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Topic Title: ITER construction site update (Compared with my thoughts on a Molten Salt Reactor Building)
Topic Summary: ITER elevated platform site requiring an area of only 60 football fields
Created On: 02 January 2014 06:33 PM
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 02 January 2014 06:33 PM
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jarathoon

Posts: 1033
Joined: 05 September 2004

If you think the power density in the Wylfa Magnox nuclear reactor isn't enough for a modern engineer to be bothered with or get out of bed for, remember it will take until 2027 for the ITER fusion reactor to reach this level (around 1 MW/m3) for a few seconds at a time to start with and then at least another 30 years to double or triple this (to around 2 or 3 MW/m3 with around a 20% up rate in reactor dimensions I think)

You can either hear from the ITER DG Osama Motojima

"ITER DG Osama Motojima: Today fusion energy is an achievable goal"

http://www.youtube.com/watch?v=3K0Sa1jNgzk

or go on a more entertaining "ITER Construction Site Tour" with Julie Marcillat

http://www.youtube.com/watch?v=H3ZNoYFzEFU

The ITER elevated platform site requires an area of only 60 football fields apparently.

Compare the pictures you see on the tour with a cylindrical Generation IV fission molten salt reactor building, above ground with the size and shape of the old Dragon reactor building at Winfrith. A 33 metre diameter, a height of up 25 metres, and a depth into the ground of up to 15 metres. A reactor building containing up to four 900MWt molten salt reactors (3600 MWt ), along with a turbine hall building, cooling towers etc all fitting into one Association Football pitch.

I am not sure about the power density of the molten salt reactor yet, as I am not the one designing it. Somewhere in the range 30 to 75 MW/m3 seems achievable I think.

As is standard with chemical plants the reactor building root will lift, perhaps even be removable by crane. The reason why chemical plant buildings have lifting roofs is to stop the walls blowing out if there are sudden releases of pressure within the building (such as if a gas cylinder explodes inside the building). This is much less likely to happen with a molten salt reactor design, than a pressurized or boiling water reactor design; however if such a think did happen, in my view it would be better to keep the building side walls intact and release the pressure via the roof. The alternative is to expensively over-engineer the building to take a specfic loading pressure and then pretend that higher pressures above this limit will never happen. Actually this is gradually changing, with pressure relief systems being now installed. This just transfers the problem between a maxmium pressure limit and a maxiumum rate at which the pressure can rise in the building.

If the UK nuclear regulators require it, it may be possible to mount carbon filters in the roof structure. A lifting roof is not what the nuclear regulators are very used to, and so there may well be a debate needed between the ONR and the HSE (with experience of regulating the chemical industry) on this.
(Unfortunately DECC have now decided in their infinite wisdom to make the HSE and ONR separate organisations instead of being one. I have to say this clearly so people realise how bad a mistake this actually was, and how much this could potentially raise costs unnecessarily for private sector industries that want to increase the number of activities that cross the boundaries between the regulatory remits of these two organisations.)

The main strength in the molten salt building will be lower level structures up to the 5m working reactor floor level. All passive reactor cooling systems will be held safe below this level. Building structures above this will be designed to absorb the impact of say a large aircraft without compromising the lower level reactor containment, or the passive fission product decay heat removal systems or the larely passive volatile fission product off-gassing systems.

Either a new reactor building can be built in a 3 year timeframe or the old one repaired (depending on the level of damage).

Just a thought...It is certainly possible to have a test molten salt reactor running for 4 or 5 years ath the Wylfa Magnox site before, the first fusion energy from ITER dribbles out. It just requires some visionary leadership and a little cash as I previously explained in a different post.


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James Arathoon
 02 January 2014 06:39 PM
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jarathoon

Posts: 1033
Joined: 05 September 2004

Should read...

Actually this is gradually changing in the nuclear industry, with pressure relief systems being now installed on reactor containments. This just transfers the problem between a maxmium pressure limit and a maxiumum rate at which the pressure can rise in the building though.

