3 ms·

To the best of my understanding, graphite in reactors serves the purpose of moderating nuclear chain reactions. The radioactive materials in the forest are almo

by grey413 13y ago

To the best of my understanding, graphite in reactors serves the purpose of moderating nuclear chain reactions. The radioactive materials in the forest are almost certainly not dense enough to undergo a chain reaction, so adding a moderator would be pointless. The issue isn't the environmental radiation (like you might worry about standing next to an exposed nuclear core), it's the prospect that radioactive materials might be absorbed by people (like you might worry about if a nuclear core was on fire in the same city as you). Spreading moderators around would do nothing to help about bioaccumulation.

dctoedt 13y ago
> The radioactive materials in the forest are almost certainly not dense enough to undergo a chain reaction, so adding a moderator would be pointless. ... Spreading moderators around would do nothing to help about bioaccumulation. That's basically correct. There won't be a fission chain reaction because essentially no neutrons are released by the radioactive decay of the isotopes in the fallout. Consequently, deploying neutron moderators would have essentially no effect. (It'd be like, say, taking a life jacket with you on a hike through the Sahara.) The relevant radioactive isotopes are mainly caesium 137, iodine 131, and strontium 90 [1]. When they decay into other elements, they release beta- and gamma radiation, which can damage nearby cells if ingested into the body. But none of them fissions to release neutrons that would be absorbed by graphite or boron. The danger posed by these isotopes is that if you inhale or swallow them, they can stick around in your body tissues, zapping nearby cells, for a long time. For example, caesium 137 has an estimated biological half life of 70 days [2], while strontium 90, which is taken into bone much like calcium, has an estimated biological half life of 18 years [3]. A major forest fire in the Chernobyl area would turn contaminated trees into contaminated smoke. Who knows where the wind would blow the smoke. The resulting fallout could be inhaled and/or swallowed by people and other animals. It also might fall on farmland, where it could be up-taken by crops that would eventually be swallowed. All in all, not good news. (Source: I used to be a Navy nuclear engineering officer.) [1] http://www.who.int/ionizing_radiation/chernobyl/backgrounder/en/ http://www.who.int/ionizing_radiation/chernobyl/backgrounder... [2] http://en.wikipedia.org/wiki/Caesium-137#Health_risk_of_radioactive_caesium http://en.wikipedia.org/wiki/Caesium-137#Health_risk_of_radi... [3] http://en.wikipedia.org/wiki/Strontium-90 http://en.wikipedia.org/wiki/Strontium-90
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todayiamme 13y ago
As dctoedt pointed out it appears that I might be wrong in this case, I had assumed that the fallout was producing significant neutron radiation which interacted with its surroundings to produce greater amounts of radiation. Adding a moderator in that circumstance should have reduced the burden a bit in theory.
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by grey413 13y ago

dctoedt 13y ago

> The radioactive materials in the forest are almost certainly not dense enough to undergo a chain reaction, so adding a moderator would be pointless. ... Spreading moderators around would do nothing to help about bioaccumulation. That's basically correct. There won't be a fission chain reaction because essentially no neutrons are released by the radioactive decay of the isotopes in the fallout. Consequently, deploying neutron moderators would have essentially no effect. (It'd be like, say, taking a life jacket with you on a hike through the Sahara.) The relevant radioactive isotopes are mainly caesium 137, iodine 131, and strontium 90 [1]. When they decay into other elements, they release beta- and gamma radiation, which can damage nearby cells if ingested into the body. But none of them fissions to release neutrons that would be absorbed by graphite or boron. The danger posed by these isotopes is that if you inhale or swallow them, they can stick around in your body tissues, zapping nearby cells, for a long time. For example, caesium 137 has an estimated biological half life of 70 days [2], while strontium 90, which is taken into bone much like calcium, has an estimated biological half life of 18 years [3]. A major forest fire in the Chernobyl area would turn contaminated trees into contaminated smoke. Who knows where the wind would blow the smoke. The resulting fallout could be inhaled and/or swallowed by people and other animals. It also might fall on farmland, where it could be up-taken by crops that would eventually be swallowed. All in all, not good news. (Source: I used to be a Navy nuclear engineering officer.) [1] http://www.who.int/ionizing_radiation/chernobyl/backgrounder/en/ http://www.who.int/ionizing_radiation/chernobyl/backgrounder... [2] http://en.wikipedia.org/wiki/Caesium-137#Health_risk_of_radioactive_caesium http://en.wikipedia.org/wiki/Caesium-137#Health_risk_of_radi... [3] http://en.wikipedia.org/wiki/Strontium-90 http://en.wikipedia.org/wiki/Strontium-90

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todayiamme 13y ago

As dctoedt pointed out it appears that I might be wrong in this case, I had assumed that the fallout was producing significant neutron radiation which interacted with its surroundings to produce greater amounts of radiation. Adding a moderator in that circumstance should have reduced the burden a bit in theory.

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