00:00:00
particle accelerators machines that use
00:00:02
electromagnetic fields to speed up
00:00:04
charged particles to near the speed of
00:00:06
light are at the limit the largest and
00:00:09
most complicated devices ever invented
00:00:12
used for everything from probing the
00:00:14
fabric of the universe to treating
00:00:16
cancer these machines are
00:00:18
extraordinarily useful in their ability
00:00:20
to control direct and study the smallest
00:00:23
pieces of the
00:00:24
universe but being so complex and
00:00:27
Powerful particle accelerators also
00:00:29
demand extreme care and caution things
00:00:33
can go wrong people have been hurt in
00:00:37
1992 one such accident born of human
00:00:40
error and a critical lack of resources
00:00:42
answered the question what would happen
00:00:45
if you mistakenly put your hand in a
00:00:47
particle
00:00:49
accelerator this is the true story of
00:00:52
the accelerator accident in Hanoi
00:00:54
Vietnam
00:01:03
the accident occurred here at the 3M
00:01:05
Island nuclear power
00:01:13
plant pulsed in a precise way changing
00:01:16
electromagnetic fields can bend the
00:01:18
paths of and accelerate charged
00:01:21
particles the first circular particle
00:01:23
accelerator what came to be known as a
00:01:25
cyclotron operated on this basic
00:01:27
principle a proton Maro round as its
00:01:30
inventor Ernest Lawrence called it
00:01:33
modern circular particle accelerators
00:01:35
are far more complex than Lawrence's
00:01:37
1930 invention which won him a Nobel
00:01:40
Prize but the underlying idea of
00:01:42
accelerating charge particles in circles
00:01:44
to eventually smash them together and
00:01:46
against objects revolutionized nuclear
00:01:49
physics and has touched almost every
00:01:51
branch of science from the creation of
00:01:53
artificial elements for physics to the
00:01:55
irradiation of tumors for medicine the
00:01:58
real power of a particle accelerator
00:02:00
large or small is not that it can move
00:02:03
Atomic elements quickly it's that they
00:02:05
can move particles as quickly as
00:02:07
physically possible everybody knows
00:02:10
science's most famous equation E =
00:02:13
MC^2 what most people don't know is that
00:02:17
this isn't the full equation it's
00:02:19
actually e^2 = m^2 C 4 + p^ 2 c^ 2 this
00:02:26
second Factor captures the momentum of
00:02:28
some object in everyday life we are free
00:02:31
to ignore this variable because most
00:02:34
objects you're familiar with don't move
00:02:36
very fast at all relative to the speed
00:02:37
of light and therefore the vast majority
00:02:40
of an object's energy can be suitably
00:02:42
approximated simply by multiplying its
00:02:44
mass by light speed this is the equation
00:02:47
that you know however when an object
00:02:50
does approach the speed of light its
00:02:52
momentum dominates its total energy and
00:02:55
this combined with a speed of light that
00:02:57
is equal in all reference frames is
00:02:59
where we get the universal speed limit C
00:03:03
Einstein's full equation can be shown to
00:03:05
depend on just how close an object's
00:03:07
velocity V gets to the speed of light C
00:03:11
but as V gets infinitely closer to C
00:03:14
this Factor will approach Infinity which
00:03:16
means infinite energy which we know
00:03:19
isn't possible and so nothing with mass
00:03:22
can travel at or faster than the speed
00:03:25
of light high energy particle
00:03:28
accelerators like the Large Hadron lier
00:03:30
basically Pro this the LHC the most
00:03:33
complicated machine ever built can
00:03:36
accelerate particles to within just 3 m/
00:03:40
second of the speed of light but no
00:03:43
further
00:03:47
99.999999% of the universal speed limit
00:03:50
a fantastic feat of engineering today
00:03:54
there are an estimated 30,000 particle
00:03:56
accelerators worldwide about half of
00:03:58
them are used to insert ions and
00:04:00
transmute materials useful for
00:04:03
Semiconductor production and the other
00:04:05
half are used in radiotherapy to the
00:04:07
benefits of millions of patients with
00:04:09
the small remainder of accelerators used
00:04:11
in research in 1992 a small laboratory
00:04:15
in Vietnam was conducting research using
00:04:17
another derivative of the cyclotron a
00:04:20
so-called microtron when a concatenation
00:04:23
of design flaws and human error cost a