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James Arathoon
 04 January 2014 02:53 PM
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davegray65

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When I looked at Osama Motojima on youtube I didn't hear him mention the IETR MW/m3 figures that you give in your message.

I believe that the area covered by the tour includes fuel production. Fuel production for existing and proposed nuclear stations is carried out offsite. Consequently to make a like for like comparison the volume of the IETR fuel production facilities should be excluded. There may other IETR facilities providing services that current and future nuclear sites receive from off site locations. It's not clear from you message whether you excluded these IETR facilities.

Regards


Dave Gray
 04 January 2014 11:50 PM
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jarathoon

Posts: 1033
Joined: 05 September 2004

Originally posted by: davegray65

When I looked at Osama Motojima on youtube I didn't hear him mention the IETR MW/m3 figures that you give in your message.



No he didn't mention this, although he did welcome criticism.
This was simply an order of magnitude calculation of mine

http://www-fusion-magnetique.cea.fr/gb/iter/iter02.htm

Assuming ITER Tokamak is toroidal in shape for the purtpose of this estimate
Major radius of plasma (R) = 6.21 m
Minor radius of plasma (r) = 2.0 m

Volume of a torus = (pi * r^2) * (2 * pi * R) = 490 cubic metres

Maximum power output = 500 MWt
Power Density = 1.0 MW/m3 (Roughly the same as a Magnox Nuclear Reactor)

(this is an overestimate of the power density as the actual plasma volume is 837 cubic metres )

Similar calculation possible for DEMO assuming that the above dimensions are scaled by 20% and a power output of 1800MWt say.

https://www.iter.org/construction/layout

The ITER site is enormous and includes lots of things like the Poloidal Field Coils Winding Facility, which presumably won't be used very often once ITER is built. This is one of 39 buildings that will be built of the ITER platform apparently.

http://www.iter.org/construction/pf

"The building's metal cladding - five layers of metal sheeting and insulation - will isolate the poloidal field coil work space, where cleanliness is a priority, from the dust of the platform."

Do the 6 poloidal field coils really have to be built under dust free conditions?
Do the 6 poloidal field coils really need such a large building to wind them in? Couldn't they have just built some racks to store the field coils at one end of the building once wound?
Does the Poloidal Field Coils Winding Facility just have one use?

On another page "Specialised Tooling"

http://www.iter.org/construction/assemblytooling

"The ITER bridge cranes can work together to lift loads of up to 1,500 tons [or tonnes?], or operate separately."

Once construction is complete they are going to be left with quite a lot of expensive kit on site that will rarely if ever get used again.

I am only pointing this sort of thing out because if engineers want to get involved with designing a molten salt reactor building and surrounding site infrastructure, they will have to be a little bit more cost conscious than the ITER engineers (actually a whole lot more cost conscious).

Another reason why I like to think about building a molten salt development reactor building with a strong yet light removable roof, is so that a used integral molten salt reactor can be replaced with a new one. Some sort of radiation shielding box would have to be lowered in with the roof removed. The roof could be replaced and the de-fuelled reactor lifted up into the shielding box using the internal crane. The building air is then filtered of any residual radioactivity before the building roof is again removed so that the shielded box can be craned out. A new replacement reactor can then be lowered in to replace it. The heavy lifting crane need only be hired for the few days that it is needed.

The idea will be to set form factor standards and other design standards for building inherently safe molten salt reactors (and other types of inherently safe small modular reactor in the range 100MWt to 900MWt), before the development reactor building design is finalised.

If this is done it may be possible to reuse the building at the end of the development process to house a new set of commercial nuclear reactors designed to generate electricity for the grid. The trick will be to look in detail at the labour intensive nuclear decommissioning work that is required for current nuclear plants that weren't designed to be quickly and easily dismantled (i.e. without creating lots of dust and procedures that might expose workers to large doses of radioactivity if they go wrong) and try to design this work away, so the building may be easily and quickly re-tasked cost effectively.


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James Arathoon
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