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PostPosted: Jan 10, 2014 10:47 pm 
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Eino wrote:
"Freeze it into a glacier."

Glaciers are not static. Glaciers are rivers of ice. How far will this glacier move in 60 years?
Some glaciers are ice rivers, some are ice lakes. The ice lakes are stable. I specified a stable glacier. This stable glacier will move nowhere in 60 years, by definition.

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PostPosted: Jan 11, 2014 6:06 pm 
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OK - It's your glacier. You do the permitting.

About the three loops. Can the middle loop be relatively stagnant and still get good heat transfer? Here's what I'm thinking. There will be a large tall tank. It will be filled with FliBe. Piping will enter the base. Hot FliBe will circulate through serpentine piping at the base of this tank. Heat will be given off to the FliBe in this tank which is cooler, but still hot. At the top of this tank will be another serpentine loop. This one will need to steadily increase in size from beginning to end. Water (condensate) will enter this loop. As it travels through, it picks up heat. It leaves as superheated steam.

The tank will serve two functions. It will serve as a heat transfer medium and as a shielding medium. There will be adequate distance from the bottom of the tank to the top of the tank to shield the water from the radioactive FliBe at the base. Of the three requirements to help with ALARA, time, distance and shielding, it will have distance and shielding.

A small recirc pump may be needed to take FliBe from the top of the tank where it is cooled by the water and recirc it to the base of the tank to aid in keeping the tank at uniform temperature. This may not be necessary if the FliBe cooled by the water can sink and be reheated as it naturally circulates.

The tank will be heavily insulated for heat loss. In the event of a reactor scram or normal reactor shutdown, the molten salt in the large tank will retain heat and will be able to power the turbine for some time before becoming too cool. If the molten salt in this tank freezes, it will be thawed upon a reactor restart. As it will take some time to heat up the large volume of molten salt in the tank, it may be some time before the turbine is back online. Instrumentation will be needed to detect if there are leaks from the primary FliBe loop into the tank (secondary loop) and into the tertiary water loop. Instrumentation will also be needed for tank level, temperature, temperature of each loop and flow through all loops. The exterior of the tank will need to be checked for leaks as well.

Here's a video that's kind of neat. It shows molten salt is conductive in the liquid state, but not in the solid form.

https://www.youtube.com/watch?v=ePzEVPDyJV8

I would think FliBe would act the same way. Leak detectors should be pretty simple for molten FliBe.

If the FliBe in the tank is kept hot and minimum steam is sent to the turbine, I'd think the unit could be a pretty good peaker.

OK, now tell me where I'm thinking wrong.


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PostPosted: Jan 16, 2014 10:31 pm 
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Getting back to the repowering concept, if you have cheap small cores, you could repower old coal plants, but if the nuclear island is anything other than cheap, the risks and overall life cycle costs would make an all new plant a much better bet.


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PostPosted: Jan 17, 2014 5:00 pm 
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"if the nuclear island is anything other than cheap" Is anything about a nuclear plant ever cheap? How cheap does it have to be? I'd guess a large new gas plant would be 3-4 hundred million. That's just a guess. A large new coal plant is over a billion.

How about a bid of two hundred million for a 100 Megawatt re-powered coal plant? This is in 2014 dollars.

This assumes that this is not the first one off the line. They've built a couple out in the Idaho desert and fixed design problems. Some poor souls have worked hard to get a generic Safety Analysis Report approved by government bureaucrats. A complete Probabilistic Reliability Analysis (PRA) has been done. It has been determined that an extremely abbreviated emergency plan is needed. Only local law officials and first off responders need be trained. The Security needs have been blessed off to be minimal. Spent fuel can be stored on site for the full expected life of the retrofit. The Federal government has determined that these units are safe. The generic license has been issued. The intervenors have had their say at the meetings for the first one and have been silenced by court order to stop disrupting projects such as this which have been determined to be in the public good. A generic design is available that can meet the requirements. Domestic suppliers are now available to meet your needs.

