China Says It's Closing in on Thorium Nuclear Reactor

[apatheticonion]

I have been doing my best to find critical information on the viability of Thorium based nuclear reactors (because they sound too good to be true).

Everyone sings their praises, but what engineering challenges are there and are those engineering challenges large enough to discourage their development/adoption?

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

It generally sounds really promising - even the Wiki page for thorium MSR sings its praises.

Why wouldn't it work? Why isn't the world throwing shit-loads of money at this? Is China enlightened or is this some kind of meme-ware technology they fell for (or are trying to convince others to waste their money on)?

[philipkglass]

Here's a well cited perspective, written by one of HN's own active commenters:

https://whatisnuclear.com/thorium-myths.html

[pfdietz]

Here's a useful slide deck from ORNL (2017):

https://gain.inl.gov/SiteAssets/MoltenSaltReactor/Module2-Ov...

Note page 23! Almost all the 137Cs ends up outside of the core, due to sparging of precursors. "Over 40% of [fission products] leave core"

Lots of other issues, particularly with radiation damage and corrosion of reactor structural elements. Unlike in a solid fuel reactor, there is fission going on right at the boundary of the salt. In a LWR, there is a layer of water between the fuel and the reactor structure to provide shielding. There will be non-fuel components of a MSR that are not lifetime components, but will have to be swapped out due to degradation. Some MSR designs are proposing to just swap out the entire reactor vessel because of this.

[lamontcg]

> 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.

[arcticbull]

Extant CANDU reactors can utilize Thorium fuel too. [1] I believe India is planning to utilize them in this way. [2]

[1] https://www.osti.gov/etdeweb/servlets/purl/20823329

[2] https://en.wikipedia.org/wiki/CANDU_reactor

[haecceity]

Existing energy industry is too entrenched in current technology to innovate? Widely publicized nuclear energy disasters prevents popular support? I don't know but this guy seems pretty smart

https://www.youtube.com/watch?v=1EFfxMx6WJs

[credit_guy]

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

[fallingfrog]

China built the world’s largest high speed rail network (24,000 miles of tracks) and the first rails were laid down in 2007.

If you think they can’t do this in 9 years, you haven’t been paying attention.

[j_walter]

Nuclear is far from the best source of electricity, but it is far less damaging to the environment than coal or NG if handled and designed properly. If countries can work together to put them in places that protect from major earthquakes or other natural disasters then I think we can get some decent movement on reduce GHG emissions from power plants.

[godelski]

> Nuclear is far from the best source of electricity

Just to be clear, this is a universal statement. The issue is that there are many factors to consider. There's cost, storage, total output, CO2 and waste production, physical footprint, environmental factors, local resources, and many other parameters that need to be considered when determining what _combination_ of energy sources should be used for an area. I believe that often people abstract these variables out and only concentrate on cost and a secondary factor that supports their point for the specific conversation. We should not be naive and recognize that these are extremely complex systems with equally complex solutions that require significant amounts of nuance to accurately discuss.

[DennisP]

One nice thing about a molten salt reactor like China is building is that the dangerous fission products are chemically bound in the salt. If some external event breaks the reactor wide open, the salt cools and you just have radioactive rocks there on the site, instead of a radioactive cloud over a large region.

[timbit42]

How long does it take to plan and build a nuclear plant? At the rate solar, wind and energy storage are improving, will it be worth the wait? Solar has dropped in price by more than 80% in the past 10 years.

[vbezhenar]

Fusion electricity is what will provide humanity with energy for centuries to come. It'll be available very soon and until then it does not really matter whether we will use nuclear or coal. We just need a final push for 50-100 years and energy issue will be solved once and forever. All the environment issues will be dealt with, when we will have a free energy and better technologies. Spending too much effort on cleaning environment now is not wise.

[tpmx]

That would be awesome, but unfortunately the CCP have proven to us that we can't trust their word.

[tablespoon]

> That would be awesome, but unfortunately the CCP has proven to us that we can't trust their word. Over and over again.

IMHO, claims like this from them should be believed 100%, because to do otherwise invites complacency.

[Someone]

Reading the article, there aren’t huge scientific problems building these reactors. So, if there’s government support, it seems likely to me these will be built.

I also think China has proven that it is willing and able to rapidly build infrastructure. That makes me think their timeline can be in the right ballpark, too.

They also seem to have been willing to sacrifice quality for speed in large infrastructure projects, though (https://en.wikipedia.org/wiki/Wenzhou_train_collision, https://www.reuters.com/article/idINIndia-40638820090627, https://www.npr.org/2012/08/29/160231137/chinese-blame-faile...)

That’s something I would worry more about (disclaimer: China is huge, so it will have its share of disasters. It also probably will pay more attention to nuclear projects than to bread-and-butter concrete pouring for buildings and roads)

[acidburnNSA]

This guy on Twitter named Conrad Knauer [1] who has been diligently following satellite photos and cross-referencing them with the design publications for TMSR-1 that makes it all seem pretty believable. Pretty round-about way to verify things but it's something.

[1] https://twitter.com/ConradKnauer

[jdavis703]

They say they’re 9 years away. That’s a long enough date that I’d be skeptical of any government that was giving a prediction for nearly a decade out.

[CyanBird]

You ought read the article rather than post your own mindless prejudices and mental cliches

Hackernews styles itself of thoughtful discussion

[antman]

My thinking is that for major projects they mostly deliver against our intuition. What are the counter examples which are over and over again?

[thinktankie]

Thank goodness China’s energy policy is not contingent on whether or not tpmx of Hackernews believes them or not.

[duairc]

> CCP has proven to us that we can't trust their word. Over and over again.

Are you able to substantiate that claim?

[defaultprimate]

China says a lot of things

[guscost]

This could also be a feint to get DoD money into the technology.