Next Nukes – cooperation for cheaper energy

[Barry Brook]

A new post has been published on BraveNewClimate. Link here:
bravenewclimate.com/next-nukes

As the debate over climate policy picks up again in the wake of Hurricane Sandy and President Obama’s reelection, policymakers should prioritize efforts that will accelerate the adoption of zero-carbon technologies, especially the only proven baseload source available: next generation nuclear. But how to best achieve this?

This BNC Discussion Forum thread is for the comments related to this BNC post.

[gallopingcamel]

Thanks for sharing your views at Desmogblog.

While I don't comment much on BNC since Barry cast me into the outer darkness I still read every post and support Barry's "Solutions" even though replacing fossil fuel electricity generation with nuclear will have no measurable effect on the climate.

Take a look at this: energy.llnl.gov/informatics.php

In the USA electrical generation accounts for only ~30% of the fossil fuels consumed. Even if you eliminate all of it there won't be a noticeable effect on climate.

I am working on a post based on a week long visit to a BWR in South Carolina. A couple of things struck me very forcibly. First the huge head count......1,450 people to produce 1.8 GW peak! Second, in spite of the huge head count the cost of producing electricity is much lower than I expected.

[jagdish]

Of the essentials of the gen IV, I am most convinced about pyroprocessing and least about sodium coolant.
Electrolytic separation of plutonium and other transuranics is good as it gives fissile feed to the fast reactor without bothering for any more 'Purity' than required for the purpose. Sufficient conversion/ breeding ratio can be obtained for high burn up.
Sodium fires have been a recurrent problems in many countries the latest victim being Japan. Russia, India and China continue to work with it manfully even though the Russians have a second string, lead, in their coolant bow.
I think that lead eutectics and salt coolants must continue to be developed simultaneously till a satisfactory solution is developed.

[David B. Benson]

jagdish --- The EBR-II ran for 30 years without problems.

[Roger Clifton]

Jagdish @ 20130104 1626 implies that sodium coolant is unsatisfactory, presenting recurrent problems. But weren't these mainly popularity problems among the fearful?

May I suggest that a sodium fire does not present any technical problem? Instead, by moving to less-proven coolants, the industry would be making a tactical error -- appeasing ignorant people who have been made frightened of sodium fires.

Appeasement is the reason the nuclear industry has saddled itself with an excessively tight target of 2 mSv/a for its own special version of smoke. When it is breached, the original fears re-emerge, the public panics and leaders overreact.

The alternative to appeasement (at least, that I can see) is education. An effective education program requires national leaders to talk the talk. An international agreement on an emergency response to carbon pollution might yet make that happen. In the meantime the technology needs to be readied for the emergency roll-out.

[cyrilr]

Apart from popularity issues, I do believe that molten lead has a number of real (physical, engineering) advantages over sodium.

1. Higher boiling point, and lack of negative void coefficient, means voiding is not going to happen even in beyond design basis events.
2. Less tight coolant channels can be engineered because of lead's lower absorption and other nuclear characteristics. This means that even though lead is heavier, pump power (pressure drop across the core) can be reduced.
3. The spectrum can be faster (if needed) since lead has a lower neutron lethargy than sodium.
4. 2/3 higher volumetric heat capacity as sodium
5. Less extreme thermal conductivity reduces thermal shock in transients.
6. In the event of core damage, lead's higher density provides fuel dispersal over compaction, ruling out re-criticality in beyond design basis events.
7. Lead's compatibility with air and water avoids the need for expensive engineered components, ranging from fast sodium isolation systems, to double walled (expensive!) steam generators. The intermediate loop can also be avoided, further reducing equipment and pump power costs. It also means that flow blockage from sodium oxide contaminant is avoided. Things like loss of cover gas systems become inconsequential.
8. Lead shields gamma radiation very well and has much lower equilibrium activation than sodium. Sodium24's activity rivals that of the fission products at equilibrium (!).

[jagdish]

The fact remains that setbacks to fast reactors have been mainly due to sodium fires. Even if it has been managed by Russia, India and China who are still continuing with sodium cooled fast reactor development, safer coolants are possible and desirable. Sodium has an advantage of being benign to metallic containment. It is still worthwhile to develop corrosion protection against lead or salts and be safe against fires which are difficult to handle in the highly radioactive environment inside the reactors.

[cyrilr]

Jan 4, 2013 2:00:31 GMT 9.5 gallopingcamel said:

Thanks for sharing your views at Desmogblog.

While I don't comment much on BNC since Barry cast me into the outer darkness I still read every post and support Barry's "Solutions" even though replacing fossil fuel electricity generation with nuclear will have no measurable effect on the climate.

Take a look at this: energy.llnl.gov/informatics.php

In the USA electrical generation accounts for only ~30% of the fossil fuels consumed. Even if you eliminate all of it there won't be a noticeable effect on climate.