00:04:26
scientist his hands
00:04:30
in the November of 1992 the Hanoi
00:04:33
Institute of nuclear physics was using
00:04:35
one of its two microtron the Aged
00:04:37
accelerator an experimental model
00:04:39
originally built in 1973 was given to
00:04:42
Vietnam in the HP by the former Soviet
00:04:45
Union the machine in the facility at
00:04:47
sattin was installed according to Old
00:04:49
measurements taken in the USSR there
00:04:52
were no Vietnamese language manuals or
00:04:54
instructions provided the control panel
00:04:57
for the microtron was entirely in
00:04:59
Russian
00:05:00
no Russians worked at The
00:05:02
Institute the hp's only working
00:05:05
microtron was set up to fling electrons
00:05:07
through guide tubes at tungsten and
00:05:09
uranium targets producing X-rays and
00:05:11
neutrons respectively on the 17th of
00:05:14
November the day of the accident the
00:05:17
accelerator was directing electrons at
00:05:19
the tungsten Target which would in turn
00:05:20
produce a conical beam of x-rays inside
00:05:23
of a wooden box that held a sample of
00:05:25
gold ore to be irradiated typically an
00:05:28
experimental sample would be pushed into
00:05:30
or out of the IR radiation Zone by puffs
00:05:33
of compressed air but on this particular
00:05:36
afternoon the facility director decided
00:05:38
that since the first sample was to be
00:05:40
changed in just an hour he could do
00:05:43
everything by hand the first experiment
00:05:46
went according to plan the director and
00:05:49
two assistants removed the first sample
00:05:51
by hand and placed the second in the
00:05:53
path of the x-rays that would scream out
00:05:55
of the tungsten at the speed of light
00:05:58
all Personnel left the concrete maze
00:06:00
encasing the
00:06:01
accelerator just outside the control
00:06:03
room however the director asked an
00:06:05
assistant to get him some soap to wash
00:06:07
up with and apparently walked towards
00:06:09
the sink in the courtyard the assistant
00:06:12
passing by the control room on the way
00:06:14
to the soap told the operator that the
00:06:16
experiment was ready and that the
00:06:18
accelerator was ready to be switched on
00:06:20
what the assistant didn't know was that
00:06:23
instead of going to use the sink the
00:06:25
director decided something was arai with
00:06:27
the experimental setup and returned to
00:06:29
the the microtron without telling anyone
00:06:32
he placed his hands inside the wooden
00:06:34
box and adjusted the gold sample three
00:06:36
or so times over the course of a few
00:06:38
minutes his hands were less than a foot
00:06:41
from the tungsten which unbeknownst to
00:06:43
him was emitting extremely energetic
00:06:47
X-rays at the same time the assistant
00:06:49
had retrieved the soap and arrived at
00:06:51
the courtyard the director wasn't there
00:06:55
she called his name several times and
00:06:57
then ran to the accelerator room the
00:06:59
door was open she shouted again nothing
00:07:04
her voice was apparently drowned out by
00:07:06
the din of generators air conditioners
00:07:08
and cooling systems fearing the worst
00:07:11
the assistant ran down to the control
00:07:13
room to tell the operator to shut down
00:07:14
the accelerator
00:07:16
immediately but by then the director's
00:07:19
hands feeling nothing had been
00:07:21
unintended targets for 2 to 4 minutes
00:07:24
the worried assistant and operator
00:07:26
turned off the machine and ran back to
00:07:28
the accelerator the door was still open
00:07:31
they found the director adjusting the
00:07:32
experiment he passed by them as if
00:07:35
nothing had happened and walked to the
00:07:36
Courtyard to wash his hands that's when
00:07:39
he was told that the machine had been on
00:07:41
for at least a few minutes while he was
00:07:44
inside the international atomic energy
00:07:46
agency's report describes that at this
00:07:49
point the director fell very silent he
00:07:52
walked to a room with a gamma
00:07:54
spectrometer to check if the very atoms
00:07:56
of his hands had been turned Radioactive
00:07:59
the machine showed a well-defined energy
00:08:01
peak of anti-matter annihilations born
00:08:04
of gamma Neutron reactions in organic
00:08:07
tissue at this point the director knew
00:08:11
he had been
00:08:12
irradiated but not how badly over the
00:08:15
