I does appear that I was hasty, in lumping the Integral Fast Reactor concept in with the liquid fueled fast breeders. They do appear to have addressed a lot of the traditional concerns concerning inherent rather than engineered safety.

I still can’t get past the liquid sodium coolant, though. It’s very hard for me to see how they can claim inherent safety when the liquid sodium coolant can cause hydrogen fires and explosions if exposed to cooling water, even if they have added an intermediate cooling loop.

Can’t they get rid of the cooling water all together? Wouldn’t a gas turbine, as in a gas powered reactor work just as well, perhaps combined with a gas working fluid bottoming cycle?

[JR: I don't oppose nuclear power. I oppose the American taxpayer being forced to take the entire financial risk for every new nuclear power plant and being forced to insure the entire meltdown risk for every new nuclear power plant.

The GOP never specifies exactly what they would do to show 100 nukes down the throats of the American public in 20 years, making it hard to attack their plans other than on general grounds. The public deserves to make an informed decision.]

While I want to make it clear I’m hardly expert about IFR, my understanding is that they are not as bad as you suggest.

The site I linked to is not astroturf but belongs to Barry Brook, a reputable Australian climate scientist who is urging our govt to move faster on the issue. He was originally opposed to all nuclear power until learning about advances in the IFR tech.

Regards some of your criticisms, they’re usually answered in the following ways: apparently liquid sodium as a coolant is also used in other industries and is a well-established and safe technology. The IFR reactors (including a test one built in USA in the 90s) are designed to be passively safe — that means everyone just walks away and does nothing, and it shuts itself down. Finally, IFRs can burn nuclear weapon fissile materials and the dirty waste from PWR (pressurised water reactors, = Gen III) and themselves produce waste with half-lives in the years and decades range and which is very hard to weaponise. It’s said that the current nuclear waste dumps and nuclear weapons have enough fuel to run many of these things for many years (so uranium mining is unnecessary). If you read through the links I provided you’ll find all of this discussed though I guess I’ve got no absolute guarantee of their accuracy, except that Barry Brook and some other scientists I know of have been persuaded.

It’s possible that I’m sounding like I’m a big supporter of these but I’m still trying to learn about them. They sound great but there must be problems with them — I guess one obvious one is that while test facilities were built in the 90s (and seemed to run really well) actual operating IFRs haven’t ever been built so maybe it will take decades to develop designs and build them? But I’m interested to hear cogent criticisms of them.

This sounds like someone has just renamed the liquid metal fast breeder reactors, cooled by liquid sodium, and has changed the name to Integral Fast Reactors.

The websites you guys link to look like Astroturf to me, too.

I used to think these things were really cool, until I learned that sodium burns in air, particularly if exposed to water, and that the primary cooling loop is sodium and the tertiary cooling loop is steam or water.

Another thing I seem to remember is that in the event of an accident, operators would have literally seconds to react.

I’ve always thought it unfortunate that the nuclear industry doesn’t seem to understand that their design criteria should be so slanted toward safety that a nuclear accident becomes effectively impossible. That is the path toward commercial viability, I think.

My information on liquid cooled fast breeder reactors is decades old. I hope that the technology has advanced, but I doubt it.

I think that the French approach to gas cooled reactors is much better than the American approach to water cooled reactors. I think that American approaches are tainted by concerns about efficiency and commercial viability, when what really matters to the public is safety, safety, safety.

It is possible to make inherently safe reactors – Freeman Dyson and General Atomic were involved in such an effort to make a teaching or demo reactor that had inherent, rather than engineered safety, many years ago. Gas cooled reactors equipped with a phase change and neutron absorbing material, that would flood the reactor core in case of an overheating event, might be one way to create a gas cooled reactor with inherent safety.

If we are going to choose an nuclear option, we need inherent safety, not engineered safety.

My understanding of liquid fueled fast breeders is that they are far from inherent safety, rely on engineered safety to prevent accidents, and use highly reactive liquid sodium (contaminated with radioactivity) as a primary coolant.

Is the earth climate system in such danger that we have to choose this as an option?

Maybe so.

But nuclear reactors are carbon neutral at best, and somewhat carbon positive in practice, because of the need to mine and refine uranium, mostly.

Admittedly, fast breeders would manufacture their own fuel, so this is a potential solution to global warming.

What we need is carbon negative energy, IMO. We need to seize the coal fired power plants, and convert them to oxyfuel combustion, biocarbon fuel, a HiPPS topping cycle, and deep injection of the resulting pure stream of CO2.

But perhaps Gen IV isn’t as good as advertised. I’m interested in learning more about it.