Electric generators are just the start. Once you have covered electricity, it becomes attractive to electrify transport via electric vehicles and trains, and electrify low temperature heating via heat pumps. That takes up a sizeable chunk of CO2 emissions. Next is industrial heat and reduction of metal ores such as iron oxide. This can be electrified, all that is needed is cheap electricity to make the economics work. Coal for making iron is tough to beat in price, but possible. Coal for iron will probably one of the last bastions of fossil fuels we will tear down.

[Roger Clifton]

CyrilR - that is a marvellous list of properties for the use of lead coolant. I might add one more, and that is that the tenfold higher density implies higher buoyancy forces, a useful consideration for ensuring passive convection.

Assuming the two liquids expand with temperature at a similar rate (sodium solid expands at 70 um/m/K, while lead solid expands at 30 um/m/K, which is a crude guide to the thermal expansion of the liquids), the high contrast in density implies that the buoyancy of hot lead is maybe five times the buoyancy of hot sodium.

The fact that the liquid column is still ten times heavier means that the liquid lead won't be flowing as fast as sodium, but it will certainly have a greater momentum, scouring any hot pockets of lazy liquid in the core structure.

[edireland]

I am not convinced we really need liquid metal cooled reactors to reach our objective.

We can now apparently reach above unity breeding ratios with Boiling Water Reactors (atleast Hitachi claims we can, see RBWR) using Uranium oxide fuel. With uranium nitride fuel we can apparently reach breeding ratios of 1.12 which would be more than enough for our needs.

More to the point we can build BWRs relatively inexpensively en masse now, we are not in the experimental phase as we are with the other designs.

[cyrilr]

Jan 15, 2013 18:14:21 GMT 9.5 edireland said:

I am not convinced we really need liquid metal cooled reactors to reach our objective.

We can now apparently reach above unity breeding ratios with Boiling Water Reactors (atleast Hitachi claims we can, see RBWR) using Uranium oxide fuel. With uranium nitride fuel we can apparently reach breeding ratios of 1.12 which would be more than enough for our needs.

More to the point we can build BWRs relatively inexpensively en masse now, we are not in the experimental phase as we are with the other designs.

That's an interesting idea, just use a tighter pitch on the BWR to get a faster spectrum. Use existing BWR technology. Though it is still a faster spectrum reactor, and that changes the licensing basis a bit (especially with regards to recriticality post accidents).

Lead does have some advantages and disadvantages over this fast BWR idea:

- With the lead fast reactor, there are two loops rather than 1 and one loop is liquid metal, the other steam. That complicates the design compared to a fast BWR.
- With the lead fast reactor, the primary loop is not radioactive, non-pressurized, does not contain hydrogen and is inert in accidents compared to steam (no oxidation of metals, etc.). That's a serious safety advantage. The steam side safety systems of the BWR could still be used, such as isolation condenser systems, and these would be much easier than with a BWR, because it's a clean steam loop with no radioactivity and no noncondensables such as hydrogen to clog the isolation condensers as happened at Fukushima Daiichi unit 1.

Plus the higher temperature means a lower cost per watt, higher efficiency steam loop.

[Douglas Wise]

Cyril,

I'm becoming increasingly concerned that, while we all take pleasure in airing our views on optimum nuclear technology, years go by without any sign of a large scale nuclear renaissance.

For those who are not seriously alarmed by adverse anthropogenic effects upon climate, leisurely debate might seem the most likely route to an optimum energy policy. However, most climate scientists seem to be coming to the conclusion that we are well past the point where we can hope to stabilise temperatures with a mere 2 degree C rise and that we'll now have trouble staying below a rise of 4 degree C, even if we start taking mitigation very seriously and very quickly ( www.bristol.ac.uk/cabot/events/2012/194.html ). If these experts are correct, we need to roll out nuclear reactor designs that are already licensed at a rate far faster than has ever happened before. We probably ought also to deploy S-PRISM plus the accompanying reprocessing technology as fast as possible in the interests of sustainability and economics, given that it is the only near term option for breeding. This will require strong government action to facilitate financing and a telescoping of current regulatory processes.

This is not to deny that molten salt cooled or lead cooled reactors and molten salt fuelled and cooled reactors might not prove superior in a few decades. Instead, I'm attempting to suggest that there are good reasons to go into panic/war footing mode if we hope to prevent a civilisation crash within 4 decades.

[edireland]

Jan 16, 2013 0:23:02 GMT 9.5 cyrilr said:

Jan 15, 2013 18:14:21 GMT 9.5 edireland said:

I am not convinced we really need liquid metal cooled reactors to reach our objective.

We can now apparently reach above unity breeding ratios with Boiling Water Reactors (atleast Hitachi claims we can, see RBWR) using Uranium oxide fuel. With uranium nitride fuel we can apparently reach breeding ratios of 1.12 which would be more than enough for our needs.

More to the point we can build BWRs relatively inexpensively en masse now, we are not in the experimental phase as we are with the other designs.

That's an interesting idea, just use a tighter pitch on the BWR to get a faster spectrum. Use existing BWR technology. Though it is still a faster spectrum reactor, and that changes the licensing basis a bit (especially with regards to recriticality post accidents).

