Which of the following reactors are economically viable/passively safe

[mesa]

Which of the following types of nuclear power generation and/or advances should we invest the most time into that provides cost effective (competitive) power production with the highest safety?

"Fast reactors. Supercritical water reactors. Reduced moderation reactors. Powdered fuel. Solid thorium oxide fuel. Replacement of Zirconium cladding with SiC"

 

[Astronuc]

Which of the following types of nuclear power generation and/or advances should we invest the most time into that provides cost effective (competitive) power production with the highest safety?

"Fast reactors. Supercritical water reactors. Reduced moderation reactors. Powdered fuel. Solid thorium oxide fuel. Replacement of Zirconium cladding with SiC"

The efficacy or cost effectiveness of any of those concepts has yet to be demonstrated. Research of SiC is being conducted in a variety of institutions, but the challenge will be to realize the high reliability of Zr-alloy cladding (used in LWRs), particularly from the standpoint of the sealing the ends of the tube. The holy-grail of nuclear fuel is 'accident tolerant' fuel which can function reliably under normal and accident conditions. However the economics of such fuel may be challenging, if realizable at all.

SCWRs have very challenging conditions from the standpoint of the resistance to materials to corrosion and degradation.

 

[mesa]

The efficacy or cost effectiveness of any of those concepts has yet to be demonstrated. Research of SiC is being conducted in a variety of institutions, but the challenge will be to realize the high reliability of Zr-alloy cladding (used in LWRs), particularly from the standpoint of the sealing the ends of the tube.

I have been reading about the replacement of zirconium alloys for cladding with SiC, the benefits and economics seem very reasonable on paper.

SCWRs have very challenging conditions from the standpoint of the resistance to materials to corrosion and degradation.

It's good that they have the ability for breeding and high efficiency, one pass cooling is also a plus. I recently learned there have been fossil fuel plants employing supercritcal systems so there is some real world data on this type of system (granted minus the neutron radiation).

The holy-grail of nuclear fuel is 'accident tolerant' fuel which can function reliably under normal and accident conditions. However the economics of such fuel may be challenging, if realizable at all.

I think if we want to convince the general public that nuclear power is 'safe' this has to happen, but as you said economics is key as well.

 

[Astronuc]

It's good that they have the ability for breeding and high efficiency, one pass cooling is also a plus. I recently learned there have been fossil fuel plants employing supercritcal systems so there is some real world data on this type of system (granted minus the neutron radiation).

The gamma/neutron radiation is the critical environmental factor. Corrosion rates increase by a factor of 3 or more, or even an order of magnitude, and material microstructural changes occur. While the fuel may be incore for 4 to 6 years, the core internals must ideally make it 40 to 60 years. Key factors are the replacement of large capital structures and the disposal of irradiated material.

 

[mesa]

The gamma/neutron radiation is the critical environmental factor. Corrosion rates increase by a factor of 3 or more, or even an order of magnitude, and material microstructural changes occur. While the fuel may be incore for 4 to 6 years, the core internals must ideally make it 40 to 60 years. Key factors are the replacement of large capital structures and the disposal of irradiated material.

Radiation will no doubt be a major issue. Do you (or anyone else) have information on the performance and corrosive effects of SCW with fossil fueled plants?

 

[Astronuc]

Radiation will no doubt be a major issue. Do you (or anyone else) have information on the performance and corrosive effects of SCW with fossil fueled plants?

There is a lot of work published in journals and available from varies labs.

For example - http://www.kns.org/jknsfile/v40/JK0400147.pdf
CORROSION BEHAVIOR OF AUSTENITIC AND FERRITIC STEELS IN SUPERCRITICAL WATER

"The corrosion mechanism of the steels in SCW is likely to be the reaction/diffusion controlling mechanism, while the oxide spallation may be caused by the growth stress." Electrochemical potential and radolysis are also factors, as is the change in microstructure of the oxides and alloys due to radiation.

There is a lot of work published by ORNL on corrosion and behavior of austenitic and ferritic stainless steels.

Corrosion of Candidate Materials for Supercritical Water-Cooled Reactors
http://iweb.tms.org/NM/environdegXII/1397.pdf

http://books.google.com/books?id=HiHyITZbcqoC&pg=PR7&lpg=PR7&dq=Supercritical+water+corrosion,+ferritic+stainless+steels&source=bl&ots=-5h7TlF_vA&sig=HO754iwzqfoLve4Vvcula0vdB28&hl=en&sa=X&ei=g5geUryPEMm0sQTw-oHYBw&ved=0CFkQ6AEwBw#v=onepage&q=Supercritical%20water%20corrosion%2C%20ferritic%20stainless%20steels&f=false

 

[nikkkom]

Which of the following types of nuclear power generation and/or advances should we invest the most time into that provides cost effective (competitive) power production with the highest safety?

