# Energy From Thorium Discussion Forum

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 Post subject: Re: APWR Steam Cycle efficiencyPosted: Jul 30, 2015 3:19 pm

Joined: Jun 19, 2013 11:49 am
Posts: 1546
As far as I know there are no problems with pushing to such low tails fractions - its just more enrichment.
A typical break-even price for new enrichment capacity is widely considered to be \$45/SWU, rather than the current price of \$70.

This reduces the price of the \$660/kgU raw material case to only \$5267/kg of enriched fuel (tails fraction of only 0.045%).
That is an increase of \$3180/kg compared to the baseline case, which is only \$7.57/MWh over the baseline case.

Breeder reactors are looking ever more shake-y.

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 Post subject: Re: APWR Steam Cycle efficiencyPosted: Jul 30, 2015 3:53 pm

Joined: Sep 22, 2013 2:27 pm
Posts: 262
The Point "Increasing condenser vacuum is possible but extraordinarily expensive" is a bit strange.

As a mechanical engineer I would calculate a vacuum in the condensor of 0,1 MPa. It doesn`t matter if it is 0,095 or 0,097.

In Germany the rhine river has a cooling water temperature from 4°C in winter up to 23°C (this July up to 26°C). The North sea has a temperature of 5°C in winter and up to 18°C in summer (close to the coast). The condensor pressures range between 28mbar in winter up to 54mbar in summer.

If you take the cooling water from the sea you have to consider tides, flows that might differ in different seasons and foulings in the pipes. The worst situations are if the pipe is blocked by vegetation or you suck in the warm cooling water. I would recommend simple steel pipes.

Beside of the cooling water temperature it is the surface Dimension of the condensor, the material (titanium, stainless steel) and its heat conductivity and the flow velocity makes up the vacuum in the turbine.

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 Post subject: Re: APWR Steam Cycle efficiencyPosted: Aug 02, 2015 6:18 pm

Joined: Jun 19, 2013 11:49 am
Posts: 1546
Rather peripheral but I was bored so I decided to run the reference core DMSR fuel cycle cost.

It comes out at 4890MWh/kg of 20% enriched uranium. (Assuming the thorium has negligible cost, which it does, since even at current U/SWU prices it comes out at \$7.90/g)
That is roughly \$1.62/MWh.

In the \$660/kgU 'price-cap' scenario it comes out at \$25,580/kg.
Which translates as the sky high price of \$5.23/MWh.

These prices are without a re-enrichment credit, which could cut the cost by something like 40% over a long timescale.

I think that kills breeders right there really.

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 Post subject: Re: APWR Steam Cycle efficiencyPosted: Aug 03, 2015 5:59 am

Joined: Sep 02, 2009 10:24 am
Posts: 511
Just to clarify, you are saying?:
- with current Uranium ore prices, a reference-DMSR reactor has a fuel cost of \$1.62/MWh
- with Uranium from sea water, the fuel cost rises to \$5.23/MWh

For comparison, EDF have been offered a guaranteed price of £92.50/MWh (=\$145) for the first EPR.

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 Post subject: Re: APWR Steam Cycle efficiencyPosted: Aug 03, 2015 6:14 am

Joined: Sep 02, 2009 10:24 am
Posts: 511
alexterrell wrote:
Quote:
Increasing condenser vacuum is possible but extraordinarily expensive.

OK. 15 tons per second dropping 5-10m is a power source of 750-1500 KW, minus inefficiencies.. Pretty small for a 500MW-1GW plant. However, there are turbines specifically designed for this kind of low head, so 500-1000KW could be recovered. An extra 0.1%.

On the subject of cooler water, I read in the planning document for sizewell C (2xEPR):
Quote:
Cooling water infrastructure would be installed from the power station to offshore, with intake structures installed at a distance of approximately 3km from the shore, and outfall structures installed between 0.8 and 3km from the shore. The outfall and intake structures would be connected to the station by horizontal tunnels below the sea bed. These would be installed through the use of tunnel boring machinery rather than cut and fill. Flood defence and coastal protection measures would also be installed from the foreshore for the power station.

So it seems part of the cost is to actually dig a subway sized tunnel 3km out to sea?

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 Post subject: Re: APWR Steam Cycle efficiencyPosted: Aug 03, 2015 12:10 pm

Joined: Jun 19, 2013 11:49 am
Posts: 1546
alexterrell wrote:
Just to clarify, you are saying?:
- with current Uranium ore prices, a reference-DMSR reactor has a fuel cost of \$1.62/MWh
- with Uranium from sea water, the fuel cost rises to \$5.23/MWh

Yes, this is what I am saying - and this price is likely to drop if we allow re-enrichment.

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 Post subject: Re: APWR Steam Cycle efficiencyPosted: Aug 24, 2015 3:51 pm

Joined: Sep 22, 2013 2:27 pm
Posts: 262
Dear Alex,

if you need about 100m3/s for cooling an EPR and have a flow velocity of 1 m/s you will need a large pipe.

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