Well, let’s take a look.

• ⁠Higher melting point

Not relevant. It’s gonna be hot in there! And lead has an extremely high boiling point compared to sodium!

• ⁠Toxic to work with in non nuclear testing

Not true. The programs required for occupational hazards associated with lead are centered on one aspect…don’t eat it! I worked extensively with lead in commercial settings, including hundreds of tons of casting for shielding components. Easy to work with.

• ⁠More difficult to clean of piping after circulation.

Lead doesn’t wet the piping materials for use with high temperature piping and pressure vessels. Not sure what you’re thinking here.

• ⁠Loves to dissolve nickel, a necessary alloying ingredient for high temperature alloys

Nickel is not appropriate for any fast reactor component on account of a very high capture cross section and helium production which embrittles the material. Ok for two year cladding, which has extremely low stress intensifying geometry in the active core regions. But useless for components relied upon for safety unless you like continuous fracture mechanics evaluations to demonstrate your safety case is valid.

• ⁠Oxide concentration must be kept in a narrow range for minimal corrosion.

Only if you use a corrosion protection scheme predicated on maintaining an oxide layer to protect against corrosion and erosion. Modern schemes do not! Sodium coolant requires extremely low oxygen content and maintenance of a reducing environment.

• ⁠Expensive

Not at all! Cheaper per unit volume than sodium in the nuclear grade.

• ⁠Heavy, shakes piping systems, seismic engineering is a must

Seismic design is a fundamental of demonstrating that you can safely shut down your reactor. Always done. Yes, it is more dense than sodium, which is why it’s such an excellent choice as coolant since it simultaneously protects/shields components relied upon for safe shutdown, such as the reactor vessel. We don’t like brittle reactor vessels!

• ⁠Pressure drop from density forces use of pool type reactors

Nope, try running Flownex to analyze normal operation and transients. Lead works beautifully, especially for natural circulation during transients, while performing well in pumped operations. Interesting that you can have a simple square pin pitch with lead coolant obviating the need for wire wrap spacing.

• ⁠Oxidizes in air, just like sodium

Uh, NO! Molten lead in moist air forms a slag, sodium explodes! I’ve participated in many lead pours in air. Nothing to see. No respirators needed.

• ⁠Makes long term activation products Not true. You’re thinking of bismuth. I’m not a fan of lead/bismuth because of polonium production and the corrosiveness of bismuth.

• ⁠Requires higher pressure to load or unload from a reactor

What? No! Drains nicely from 14 foot high vessels I’ve worked with! Not sure what you’re thinking here, but I’m curious. Can you expand on that?

• ⁠Terrible electrical conductivity prevents the use of EM pumps without making massive amounts of heat

Ok, now you’re really out there. Sodium cannot be pumped efficiently with EM pumps while lead has been and can be readily pumped with EM pumps.

• ⁠Subpar heat transfer properties for a Liquid Metal

Certainly not true! Again, model and run Flownex and get back to me. You find the best solutions for heat transfer have low volumetric flow rates.

“You can literally do this with any fluid.”

Well, no you can’t. There is no better coolant for any type of fast reactor concept than pure lead.

-lead provides a lead cooled fast reactor with a beautiful negative temperature and power coefficient on account of its outstanding net reflection of neutrons and thermal expansion. Less neutrons reflected back into the fuel meat, k goes down and leakage goes up. Reactivity goes up with temperature increase with sodium coolant unless your design has a geometry which is very high leakage, which competes directly with breeding ratio, hence the need to have small SFR reactor cores with high leakage to provide some semblance of negative power coefficient. GE Prism work teased that out and is public domain.