary and the fuel tanks.

That works in normal operation, but I maintain that storing large amounts of synfuels from a synfuel production reactor in the same building or hull the reactor is in, is just bad design. It isn't necessary and has no advantage, only risks. Leaks could result in the char and hydrogen gas you mention. Leaks would mean the heat sink and tons and tons of flammable liquids are mixed. Any fire is in a difficult area where we really don't want bad things going on (the emergency heat sink and shielding).


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PostPosted: Apr 23, 2014 4:05 pm 
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Cyril R wrote:
Quote:
Hydrocarbons are used for cooling and lubrication in all kinds of places.


Yes, and they have routinely caught fire in almost every single one of these applications. However, the amounts of oil in cooling systems and lubrication is small and the flash points are high, making the risk manageable... nothing like, say, storing a day's worth of low flash point gasoline production from nuclear synfuel plant, next to the nuclear plant itself!


I understand your point but I don't agree with it. I'm not going to try to convince you of the safety of using hydrocarbons to cool nuclear reactors since I am not an expert on the topic, many aspects of this are subjective, and you are not the person that needs convincing.

I will say that from an engineering standpoint this sounds like an interesting solution with its own interesting problems. This may come to fruition at some point, and just might give a nice light show for spectators on the beach.

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PostPosted: Apr 23, 2014 4:23 pm 
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Apart from safety, the heat transfer performance of hydrocarbons is very poor compared to water. And, the temperatures are practically limited by the dissociation and gumming up rate of the coolant. The radiolysis is a very serious problem resulting in short coolant shelf life. Water radiolysis is easy to recombine again, unlike hydrocarbons. Hydrocarbon cooled reactors make large volumes of irradiated coolant waste over their lifetime. Plus coking of hydrocarbon on coolant channels is a serious issue for long term operation. So, no big gain to be had.

Hydrocarbon coolants were tried. We keep getting back to water for its publicly underappreciated advantages. Molten salts may challenge this rule of water, in the long run.

There is virtually no work being done right now on hydrocarbon cooled reactors, so its pretty much academic anyway.


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PostPosted: Apr 24, 2014 12:07 am 
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Cyril R wrote:
E Ireland wrote:
Putting it there is likely to expose the hydrocarbons to massive gamma flux.

Which means it will turn to char and hydrogen gas.


The idea was to put sufficient water between the containment boundary and the fuel tanks.

That works in normal operation, but I maintain that storing large amounts of synfuels from a synfuel production reactor in the same building or hull the reactor is in, is just bad design. It isn't necessary and has no advantage, only risks. Leaks could result in the char and hydrogen gas you mention. Leaks would mean the heat sink and tons and tons of flammable liquids are mixed. Any fire is in a difficult area where we really don't want bad things going on (the emergency heat sink and shielding).


Yeah, I probably should have made it clearer I meant an outer concentric fuel storage tank cylinder surrounding the secondary coolant tank which surrounds the containment vessel, but the water tank bottom boundary is to the sea, based on the concept art in the MIT article. Either that, or an FPSO style long hull with the stern area being a cube water tank surrounding a reactor, all the way at the back.

Though considering that an undersea HVDC line would be nominally installed to the power block from shore, coinstalling a subsea fuel pipeline would make more sense if your synfuel market was close by and avoids the local storage issue. Otherwise, you will need storage on board to hold between shuttle tanker runs, though one could cheat and put the tankage within a large concrete gravity block anchor so the storage isn't in the floater hull proper.

A full FPSO style hull with storage can serve three basic markets, near shore mooring but beyond the 12 mile limit with HVDC electricity and synfuel export, in port docking with direct export of synfuel and power (disaster relief?), and full offshore (military seabase/seabasing logistics center) with mainly synfuel production. As an initial customer/demo, the full offshore capability potentially being funded by the US Navy covers many things, including bypassing NRC licensing.


But, most FPSO's are designed to run from bad storms by dropping their mooring turret. A spar buoy or TLP will have to ride out the waves and face serious motion. DCNS' fully submerged powerplant avoids the weather wave issues almost completely.

Here's the current page for the DCNS plant called Flexblue, though to be fair it was also a make-work program for their french submarine shipyards. Of note, their concept uses a semisub ship for delivery and features a horizontal layout, making installation easier (no heavy lift crane)(if well designed, the whole system is on a skid which can be slipped into the tube before the endcap is welded on). If one were willing to let stuff go solid and could tolerate a 90 degree change when cold, one could do a vertical layout which would be amenable to a MSR with freeze plug dump tankage.


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PostPosted: Apr 28, 2014 10:12 am 
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Asteroza wrote:
Here's the current page for the DCNS plant called Flexblue, though to be fair it was also a make-work program for their french submarine shipyards. Of note, their concept uses a semisub ship for delivery and features a horizontal layout, making installation easier (no heavy lift crane)(if well designed, the whole system is on a skid which can be slipped into the tube before the endcap is welded on). If one were willing to let stuff go solid and could tolerate a 90 degree change when cold, one could do a vertical layout which would be amenable to a MSR with freeze plug dump tankage.


The Flexblue concept by DCNS (French naval shipyards) was presented a couple of years ago. It is a logical proposal if you are in the shipbuilding industry and also do something with nuclear energy on the side, as DCNS does. I have found a couple of slides from 2013, outlining their concept a little further (see attachment), but I really question the feasibility of it, building submarine-like structures, more than 100 metres long, to house a reactor and the power conversion system. Refuelling such a reactor seems to be a rather cumbersome operation.


