
Demon Core: The Strange Death of Physicist Louis Slotin - jseliger
http://www.newyorker.com/tech/elements/demon-core-the-strange-death-of-louis-slotin?mbid=social_twitter
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flashman
Sounds like 'normalisation of deviance': when something is dangerous but has
previously been done without incident, so it becomes standard procedure. NASA
has some guidelines on eliminating it from your practices and systems:
[https://sma.nasa.gov/docs/default-source/safety-
messages/saf...](https://sma.nasa.gov/docs/default-source/safety-
messages/safetymessage-normalizationofdeviance-2014-11-03b.pdf?sfvrsn=4)

~~~
peejaybee
I'm not sure I would go that far. Some considered Slotin's methods dangerous:
'Enrico Fermi himself had warned Slotin that he would be “dead within a year”
if he continued'.

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Bromskloss
Depiction of the accident in the film "Fat Man and Little Boy":
[https://youtube.com/watch?v=0ZFPio2PeQc&t=6m24s](https://youtube.com/watch?v=0ZFPio2PeQc&t=6m24s)

Scary.

~~~
JoeDaDude
There is a fact-based dramatization of the incident on the Dark Matters TV
show. Look for Season 2, Episode 4:

[https://www.youtube.com/watch?v=HPFhKUt245E](https://www.youtube.com/watch?v=HPFhKUt245E)
(Edited video source)

~~~
lobster_johnson
Link with exact time:
[https://youtu.be/HPFhKUt245E?t=1625](https://youtu.be/HPFhKUt245E?t=1625)

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pdkl95
Speaking of criticality accidents... apparently Feynman had to convince a army
colonel that the team doing the 235U enrichment at Oak Ridge _need to be
informed about the physics_ of what they were working with. Had he been
unsuccessful, a much larger criticality "excursion" would have happened.

In the setup/practice runs of the enrichment facility they were using big
carboys to move uranium nitrate solution. Nobody told them that water (as a
moderator) would significantly amplify the chain reaction! According to
Feynman, "...the plant would never work, it would have blown up - I swear it
would've."[1]

[1]
[https://www.youtube.com/watch?v=hTRVlUT665U#t=2106](https://www.youtube.com/watch?v=hTRVlUT665U#t=2106)

~~~
cnvogel
And indeed, many of the criticality accidents listed on the Wikipedia page
[https://en.wikipedia.org/wiki/Criticality_accident](https://en.wikipedia.org/wiki/Criticality_accident)
happened while handling fissile material in solution.

There is a very interesting book on criticality accidents, which includes
photographs and sketches on laboratory layout etc.: McLaughlin, T.P., Monahan,
S.P., Pruvost, N.L., Frolov, V.V., Ryazanov, B.G. and Sviridov, V.I., 2000. A
review of criticality accidents 2000 revision (No. LA-13638). Los Alamos
National Lab., NM (US).
[https://www.orau.org/ptp/Library/accidents/la-13638.pdf](https://www.orau.org/ptp/Library/accidents/la-13638.pdf)

~~~
pinewurst
Thanks for that great reference!

Another worthwhile read is "Nuclear Accidents" by James Mahaffey.

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jackgavigan
I always found it interesting that only one person died in each "Demon Core"
incident, despite the burst of radiation being so intense that it caused the
blue flash. Mind you, many of the survivors suffered health problems that were
likely caused by the incidents later in life:
[http://www.orau.org/ptp/pdf/accidentsurvivorslanl.pdf](http://www.orau.org/ptp/pdf/accidentsurvivorslanl.pdf)

~~~
codezero
Interestingly the blue flash was caused by electrons, which had been excited
by the radiation, transitioning back to a lower energy state and giving off
photons!