The most cost-effective short-term thing (read: cheap) would be to use current LWR and HWR designs with only incremental improvements, but it's short sighted.

I personally would like to see development of closed fuel cycle(s) with breeding (either Uranium or Thorium, or both) and reprocessing. Which way is economically best (fast uranium reactors, heavy water uranium reactors, thorium cycle) is yet to be determined...

Note that "incremental improvements" to date *are* inching into the breeding territory - PWR's neutron spectrum is not completely thermal, burnup (-> production and consumption of Pu) steadily increases, MOX fuel has been developed.

Sometimes incremental improvements are better than huge leaps into unknown: if you are wrong and this new thing isn't working as well as hoped, it's easier to go back and try something else.

 

[mesa]

The most cost-effective short-term thing (read: cheap) would be to use current LWR and HWR designs with only incremental improvements, but it's short sighted.

I agree.

I personally would like to see development of closed fuel cycle(s) with breeding (either Uranium or Thorium, or both) and reprocessing. Which way is economically best (fast uranium reactors, heavy water uranium reactors, thorium cycle) is yet to be determined...

Yes and at some point there will be a need to build test reactors.

Note that "incremental improvements" to date *are* inching into the breeding territory - PWR's neutron spectrum is not completely thermal, burnup (-> production and consumption of Pu) steadily increases, MOX fuel has been developed.

Sometimes incremental improvements are better than huge leaps into unknown: if you are wrong and this new thing isn't working as well as hoped, it's easier to go back and try something else.

So where do you think we should start?

 

[nikkkom]

So where do you think we should start?

I am not qualified enough to be sure about this. There are a lot of specialized knowledge involved in this area, which I don't have.

Here is my not-sufficiently-informed opinion:

(1) Fast lead(-bismuth?) reactors.
Pros: non-flammable coolant, atmospheric pressure operation, high temperatures (better generation efficiency), operational reactors of this type exist today.
Cons: reportedly, breeding coefficient is only marginally better than 1.

(2) Reduced moderation light water reactors.
Pros: natural extension of existing PWR technology.
Cons: it is unclear that breeding (coeff > 1) is achievable.

(3) Heavy water breeders
Pros: natural extension of CANDU technology.

(4) MSR
Pros: non-flammable coolant, atmospheric pressure operation, high temperatures (better generation efficiency)
Cons: need to develop online reprocessing

 

[mesa]

I am not qualified enough to be sure about this. There are a lot of specialized knowledge involved in this area, which I don't have.

Here is my not-sufficiently-informed opinion:

(1) Fast lead(-bismuth?) reactors.
Pros: non-flammable coolant, atmospheric pressure operation, high temperatures (better generation efficiency), operational reactors of this type exist today.
Cons: reportedly, breeding coefficient is only marginally better than 1.

(2) Reduced moderation light water reactors.
Pros: natural extension of existing PWR technology.
Cons: it is unclear that breeding (coeff > 1) is achievable.

(3) Heavy water breeders
Pros: natural extension of CANDU technology.

(4) MSR
Pros: non-flammable coolant, atmospheric pressure operation, high temperatures (better generation efficiency)
Cons: need to develop online reprocessing

Aside from astronuc's densely knowledgeable posts I found yours to be the most insightful even though we find each other frustrating at times.

Lead cooling looks good, now we know where Rusty Holden worked out his own ideas for a design of thorium breeder MSR.

 

[etudiant]

Aside from astronuc's densely knowledgeable posts I found yours to be the most insightful even though we find each other frustrating at times.

Lead cooling looks good, now we know where Rusty Holden worked out his own ideas for a design of thorium breeder MSR.

Afaik, the Russians used Lead/bismuth eutectics as a coolant in some of the sub reactors.
They gave up that approach because the hot metal was too corrosive.
So it would be needing some serious research to become suitable for a commercial reactor.

Apart from the higher capital costs involved, it seems the CANDU design is a good starting point for a next generation reactor. Can be easily refueled while running and quite tolerant of a range of fuels, so should be able to address much of the required parameters. Yet the capability is languishing with minimal life support. Makes one doubt that the nuclear revival has much substance.

 

[African Rover]

The Russians are building an SMR, Lead Bismuth reactor for commercial use. It is supposed to go into operation in 2017/2020
http://www.world-nuclear-news.org/NN_Heavy_metal_power_reactor_slated_for_2017_2303122.html

They are also operating Sodium cooled reactors for 27 (?) years. The BN type of reactor. The drivers of nuclear technology in the future will be Russia, China, India and some other emerging countries.