ThorCon nuclear reactor/Debate Guide

Nuclear power is a controversial topic, and some of the controversies remain unsettled, even after the facts in the article are agreed on. This Discussion page will provide a concise summary from each side of these unsettled issues. Much of this discussion is collected from internet forums, and we welcome updates to improve these summaries.

Risk of proliferation

Union of Concerned Scientists report: "Advanced" Isn't Always Better, Edwin Lyman (2021).
https://www.ucsusa.org/resources/advanced-isnt-always-better
“We studied the most prominent 'advanced' nuclear reactor designs. Unfortunately, few are safer or more secure than current generation reactors.”
From the Executive Summary:
“All MSRs chemically treat the fuel to varying extents while the reactor operates to remove radioactive isotopes that affect reactor performance. Therefore, unlike other reactors, MSRs generally require on-site chemical plants to process their fuel. MSRs also need elaborate systems to capture and treat large volumes of highly radioactive gaseous byproducts.”

From Jack Devanney, Principal Engineer, ThorCon USA Inc:
“For the record, ThorCon does no chemical processing online to remove fission products or anything else. Xenon and krypton bubble out in the header tank, are held in storage tanks until they have decayed to harmless levels, and then cooled, compressed and stored. There's nothing elaborate or complex about the process.”

Waste Management

For more discussion see the Discussion page of Nuclear waste management

Radioactive gases

Comment in a discussion of nuclear waste in the FaceBook group Renewable vs. Nuclear Debate
"What are they going to do with the radioactive gases and the corrosive, radioactive salt from thorium reactors? ...the engineers designing MSR's don't know yet exactly, what kind and what amounts of radioactive waste will be produced, while physicists like Harald Lesch for example warn about the storage of used, radioactive salts. And recycling of nuclear waste is a no-go in the US of A"

See the replies from Jack Devanney above, and from Roger Blomquist in the discussion linked above.

What about non-fuel waste

Question in the FaceBook group Renewable vs Nuclear
"all the stuff on the primary loop. Pipes, pumps, wiring, blah blah. Obviously there is going to be mechanical and chemical wear on parts and they will need to be replaced like any power plant relying on heat -> steam -> turbine -> generator process. Parts will be be additionally exposed to neutrons and presumably undergo nuclear reactions and I assume some of those reactions will compromise their mechanical properties... eventually. How big of a deal is this? Is it slow, fast? What is the balance of fuel waste to non-fuel waste? Where do these parts go?"

Answer from World Nuclear Association Recycling and reuse of materials from decommissioning

Recycling materials from decommissioned nuclear facilities is constrained by the level of radioactivity in them. This is also true for materials from elsewhere, such as gas plants, but the levels specified can be very different. For example, scrap steel from gas plants may be recycled if it has less than 500,000 Bq/kg radioactivity. This level however is one thousand times higher than the clearance level for recycled material from the nuclear industry, where generally anything above 500 Bq/kg may not be cleared from regulatory control for recycling.

Answer from Captain Roger Blomquist, United States Navy (retired) 8 Feb 2022:
"There are small concentrations of activated structural elements like cobalt. These typically have half-lives of years, not multiple decades. If they are recycled, then the workers doing the recycling will need to take (sometimes expensive) precautions to minimize their radiation exposure. I doubt that any such exposures would be harmful, although some might be. The precautions are quite likely far in excess of what is needed to prevent actual health effects."

Question on Quora.com

How big a problem is irradiated steel and other non-fuel waste from a nuclear power plant?

Add image caption here.

Answer from Lyle McElhaney 30 March 2022:
Iron is an element that is difficult to make radioactive.

This table shows that iron-56, which is almost 92% of all naturally occurring iron, requires three neutron absorptions before it becomes radioactive, and two absorptions for another 2% of the material. A single absorption is a low probability event for any given iron nucleus; absorbing three is a low probability to the third power. If it does happen, it results in iron-59 which beta decays to cobalt-59 (stable) with a half-life of 45 days.

Of course, it also shows that about 6% of iron will become unstable with the absorption of a single neutron. The resulting isotope decays by electron capture, which does not emit a particle other than a neutrino, and results in manganese-55, which is stable. So, no harm done by that other than possibly some gamma-rays.

