China Says It's Closing in on Thorium Nuclear Reactor

> The biggest thing I have found is that the salt solution for Thorium reactors is quite corrosive and that is challenging to contain.

If you can figure out the molten salt problem you can replace the nuclear reactor with concentrated solar thermal and get solar baseload power without having to worry about meltdowns for way less than the cost of a nuke plant.

Hm, reading that, it doesn't seem to disprove or actually illuminate that much IMO:

Misconception #1: I assume this is listed first because it is the biggest reason Thorium reactors weren't pursued? But really most MSR people seem to view it as political, and the bullet points in "Misconception #1" only underline that.

Misconception #2: Almost all MSR presentations seem to assume a fissile "ignition" supply of uranium, that isn't hidden. And it seems to dovetail with the political opposition, since the regulatory agencies will block the supply of fissile uranium to start an MSR with. So this point seems to again highlight artificial/bureaucratic blockades.

Miconception #3: Well, ok, this seems to be a decent answer based on the fundamentals of the science and engineering.

Misconception #4: This seems to ignore the fact that a very very small amount of uranium is naturally fissile, while the Thorium all breeds to fissile. It also spouts off about seawater extraction, which hasn't happened AFAIK. This answer seems very misleading.

Plus, the fact the author is from a competing design (a pebble design I believe, and one of the reasons pebble designs seem to exist is because of the prohibition on research labs from booting up a liquid reactor).

I do agree the unknowns are the vessel degradation from the salts, but materials engineers these days are just so amazingly good.

It just seems frustrating that the overarching influence of regulatory agency stubbornness and lobbying influence of solid fuel rod reprocessors and other fuel makers (who have a monopoly on nuclear fuel production I believe due to the regulatory agencies) is evident in this article.

If it is true that China gets breeder/thorium/liquid reactors going, it all doesn't matter. The US will be a decade behind, and with the anti-nuclear opinions of the US voting populace, that will afford the entrenched interests cover to keep suppressing nuclear.

I suppose it doesn't matter right now. Solar/Wind/Battery is improving so quickly you can't forecast/target a price/budget for a reactor design that is invariably 5-10 years out.

It matters geopolitically speaking in a big way, since any significant improvements to nuclear reactors built by China will have corresponding potential for improvement in their nuclear powered submarines and their future aircraft carriers which are being designed around a similar electric power heavy design philosophy as the US Navy’s Gerald Ford class, with the Chinese Type 004 aircraft carriers being designed as “full size” nuclear powered carriers using electromagnetic catapults to their launch aircraft.

Big = expensive. We are talking about two EPR 1600 MWe gen3 reactors here. The parent is talking about SMRs, small modular reactors.

"The plant, which has a projected lifetime of 60 years, has an estimated construction cost of between £19.6 billion and £20.3 billion"

"Financing of the project is still to be finalised, but the construction costs will be paid for by the mainly state-owned EDF of France and Chinese state-owned China General Nuclear Power Group (CGN)"

"In September 2019, further costs were identified that bring the estimated total to £22.9 billion, and may further delay operations. The involvement of state-owned CGN was also questioned after it was sanctioned by the United States government for espionage."

"The European Commission has previously estimated £24.5 billion, including financing costs during construction"

So, an additional £2.6bn (~13%) cost overrun and geopolitics involving China. The EU estimation is +£4.2 bn. There were also competions ahead of schedule despite the pandemic, so it's not all that bad [1].

UK offshore wind also has a capacity factor of

  1. https://en.wikipedia.org/wiki/Hinkley_Point_C_nuclear_power_station
  2. https://energynumbers.info/uk-offshore-wind-capacity-factors
  3. https://www.bbc.com/news/uk-scotland-north-east-orkney-shetland-57991351

Nuclear reactors are complex beasts. Very complex. For example, here's [1] the webpage with NRC's safety evaluation documents for NuScale's small modular reactors. Dozens of documents, totaling more than one thousand pages. In many cases, there are years of work behind a single paragraph. Here's [2] an example where the NRC replies to some concerns raised by some advisory committee regarding some potential scenarios where the reactor may turn unsafe because of some boron technicality:

  >>4.Operator recovery actions raise the possibility of an influx of deborated water into  the core, which may result in recriticality, return to power, and the potential for  core damage.    Staff Response: In the staff’s SER for Chapter 19, dated July 17, 2020,  (ADAMS Accession No. ML20196L734), the staff identified two post-event  recovery scenarios that could pose a challenge to reactivity control. The first  scenario is recovery from a non-LOCA extended decay heat removal system  (DHRS) cooling condition which can occur following initiating events such as  general transients and losses of off-site power. The second scenario is recovery  from a LOCA ECCS cooling condition which can occur following initiating events  such as breaks in the primary coolant lines. The staff notes that either action to  inject would likely be governed by plant-specific procedures; however, such  procedures are not required at the design certification stage and have not been  developed. The staff evaluated the potential core damage risk for the two  scenarios. For reasons discussed in the SER which are supported by two  papers developed by the Office of Nuclear Regulatory Research (RES) (ADAMS  Accession Nos. ML20191A069 and ML20205L317), the staff concludes that  enough margin exists such that these recovery scenarios are unlikely to lead to  core damage based on the physical effects of fluid mixing, reactivity feedback  mechanisms, and associated time constants. Based on the SER and the two  RES papers, the staff found that there is reasonable assurance that there are no  known significant risk contributors that are unaccounted for and that the identified  risk insights are acceptable to support the uses of probabilistic risk assessment  (PRA) at the design stage.

My point is: there are plenty of corner cases, maybe thousands, and in many of these corner cases the outcome can be either a nuclear boom, or at least a Chernobyl or Fukushima scenario. They are low probability but high danger scenarios, so you need to spend a lot of time (and research money) to either rule out each corner case, or to develop foolproof mitigants.

When people say that this or that reactor design is inherently safe, they are talking about first order effects. When the NRC goes into all the details, things always get a bit more complex.

Edit: by the way, nuclear fission reactors can be supercritical (all current commercial ones), or subcritical (those need an external source of neutrons or protons, such as an accelerator). Only subcritical reactors [3] can be truly pasively safe. There are concepts of subcritical reactors that use Thorium as a fuel, but that's not what China is trying here. China is trying a classical Thorium reactor, where Thorium is used to breed fissile Uranium (not the classical U-235, but rather the isotopes U-232 and U-233), and that Uranium in turn proceeds to undergo the (supercritical) fission chain reaction.

[1] https://www.nrc.gov/docs/ML2002/ML20023A318.html

[2] https://www.nrc.gov/docs/ML2023/ML20231A598.pdf

[3] https://en.wikipedia.org/wiki/Subcritical_reactor