Your fuel costs will go down to zip. You will be able to keep a lot of your existing infrastructure. Your Distributed Control System will be reprogrammed to run the reactor. Operators will be retrained to get Senior Reactor Licenses to operate the new heat source. There will be a small hard panel to shut down the reactor in the event of DCS troubles. The turbine will be completely overhauled. Due to this reactor being safer than existing types we are legally able to build it closer than 40 miles to a major metropolitan center. Spent fuel can be stored at the site for the anticipated sixty year life of the retrofit. Demolition of existing site infrastructure, i.e. boiler, precipitators, etc. is not in the contract. There will be a clean interface to the turbine and the switchyard. Existing electric supplies from the switchyard and generator can be adapted to supply the reactor auxiliaries.

You will be able to run this thing and make money 365 days a year and 24 hours a day. Major outages will be every 2 years to overhaul the turbines, pumps, etc. Unlike the coal plant it replaced, there will be less dust, noise, train traffic, barge traffic,etc. This facility takes less land than the coal plant did. This land has been used to make a public fishing pier, a senior citizens center, a youth center and a monument to Glenn T. Seaborg.

What's the lead time on delivery? Hmmmm - 30 years.


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PostPosted: Jan 17, 2014 7:18 pm 
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'My suggestion is to take it to a stable glacier somewhere and freeze it into the glacier. There it can stay locked away from the biosphere for 120+ years till it decays away.'
Glaciers are a bit of a hot topic at the moment. New Zealand's largest is rapidly turning into a lake, and the giant Pine Island Glacier flowing out of eastern Antarctica has just been measured to be accelerating as it melts from underneath. If the Japanese heavily salt their tritiated water and ship it to a downwelling of the thermohaline circulation it should mostly sink out of sight for long enough to keep everybody happy.


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PostPosted: Jan 17, 2014 7:43 pm 
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jon wrote:
'My suggestion is to take it to a stable glacier somewhere and freeze it into the glacier. There it can stay locked away from the biosphere for 120+ years till it decays away.'
Glaciers are a bit of a hot topic at the moment. New Zealand's largest is rapidly turning into a lake, and the giant Pine Island Glacier flowing out of eastern Antarctica has just been measured to be accelerating as it melts from underneath. If the Japanese heavily salt their tritiated water and ship it to a downwelling of the thermohaline circulation it should mostly sink out of sight for long enough to keep everybody happy.
That was my old suggestion. The great ocean conveyor is about a 300 year cycle so there would be about a 4000 X reduction. But the deeps are not really a-biotic, so I switched to stable glaciers that basically are.

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PostPosted: Jan 27, 2017 4:45 am 
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Axil wrote:
I have advocated and lobbied for a bare bones Lftr core whose interface to the old coal fired plant generator is precisely matched through the use of a molten salt interface comprised as follows: Sodium Nitrate NaNO3 60 % Potassium Nitrate KNO3 40 %. This salt mix can support a maximum salt temperature of 550C.

All the components of the old coal fired power plant are maintained except the coal fired boilers. There are two molten salt storage tanks provided, a cold tank and a hot tank, see diagram below. The cold tank provides the input molten salt feed into the Lftr; the hot tank stores the heat output interface of the Lftr. The coal fired boilers are replaced by a steam generator located inside the hot molten salt tank, see the diagram below.

[Refer back to page 1 for image]

Water runs through the piping of the steam generator that converts the water to super heated steam compatible with the exact temperature and flow rate specifications required by the existing turboelectric generator sets that were supported by the old coal fired boiler house.

The molten salt interface provides the flexibility to match the heat flow rate, pressure, and temperature specifications of the existing coal fired plants generator sets. The hot molten salt storage tank receives either hot salt from the Lftr or cold salt from the cold salt tank to moderate the temperature of the super heated steam fed to the turboelectric generators

This approach will be the most attractive and economic repowering of existing coal fired coal facilities. There are a large number of these brand new plants recently placed in service throughout the world which have cost billions to construct. The utilities and governments who have made this large investment will look to recapture as much of it as possible.

The cost of such and molten salt/Lftr approach for a large coal fired plant repowering will be less then $100 million; this is far less the any CCS retrofit cost.


