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<div class="moz-cite-prefix">As practical jokes go, having a planet
with oceans that go critical is pretty impressive. <br>
<br>
On 26/11/2013 16:31, spike wrote:<br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p><br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Here’s
something cool: the Pu alpha decays to 240Np, which is
denser, so it sinks toward the center, but really doesn’t
have time to go far with that hour half-life to 240Pu, but
then the concentration of 240Pu goes up and heats up, so I
suppose it would boil, but under enormous pressure perhaps
not, so it isn’t clear if a critical mass eventually
results.</span></p>
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<br>
It is worth considering the neutron reflectivity properties of the
original Pu too: it might act as a neutron mirror, in which case the
critical mass goes down. Hmm, those alpha particles might also mess
things up a bit. Not sure they have an effect, I need to check my
literature. Wikipedia mentions that alphas can incite fission in
Pu240, I have not yet checked out
<a class="moz-txt-link-freetext" href="http://prola.aps.org/abstract/PR/v144/i3/p1046_1">http://prola.aps.org/abstract/PR/v144/i3/p1046_1</a><br>
<br>
Hmm, if the Pu gets close to critical I assume there would be
mini-explosions or flare-ups that would be like mega-boiling: high
concentration zones have chain reactions, heat up a lot, turn to big
nuclear vapour bubbles and mix the ocean. You would only get a big
detonation if it all quietly congregated together and then something
eating the neutrons suddenly disappeared.<br>
<br>
So maybe there would not be a big boom, just regular geysers of
molten metal and nuclear plasma. Still awesome.<br>
<br>
<span
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hey
I wonder if the feds are getting nervous watching me google
around on plutonium and uranium?</span></p>
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<br>
It is when you start downloading neutron diffusion codes they get
really nervous... <br>
<br>
<br>
<br>
<pre class="moz-signature" cols="72">--
Anders Sandberg,
Future of Humanity Institute
Oxford Martin School
Faculty of Philosophy
Oxford University </pre>
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