The cobalt-59 resulting from a triple neutron capture could catch another neutron, becoming the dreaded cobalt-60, nemesis of the cobalt bomb. Cobalt-60 has a powerful gamma-ray emission as it beta decays with a half-life of around 5 years. This requires, as noted, 4 successive neutron captures with an intervening beta decay after the third. It is a very small probability event in concept; I don’t know what it is in practice.

Other materials - some do become radioactive when drenched with neutrons for an extended time. One would need to know what materials to analyze what happens.

Question in the FaceBook group Americans for Nuclear Energy
I've heard that the steel gets brittle. Is that just the surface? Can it be annealed with a torch and returned to service, or do we have to discard 343 tons of radioactive steel every 8 years?

Answer from Ed Pheil, Chief Technology Officer, Elysium Industries
There are multiple types of steel damage. The type limiting Thorcon to 8 years is fluoride salt corrosion. Less limiting are neutron displacement damage. This is bulk steel damage, not surface. It can be partially annealed by heating the stainless steel to 650C for hours. Another damage is an (n, alpha) reaction in the nickel creating bulk nickel. Annealing makes the helium migrate to grain boundaries, making it more brittle. Also not limiting.
Further there is creep damage, due to high temperature, not neutrons, also not limiting.
The question is the rate of accumulation of each type of damage. Fluoride salt is more corrosive in a radiation field due to radiation creating free Fluorine ions (F-). They chose to use type 316 stainless steel because it is qualified & cheap, unlike Hastalloy-N. Enough cheaper to warrant 8 yr replacement, but also they would have a qualified material to be able to build "today".

Editorial discussion

see the ../editorial page for more discussion on editorial issues.

one of these has been built recently Apparently, these are not a new idea, but are being reconsidered. See New Molten Salt Thorium Reactor First Time (in) Decades. I know next to nothing about this, but put the link here in case this might help flesh out this article. Eventually, this article could use a better introduction. Coming to it as an uninformed, undecided reader, the current intro is too sparse for me to get my bearings. Pat Palmer (talk) 12:10, 1 November 2021 (UTC)

The article is just a starter with info I picked up from the ThorCon website. Hopefully we will get an expert to jump in and "flesh" it out. Molten salt reactors are some of the first ever built. See the MSRE (Molten Salt Reactor Experiment) back in the 1960's at Oak Ridge. For reasons controversial to this day, they decided to abandon a successful demo and go with PWRs (Pressurized Water Reactors). ThorCon is a straightforward upscale of these early reactors. David MacQuigg (talk) 16:09, 4 November 2021 (UTC)

A brief history of this kind of reactor would be nice in the opener. As a reader, I'd like to know if any of these exist already (when, where etc).Pat Palmer (talk) 12:43, 22 April 2022 (CDT)

And, is this the one where reactor modules get decommissioned after 4 years of use, allowed to "cool down" in place, and then removed/replaced with a new modules? If so, I'd like to see that in the article. It may be over in the WP version...sorry to be confused. Rushing about here.Pat Palmer (talk) 12:46, 22 April 2022 (CDT)

This old version of the article on WP: https://en.wikipedia.org/w/index.php?title=ThorCon_nuclear_reactor&oldid=850279880 includes some history and origin details near the top related to ORNL. In my view, this article would benefit from including more context and history about the origin of the ThorCon ideas, both here and at WP. I had wondered all along where this design "came from". This old version gives a rather succinct history of the design right at the top. Who began the design? Where has it been tested? Where WILL it be tested, and when? I have no idea if the information is accurate, but the level of detail seems right.Pat Palmer (talk) 08:54, 2 May 2022 (CDT)

There is some good historical material on this and other liquid fuel reactors at ThorConPower.com/history I can add some of this and other design information in a section at the end of the article. I started to do that on the WP version, but had to give up when one of the WP editors insisted we make it the main focus of the article, not just a subsection. This is the way it goes on WP. Everyone gets to add their stuff, and it turns the article into a tedious mush. I suspect also, that the editor insisting on changing the focus was anti-nuclear, and his statements about the original article being "propaganda" reflected his bias. David MacQuigg (talk) 19:14, 9 May 2022 (CDT)