Energy From Thorium Discussion Forum

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PostPosted: Feb 12, 2018 11:20 am 
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Canada is part of the Generation IV consortium. Its main nuclear lab, CNL (former AECL), is focusing on developing a supercritical water reactor which uses pressure tubes (1200MWe in power), building upon its experience and its familiarity with CANDUs.

The CNL Nuclear Review dedicated a whole issue (winter 2016) to this specific topic:

http://pubs.cnl.ca/toc/cnr/5/2

It seems an interesting concept, also because it intends to use a Pu-Th-U233 fuel cycle in the future, but I wonder about its viability and how such a pressure tube SCWR stacks up against the SCWR with a regular RPV, considering the high pressure involved (>25 MPa) and temperatures (>600 degrees C).

Any thoughts on this ?


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PostPosted: Feb 12, 2018 8:17 pm 
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The solution to high pressure problem is a low vapor pressure coolant. The moderation could be left to exotic heavy water.
The coolant could be a molten salt, carefully balancing between neutron economy and cost. Stable hydrocarbon could also be selected.
A bigger tank of an economical coolant could act as a heat store and cover load following to an extent.


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PostPosted: Feb 13, 2018 12:24 pm 
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I've been very interested in the PT-SCWR for a long time.

The high efficiency pressure tubes (where the load bearing segment is in thermal contact with the calandria and not the coolant) they propose are far more likely to be practical, in my opinion, than the enormous pressure vessels that pressure vessel SCWRs would require.
Indeed I am not convinced a forged SCWR pressure vessel is even possible, I think prestressed vessels would be required.


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PostPosted: Feb 14, 2018 12:11 am 
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The reaction space, either the vessel or tubes have a high radioactivity and temperature. It would be best to move the high pressure of steam or supercritical water to generation area like the steam generator. The initial heat transfer should best be at a manageable pressure.


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PostPosted: Feb 20, 2018 4:38 pm 
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E Ireland wrote:
I've been very interested in the PT-SCWR for a long time.

The high efficiency pressure tubes (where the load bearing segment is in thermal contact with the calandria and not the coolant) they propose are far more likely to be practical, in my opinion, than the enormous pressure vessels that pressure vessel SCWRs would require.
Indeed I am not convinced a forged SCWR pressure vessel is even possible, I think prestressed vessels would be required.


Agreed on internal insulation & cool calandria water. Many of the issues with CANDU PTs are temperature related: most simply disappear altogether by reducing the operating temperature. It is generally good engineering practise to get the pressure retaining parts of anything as close to room temperature as possible.

PV SCWR seems quite feasible; JSW has indicated they can make about 600 tonnes forgings, which is about twice the weight of typical (US design) proposed SCWR PV's. Though they are limited in the # of forgings a year they can produce.

Still, prestressed is certainly an option too. Taking the concept of internal insulation and extending it to the vessel (where insulation and a cooled liner do the job) makes sense.


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