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A comment on Safer Nuclear Reactors Are on the Way. Parent comment

Re:Safer Nuclear Reactors Are on the Way by pfdietz on Saturday July 06, 2019 @07:43AM (#20369160)
The radioactive gas was probably noble gases like krypton and xenon. They'd have to be careful with the xenon, as 137Xe decays to dangerous 137Cs (halflife 3.8 minutes). The idea "all the radioactivity stays in the salt" can be wrong, as that xenon could deposit the cesium outside the salt if it bubbles out quickly enough.

135Xe also can be removed (halflife ~9.2 hours). It is famously a very powerful neutron poison with important effects on reactor operation; those advocating thermal breeders count on it being removed before it soaks up neutrons. But this leads to an increase in production of its decay product, 135Cs, which has a halflife of 2.3 million years.

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Re:Safer Nuclear Reactors Are on the Way by achalhp on Tuesday July 09, 2019 @05:16AM (#20390104)
MSRE had a charcoal-bed off-gas system which safely stored all the noble gases. It was cooled and shielded with water, similar to today's PWRs. PWRs also have water chemistry control and resin-bed filters for primary loop which is highly radioactive and shielded. Construction of the off-gas system is described in pages 58-60 in ORNL-3708: Molten-Salt Reactor Program: Semiannual Progress Report for the Period Ending July 31, 1964 https://energyfromthorium.com/pdf/ORNL-3708.pdf
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