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PostPosted: Apr 28, 2014 2:15 pm 
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camiel wrote:
Asteroza wrote:
Here's the current page for the DCNS plant called Flexblue, though to be fair it was also a make-work program for their french submarine shipyards. Of note, their concept uses a semisub ship for delivery and features a horizontal layout, making installation easier (no heavy lift crane)(if well designed, the whole system is on a skid which can be slipped into the tube before the endcap is welded on). If one were willing to let stuff go solid and could tolerate a 90 degree change when cold, one could do a vertical layout which would be amenable to a MSR with freeze plug dump tankage.


The Flexblue concept by DCNS (French naval shipyards) was presented a couple of years ago. It is a logical proposal if you are in the shipbuilding industry and also do something with nuclear energy on the side, as DCNS does. I have found a couple of slides from 2013, outlining their concept a little further (see attachment), but I really question the feasibility of it, building submarine-like structures, more than 100 metres long, to house a reactor and the power conversion system. Refuelling such a reactor seems to be a rather cumbersome operation.


No more cumbersome than refueling a nuclear submarine I imagine. Though that is significantly more cumbersome than refueling a civilian power plant to be sure. In some markets this is just about the only way you'll get new nuclear capacity in a reasonable time frame (e.g. coastal California).


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PostPosted: May 05, 2014 12:09 am 
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How long before the people on the west of Pacific (Russia, China, Japan or even S.Korea) lease one to LA? Its construction can not even be approved by the NRC!


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PostPosted: May 05, 2014 3:40 pm 
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Good night! You are talking about building a GW power transmission line across the pacific?!??!!

Maybe build one in Mexico, and send the power to San Diego - but then an ocean based transmission line is reasonable alternative to land based transmission lines if the public resistance to land based is too high.


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PostPosted: May 05, 2014 4:04 pm 
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Lars wrote:
Good night! You are talking about building a GW power transmission line across the pacific?!??!!


I read that as a proposal for a foreign built nuclear power plant being floated into a harbor or, at a maximum, floated out to international waters. The term "international waters" can mean several things depending on treaties and such, could be as much as 200 miles. That's still a long way but it has been done.

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PostPosted: May 05, 2014 7:59 pm 
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Well HVDC cable laying technology and transmission distance is evolving to the point where soon it might not be entirely ridiculous to suggest that the UK should obtain electricity from the Churchill Falls hydroelectric project operated by NF&Labrador Hydro.


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PostPosted: May 08, 2014 2:44 am 
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Cthorm wrote:
camiel wrote:
Asteroza wrote:
Here's the current page for the DCNS plant called Flexblue, though to be fair it was also a make-work program for their french submarine shipyards. Of note, their concept uses a semisub ship for delivery and features a horizontal layout, making installation easier (no heavy lift crane)(if well designed, the whole system is on a skid which can be slipped into the tube before the endcap is welded on). If one were willing to let stuff go solid and could tolerate a 90 degree change when cold, one could do a vertical layout which would be amenable to a MSR with freeze plug dump tankage.


The Flexblue concept by DCNS (French naval shipyards) was presented a couple of years ago. It is a logical proposal if you are in the shipbuilding industry and also do something with nuclear energy on the side, as DCNS does. I have found a couple of slides from 2013, outlining their concept a little further (see attachment), but I really question the feasibility of it, building submarine-like structures, more than 100 metres long, to house a reactor and the power conversion system. Refuelling such a reactor seems to be a rather cumbersome operation.


No more cumbersome than refueling a nuclear submarine I imagine. Though that is significantly more cumbersome than refueling a civilian power plant to be sure. In some markets this is just about the only way you'll get new nuclear capacity in a reasonable time frame (e.g. coastal California).


Like I said, if the full system is on a skid platform and you can pop off the endcap, replacement of internals is much easier than a military nuclear submarine, that usually has to cut out a dorsal patch of hull to yank the reactor. Additionally, with meltable fuels, there is also the opportunity to simply pump our fluids out smaller hatches if you don't need to take the entire reactor+power conversion system skid out.


As for really long distance HVDC, there have been semi-serious proposals for the european supergrid/DESERTEC and a pacific rim supergrid extending from Australia to Japan through SE asia.


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PostPosted: May 09, 2014 1:52 am 
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Lars wrote:
Good night! You are talking about building a GW power transmission line across the pacific?!??!!

Maybe build one in Mexico, and send the power to San Diego - but then an ocean based transmission line is reasonable alternative to land based transmission lines if the public resistance to land based is too high.

I meant built in Asia and sailed over to LA on lease. It could be anchored just outside the terretorial waters to avoid cumbersome regulations. Only power is sold to US utilities who could alternatively hold it in international waters on lease.


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PostPosted: May 09, 2014 11:06 am 
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If the regulators aren't happy with your power plant they will simply refuse to allow your power cable to enter US waters. I don't think much has changed as far as the regulators go. However, it is more difficult to get public opinion riled up against something that is far out to sea such that there is no evacuation discussions, no neighborhood notifications, etc. so in that sense it would help.


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PostPosted: May 13, 2014 12:45 am 
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Russians are already into floating power plants.
http://en.wikipedia.org/wiki/Russian_fl ... er_station
The US had one stationed at Panama Canal
The Chinese may buy one for study and start own building.


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PostPosted: Jul 07, 2014 7:19 pm 
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http://oilprice.com/Alternative-Energy/ ... IMBYs.html
Another view on floating nuclear power plants.


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