Can I come back to this topic, now that we have workable designs for MSRs, which are targetting a steam temperature of 600C.

The steam turbines sold for current nuclear plants are low temperature variants, so when looking for steam turbines we look at the supercritical ones designed for coal plants.

Is it feasible to retroft a MSR to a coal plant?

Are there newish coal plants that can be shut down? Coal plants are closing in the UK, but I'm not sure if the steam turbines are modern and new enough. The Netherlands and Germany have some brand new coal plants (http://www.climatechangenews.com/2016/1 ... -in-value/) , and in the Netherlands at least they recognise this is not a long term solution. It could be that in the UK, by the time MSRs are available, the coal plants and their turbines will have demolished.

[Edit]:https://en.wikipedia.org/wiki/Drax_power_station
Quote:
Between 2007 and 2012 the high and low pressure turbines were replaced by Siemens in a £100 million programme

If that covers 4GW - that is a very, very low price.

Though some components do get moved - this got "salvaged" from Didcot power station:
http://www.dailymail.co.uk/news/article ... -4mph.html
Does it make sense to move second hand steam turbines?

If a typical steam turbine is 750MW, would it make sense to attach three - for the sake of argument, Thorcon - units?

I'm trying to evaluate future cost trends in UK nuclear, from Hinkley C at £92.50/MWh (2012 prices), down via AP1000, Hualong Ones, and on to MSRs. What would be the cost benefit of retrofitting?

Moltex's cost study claimed $1000/KW capex for the nuclear island, and $1,000 for the steam island, plus site specific costs. With the site specific costs and the steam island taken care of, that should be a halving of capital costs.

Coming back to the Netherlands as an example, would it be nice to retrofit this place?:
http://www.rwe.com/web/cms/en/1772148/r ... wer-plant/
(Thorcon guys: Drool over that harbour! - Bring the nuclear island in on a barge and couple up! )


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PostPosted: Jan 27, 2017 5:42 am 
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I am a great votary of floating nuclear islands myself. However, the idea may be feasible only where 'the rest of plant' is within convenient piping distance for nuclear steam. Otherwise, you may need another float holding it nearby.
A more suitable idea for replacement of coal plants is leaching out more heat generating Cs and Sr from used fuel and use it as fuel in boilers/steam generators which can be placed underground and buried in nuclear concrete. It will last for decades as these isotopes have a half life of 30 yrs. When the power goes down, add a fresh unit for supercharging the steam.


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PostPosted: Jan 27, 2017 11:32 am 
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We had a 400,000 ton tanker laid up in Eemshaven in the early 1980's.
It's an excellent little harbour,
and would be perfect for ThorConIsle.

But reusing the existing TG is more trouble than its worth.

Definitely reuse the switchyard. But it is not a big swinger.


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PostPosted: Jan 27, 2017 4:16 pm 
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I found a proposal to build a six hundred kiloton Gravity Base Platform with two APR-1400s on it.
But floating plants have numerous issues of their own.


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PostPosted: Jan 27, 2017 5:59 pm 
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The ThorConIsle is a gravity base platform.


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PostPosted: Jun 04, 2017 12:59 am 
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There are a number of USC coal fired plants in many parts of the world that would make worthy conversion targets for MSR repowering, the key issue as stated above is the age of those plants when MSR's become available. China has some of the newest, that might be a very nice turn of events.


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PostPosted: Jun 07, 2017 12:53 am 
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The most convenient solution may be to remove old plant, compact it and bury it in a corner, and put up a standard design of nuclear plant.
You may also bury the existing plant in a slurry of its ash, which is bound to be considerable, and build the nuclear plant on a raft over it.


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PostPosted: Jun 07, 2017 9:03 pm 
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Isn't the ash usually acceptable for use in concrete though? Could you literally recycle the ash on-site during your build?


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PostPosted: Jun 08, 2017 2:46 am 
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Asteroza wrote:
Isn't the ash usually acceptable for use in concrete though? Could you literally recycle the ash on-site during your build?
The ash is actually not too bad as a uranium ore. Perhaps it could be extracted and consumed as a secondary fuel in a LFTR.

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