The Ergosphere
Tuesday, June 25, 2019
 

Deconstructing HBO's "Chernobyl"

Thunderf00t does a bang-up job:




Edit:  Thunderf00t is a good storyteller but weak on the nuclear stuff.  Here are my notes, addressed as an open letter to him:

First, you missed a completely obvious way to debunk the "5 megaton" garbage.  It only took 10 megatons to completely erase the island of Elugelab in the Ivy Mike test.  5 MT would have scoured Pripyat off the ground and turned the entire Chernobyl power plant to vapor.  Instead, most of the reactor building was still standing!  That wasn't a megaton or even kiloton-level explosion; it was worth, at most, a few hundred pounds of TNT.

Second, you've got a whole lot of your concepts about nuclear fission pretty badly wrong.

The reason that low-enriched uranium can't make a bomb is because you literally cannot sustain a chain reaction in pure LEU, or even LEU oxide, no matter how much of it you have.  The detail of "cross sections" comes to bite you; a fission neutron straight from a nucleus is about as likely to be absorbed by a U-238 nucleus that it goes near (and make no further neutrons) as it is to be absorbed in passing by a U-235 nucleus.  With U-238 being vastly more abundant, fission neutrons can't replace themselves and the "reaction" has no "chain"; the chain gets broken almost immediately.

So, how did the Chicago crew create a chain reaction in natural uranium (just 0.711% U-235)?  They had a MODERATOR, in the form of a big pile of relatively pure graphite bricks.  The graphite, almost pure carbon, only rarely tends to absorb neutrons but does a fairly good job of slowing them down as the neutrons bounce around.  And as the neutrons slow down, a funny thing happens:  U-235 atoms are HUGELY more successful in catching slow ("thermal") neutrons than U-238 atoms are.  When you get things slowed down JUST enough that each fissioning atom leaves neutrons that wind up splitting exactly one more atom, the chain goes unbroken:  you have a self-sustaining "chain reaction".  But for this to work, the moderator has to be between the fuel elements and slow neutrons down before they can get sucked up by U-238 or escape entirely.

What does this have to do with a reactor meltdown?  As soon as the fuel melts and runs together, it loses the moderation because the moderator is now outside the fuel mass, not between bits of it.  Ergo, the chain is broken and the reaction stops.  (In reactors using water as a moderator, losing the water also shuts down the chain reaction.  Chernobyl used graphite.)

But that doesn't stop the heat.  The OTHER thing you neglected is that the fission reaction itself is not the only source of heat in a reactor!  About 6.5% of the energy actually comes from the radioactive decay of the fission products, the daughter nuclei created by the splitting atoms.  This heat does not stop when the chain reaction stops; you have to wait for the material to "cool" as the "hottest" fission products decay away.  The stuff that decays the fastest releases heat the fastest, and goes away fastest.  Within an hour the "afterheat" is down to 1.5%, 0.4% after a day and 0.2% after a week.

Maybe you want to re-record some of your narration on your video to get those details right.  Just sayin'.

PS:  No I was not drunk when I wrote this, just fat-fingered.  All typos spotted have been corrected.



 
 

Taiwan steel mishap confirms radiation hormesis

This paper should be shaking the world.  It should have turned our radiation-exposure standards upside-down.  It should have established that regular low-dose radiation exposure is our best prophylactic against both cancer and birth defects.  Yet nothing of the sort has happened.

Well, what happened?  FTP:
Abstract — The conventional approach for radiation protection is based on the ICRP’s linear, no threshold (LNT) model of radiation carcinogenesis, which implies that ionizing radiation is always harmful, no matter how small the dose.  But a different approach can be derived from the observed health effects of the serendipitous contamination of 1700 apartments in Taiwan with cobalt-60 (T½ = 5.3 y).  This experience indicates that chronic exposure of the whole body to low-dose-rate radiation, even accumulated to a high annual dose, may be beneficial to human health.

Approximately 10,000 people occupied these buildings and received an average radiation dose of 0.4 Sv, unknowingly, during a 9-20 year period.  They did not suffer a higher incidence of cancer mortality, as the LNT theory would predict.  On the contrary, the incidence of cancer deaths in this population was greatly reduced – to about 3 per cent of the incidence of spontaneous cancer death in the general Taiwan public.  In addition, the incidence of congenital malformations was also reduced – to about 7 per cent of the incidence in the general public.
The paper contains this graph of cancer mortality:

This paper should be shaking the world.  It should have turned our radiation-exposure standards upside-down.  It should have established that regular low-dose radiation exposure is our best prophylactic against both cancer and birth defects.

Nothing of the sort has happened.  Nothing.

Why?

Are the people in charge of our "health" evil, or just stupid?

Edit:  Backup paper link https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2477708/

Edit 2:  Contrary paper:  https://www.ncbi.nlm.nih.gov/pubmed/18666807

I find the contrary paper suspicious.  It's held behind a paywall, so the basis for the conclusions will not be examined by very many people.  This is exactly what a scientific fraud would do.


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More dangerous than Three Mile Island

Three Mile Island.  The name still elicits fear, forty years later.  Yet the whole accident had zero casualties; there were no deaths and no injuries.

The list of energy-related accidents with greater tolls is long.  Natural gas pipeline explosions have killed quite a few in just the USA alone.  Oil wiped out the center of Lac Megantic in 2013, killing 47.  And collisions between road vehicles and coal trains regularly kill and injure, mostly in ones and twos.

To this list of energy-related dangers we now must add... utility-scale batteries:
PHOENIX (AP) — Arizona's largest electric company installed massive batteries near neighborhoods with a large number of solar panels, hoping to capture some of the energy from the afternoon sun to use after dark.
Arizona Public Service has been an early adopter of battery storage technology seen as critical for the wider deployment of renewable energy and for a more resilient power grid.
But an April fire and explosion at a massive battery west of Phoenix that sent eight firefighters and a police officer to the hospital highlighted the challenges and risks that can arise as utilities prepare for the exponential growth of the technology.
Despite the very small number of units in service, this is not the first battery fire.  It won't be the last, either; current plans involve many more and much bigger installations.  Running up a list of casualties while being such a minor component of the electric system ought to have people asking questions, like...

"Are these things safe to have in my neighborhood?"
"Are these things safe to have anywhere?"

Anyone who dares to ask those questions, though, is bound to come under vicious attack from the proponents of "renewables".  Meanwhile, those same proponents spread fear of nuclear power, despite nukes being objectively much safer than even smallish utility-scale batteries.

Evil, or just crazy?  It's got to be one or the other.

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