Lead does have some advantages and disadvantages over this fast BWR idea:

- With the lead fast reactor, there are two loops rather than 1 and one loop is liquid metal, the other steam. That complicates the design compared to a fast BWR.
- With the lead fast reactor, the primary loop is not radioactive, non-pressurized, does not contain hydrogen and is inert in accidents compared to steam (no oxidation of metals, etc.). That's a serious safety advantage. The steam side safety systems of the BWR could still be used, such as isolation condenser systems, and these would be much easier than with a BWR, because it's a clean steam loop with no radioactivity and no noncondensables such as hydrogen to clog the isolation condensers as happened at Fukushima Daiichi unit 1.

Plus the higher temperature means a lower cost per watt, higher efficiency steam loop.

I do worry about lead cooled reactors, they have a whole host of rather annoying problems.

1. You have to do on load refueling and maintenance of the reactor core becomes rather troublesome because unlike a LWR you cannot simply cool it off to room temperature, take the top off and physically look inside, using fresh water pumped into the reactor vessel to shield the operators from residual radiation.
Even with Sodium you can let the reactor cool down to near room temperature without too much difficulty, which means equipment has to be able to tolerate far less extreme environments for procedures such as refueling.

2. The mass of lead has me worried, when you are dealing with a liquid that is an order of magnitude heavier than water all sorts of structural problems become apparent.
The mass of the coolant in the core suddenly becomes non trivial which means your cooling loops have to be far stronger than otherwise.

3. The hydrogen in the isolation condensors issue at Fukushima would be dealt with in newer reactors through containment venting (which would draw the gas through the isolation condensor into the primary containment) and by the installation of platinoid based recombination catalysts at various locations in the reactor and containment building.
Those should cause the hydrogen and oxygen to recombine into steam in a controlled manner and prevent the conditions for a gas explosion from developing.

There is also a major advantage in the RBWR concept as it seems feasible to refit an existing ABWR or ESBWR into an RBWR during a refueling outage at some point in the future without replacing massive components of the reactor or its containment structure.

This would seem to indicate that we could get on with building ABWRs and ESBWRs as fast as possible now while proving the RBWR concept on a smaller test rig (the 60MWe reactor apparently proposed by Hitachi) and then refit the first build of reactors into RBWRs as convenient.

Later build reactors could be constructed specifically for the pancake RBWR core and its shortened, reduced cost, pressure vessel.

[trag]

Jan 17, 2013 2:57:13 GMT 9.5 @Douglas Wise said:

Cyril,

I'm becoming increasingly concerned that, while we all take pleasure in airing our views on optimum nuclear technology, years go by without any sign of a large scale nuclear renaissance.

It's difficult to get a full speed nuclear build going when the folks who have control of the climate issue oppose nuclear and favor unreliables. How much has been squandered on wind and solar installations over the last fifteen years? How many nuclear reactors would that have bought?

It would seem that Germany alone could have built at least sixteen more reactors with the money they've poured down the unreliables rat-hole. That would come to something like 60 million tons of coal per year not burned or almost 200 million tons of CO2 per year that they could be not emitting.

Sigh.

The "greens" claim they care about the climate, yet all their institutions have done everything in their power to prevent effective CO2 reductions, i.e. the building of nuclear reactors.

Before we can get nations to be serious about building nuclear reactors, we're going to have kill this idea that wind or solar can supply our energy needs.

[cyrilr]

Douglas Wise - fair enough. An S-PRISM being built would be a good thing.

Edireland - thank you for the critique. Let me put a few points in.

1. On load refuelling - the European project has an interesting solution: the fuel rods have metal extensions so that they can be manipulated in the gas space, avoiding troublesome in-lead manipulation (as lead is fairly opaque all the way through to the gamma spectrum...).

2. Mass of lead - yes, certainly the European project and even the Berkeley salt cooled project, have learned that the sodium pool designs aren't directly Xerox-able to their designs. Shorter pools must be used. I should point out also, that all nuclear reactors must manage heavy spent fuel, which weighs almost as much as lead. IFR fuel is much heavier still, with uranium metal fuel twice the weight of lead, and a tighter pitch to diameter ratio. Weight isn't so much a problem as volume, though, as volume determines the weight of the construction as well. IFRs have a lot of volume in the double walled steam generators and secondary loops. Not needed in lead fast reactors...

3. Noncondensables in the ICs. Yes, agree, all newer BWRs that I reviewed already have DW to WW vent lines for purging the noncondensables. It's why the TEPCO statement of hydrogen in the IC was surprising to me.

I like ICs. The European lead cooled project uses them in the design. Each SG has an IC. The ICs of the lead cooled reactor are easier to maintain and design, as they involve condensing nonradioactive steam (eg significant hydrogen and fission products are never present).

I like BWRs too. The ESBWR, ABWR, ABWR-II, EU-ABWR and Kerena (formerly SWR-1000) are all very attractive and safe designs. These are all build-able right now or in a few years.