The reason people survived is because radiation from a source falls off by the
inverse square law, so as long as you have a small source and a short burst of
radiation, distance is great. It's more surprising to me that they didn't use
more remote devices for these kinds of experiments.

~~~
YeGoblynQueenne
>> It's more surprising to me that they didn't use more remote devices for
these kinds of experiments.

They did, but these also caused accidents. See the Lady Godiva device:
[https://en.wikipedia.org/wiki/Godiva_device](https://en.wikipedia.org/wiki/Godiva_device)

 _Otto Frisch received a larger than intended dose of radiation when leaning
over the original Lady Godiva device for a couple of seconds. He noticed that
the red lamps (that normally would flicker intermittently when neutrons were
being emitted) were 'glowing continuously'. Frisch's body had reflected some
neutrons back to the device, causing it to go critical, and it was only by
quickly leaning back and away from the device and removing a couple of the
uranium blocks that Frisch escaped harm but, he said, "if I had hesitated for
another two seconds before removing the material ... the dose would have been
fatal". On 3 February 1954 and 12 February 1957, accidental criticality
excursions occurred causing damage to the device, but fortunately only
insignificant exposures to personnel. This original Godiva device was
irreparable after the second accident and was replaced by the Godiva II._

If I understand this correctly (the closest I got to being a nuclear phycisist
is having met an astrophycisist once) this happened during the setup of an
experiment. I think normally the experiments with this device were sort of
automated (they dropped a rod between two masses, so gravity killed the
reaction quickly).

[[https://en.wikipedia.org/wiki/Criticality_accident#Recorded_...](https://en.wikipedia.org/wiki/Criticality_accident#Recorded_incidents)]

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okket
Follow-up analysis: "The blue flash" by Alex Wellerstein

[http://blog.nuclearsecrecy.com/2016/05/23/the-blue-
flash/](http://blog.nuclearsecrecy.com/2016/05/23/the-blue-flash/)

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Sanddancer
I'd seen from a lot of other sources that the demon core was used in
Crossroads Able, which also caused hearings and investigations due to it being
dropped a significant distance from its intended point. Anyone have any better
proof one way or another to say for certain what the Demon Core's fate was?

~~~
vilhelm_s
Alex Wellerstein just made a blog post which elaborates on how he knew it was
melted down. Apparently the source is personal communication with Glenn
McDuff, a retired scientist at Los Alamos.

[http://blog.nuclearsecrecy.com/2016/05/23/the-blue-
flash/](http://blog.nuclearsecrecy.com/2016/05/23/the-blue-flash/)

~~~
Sanddancer
Thanks. That definitely sheds more light, even though I will admit I have some
partiality to the romantic notion that it was jinxed even in its last
excursion into criticality.

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sammydavis
Amazing that it working on that stuff was an individual experiment, with your
hands in the mix!

~~~
userbinator
People knew in general far less about the effects of ionizing radiation at the
time --- you could even say Slotin's death was one of the datapoints that lead
to better understanding.

~~~
ufmace
I just finished watching the TV series Manhattan, about the Manhattan project.
It was supposedly written with help from historians and physicists who know
their stuff. This reminded me of one of their plot points that seemed
realistic - a character suffered a potentially dangerous exposure, and the
base doctor, feeling out of his depth, tries to reach out to somebody who
knows better. After a few hours of chasing bureaucracy and secrecy, he
eventually discovers that the official expert is listed as himself! There
really isn't anybody who has any idea how exposure affected people, and
they're just pushing ahead anyways because it's wartime.

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Aelinsaar
It was, even by the standards of the day, incredibly careless.

~~~
Bromskloss
I've been thinking the same, but might it be that being in such a hurry made
them choose not to device a safer experimental setup?

~~~
Aelinsaar
No, and there had already been an accident with this very core.
[https://en.wikipedia.org/wiki/Harry_K._Daghlian_Jr](https://en.wikipedia.org/wiki/Harry_K._Daghlian_Jr).
Sadly, there was no good reason for this, just a young cocky guy. Not a bad
man, and we've all made stupid choices, but his sadly was a bit historically
significant.

~~~
goldenkey
I like the adage, "We all start with a bag of luck, filled, and a bag of
experience, empty.

The trick is to fill your bag of experience up before your bag of luck runs
out -- ie. when your bag of luck runs out, you die. Most people have a couple
events in their life where they almost died -- of course we know we should
have never made those choices -- but its easier said now that we have the
experience knowing we got "lucky." :-)

~~~
Aelinsaar
I've never heard it put that way, but I've had this conversation with friends
before, "Hey, remember when we almost died doing 'X'?" You're right,
absolutely right.

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calibraxis
> Slotin instructed one of his colleagues to lay radioactivity-detecting film
> badges around the area, which required the scientist to go dangerously close
> to the still overheated core.

Many managers and coworkers are so unthinking about their coworkers' health.
Even without plutonium.

~~~
optforfon
That part didn't make sense to me. Why does it stay more radioactive for a
period of time after the accident? The pieces are separated - shouldn't it
return to it's previous state? .I can understand it heating up (though can't
you just cool it down mechanically?) but that's not really the same

~~~
hga
Because lots if not most of the fission products are themselves very unstable,
and will be decaying towards more stable isotopes in due course. I doubt this
radioactivity was a fraction as dangerous as the criticality excursion he
caused (and I'm sure he wasn't in a normal frame of mind after his screwup,
which I'm sure he knew could eventually kill him), so it's a hopefully
moderate at worst personal harm vs. unique opportunity to collect data trade
off.

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YeGoblynQueenne
>> various items that were near the core—a bristle brush, _an empty Coca-Cola
bottle_ , a hammer, a measuring tape.

:groan:

