User:Pat Palmer/sandbox/test2

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Nuclear power is a controversial topic, and some of the controversies remain unsettled, even after the facts in the article are agreed on. This Debate Guide 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.

Safety

Radioactive gases

Critiques of MSR safety on p.91 of Lyman 2021:

"MSR developers often say that cesium-137 and certain other troublesome fission products do not present a problem because they remain chemically bound in the liquid fuel and are not released. However, this is misleading because it only applies to those isotopes that are generated directly in the fuel from fission. It does not apply to isotopes that are produced indirectly by the decay of noble gas fission products only after the gases are released from the fuel.

For instance, in addition to being produced directly by fission, cesium-137 also results from the decay of short-lived xenon-137, which has a 3.82-minute half-life. Indeed, nearly all of the cesium-137 generated in a nuclear reactor is produced through xenon-137 decay rather than directly by fission."

"MSR developers say little about this issue and how they expect reactor operators to manage and dispose of large quantities of high-level cesium-137 waste."

"Another troublesome radionuclide, tritium, with a halflife of 12.5 years, is highly mobile and cannot be effectively captured. Even with a costly off-gas control system, MSRs would almost inevitably discharge far more tritium and other radioisotopes into the environment during normal operation than solid-fueled reactors."

Notes from ThorCon's 2020 IAEA report:

p.11 "The off-gas processing system uses
helium sweep gas to entrain Xe and Kr gasses, passing them slowly through the off-gas cooling tanks within the Can where most of the Xe-135 decays to Cs-135 that is trapped there. The He, Xe, and Kr gas mixture then flows from the Can through two hold-up tanks and a charcoal delay line in the secondary heat exchanger cell. The gas flow continues to a cryogenic gas processing system to separate the gasses, storing stable Xe and radioactive Kr-85 in gas bottles and returning He for reuse as a sweep gas."

p.13 "Inert gas in the annulus between the cold-wall and Can captures tritium that may permeate
the Can or Fuelsalt Drain Tank. A getter system removes the tritium from the inert gas."

p.13 "The solar salt loop captures any tritium that has made it to the secondary loop, and ensures that a rupture
in the steam generator does not release harmful chemicals."

p.34 "The hold-up tanks contain no radioactive materials because once the off-gas leaves the Can,
the daughter products of the gases are not radioactive. So the only radioactive materials are
tritium and Kr-85. The Kr and Xe gas bottles will be removed and sold."

Editor's Note: ThorCon's 2020 filing does not directly address the concern about Cs-137 in Lyman's 2021 report. There is also no discussion of this alleged problem in a very thorough design study from Oak Ridge National Laboratory: Robertson 1971. The cover gas chapter describes the expected releases in detail.

Robertson, R C. CONCEPTUAL DESIGN STUDY OF A SINGLE-FLUID MOLTEN-SALT BREEDER REACTOR.. United States. https://doi.org/10.2172/4030941

Reply to a question on a different Molten Salt Reactor in Renewables vs Nuclear Debate How does Cesium get “released from the core” in Elysium's FC-MSR design?:
"In general it doesn't but any losses would likely be as CsI into the offgas system, where a chiller condenses/captures it."

Comments from a discussion in Quora.com:
"As for the gas issue, this stinks as a red herring, as it insinuates that off-gassing is something that hasn’t been considered to date, which would only be the case if the engineers attached to these projects were incompetent fools. This would have to be extended to the personnel of the several national agencies in various countries that have given initial approval to some of these SMRs."
"Tritium is produced by CANDU reactors in volumes enough that it has to be dealt with and it is to the point where this has become the top global source for this isotope and a bit of a side hustle for CANDU operators."