next few hours everyone at the HP heard
00:08:18
about the accident but no one did
00:08:21
anything the director rode home on his
00:08:23
motorcycle as usual that night his hands
00:08:26
felt strange but he chocked it up to his
00:08:29
room toid
00:08:30
arthritis after 8 days of inaction his
00:08:33
hands were turning gray but they
00:08:35
functioned normally and an annual
00:08:37
checkup 2 Days Later didn't raise any
00:08:39
questions despite the director telling
00:08:41
his doctor that he had probably been
00:08:44
irradiated she recommended a
00:08:46
dermatologist for a possible vitamin
00:08:48
deficiency the next day his hands were
00:08:51
much harder to ignore they were swollen
00:08:54
and painful still the director continued
00:08:57
to work as normal it wasn't until 24
00:09:01
days after the incident on the 11th of
00:09:03
December that he went to a Specialized
00:09:05
Hospital his hands were now deeply
00:09:08
ulcerated and the tissue was dying the
00:09:11
anonymous director's treatment related
00:09:13
to his irradiation would span the next
00:09:16
600
00:09:17
[Music]
00:09:20
days how do you build a facility that
00:09:22
protects you from radiation while having
00:09:24
a machine that generates intense
00:09:26
radiation at the heart of it the most
00:09:28
effective and deceptively simple design
00:09:30
is a maze like one you'd solve with a
00:09:33
pen and paper only with concrete outside
00:09:36
of accelerators and large
00:09:38
electromagnetic influences charge
00:09:40
particles and photons travel in straight
00:09:42
lines and one of the most efficient ways
00:09:45
to put as much material between you and
00:09:47
a beam of radiation is to put as much
00:09:49
stuff as possible between you and the
00:09:52
source the hard 90° angles of a concrete
00:09:55
maze both maximizes the amount of
00:09:58
material between beam and bodies and
00:10:00
makes it much harder for any surface
00:10:02
Reflections to travel very far the HP
00:10:06
had a maze around its microtron as well
00:10:09
but notice that where the maze was
00:10:11
placed was preventing radiation from
00:10:13
leaking into the courtyard and not the
00:10:16
offices where the scientists worked for
00:10:18
hours on end the maze principle applies
00:10:21
all the way down to the fibers and
00:10:23
cables of a facility anything that
00:10:26
connects a room full of radiation to the
00:10:28
outside world even a service duct should
00:10:30
be oriented in such a way to minimize
00:10:33
the strength of escaping radiation in
00:10:35
this case only allowing scattered
00:10:38
radiation to escape instead of direct
00:10:41
radiation in Hanoi at the time of the
00:10:43
accident cable and ventilation Ducks
00:10:46
passed through walls in straight lines
00:10:49
and the doors of the facility were
00:10:51
parallel without the recommended bends
00:10:53
and Lead traps to block x-rays the most
00:10:57
basic protection at a radiation facility
00:11:00
however is the material surrounding an
00:11:02
accelerator or Source radiation as
00:11:05
particles and photons of any energy will
00:11:07
eventually stop after enough nanoscopic
00:11:10
collisions inside of a material so the
00:11:12
denser the material the better how much
00:11:15
of a material you need for a facility
00:11:17
can be calculated using the so-called
00:11:19
half thickness which is the depth of
00:11:21
some material that will reduce the
00:11:23
intensity of ionizing radiation to 1/2
00:11:26
its initial value the half thickness
00:11:29
concrete with respect to different
00:11:31
radioactive sources can be as small as
00:11:33
an inch which is why it's used for
00:11:35
shielding the world over steel lead and
00:11:38
uranium are even more effective but more
00:11:41
expensive the mt17 microtron shipped
00:11:44
from the Soviet Union and built in Hanoi
00:11:47
without any Vietnamese language
00:11:49
instructions was placed in a facility
00:11:51
with concrete walls of quote unspecified
00:11:54
density no other details were
00:11:57
available it was was later calculated
00:12:00
that the radiation dose rate for those
00:12:02
working every day in the hp's microtron
00:12:05
control room which was never measured a
00:12:07
check shielding efficacy was five times
00:12:10
higher than the ambient levels in the
00:12:12
ghost city of pripet 2 miles outside of
00:12:15
the Chernobyl nuclear power plant and on
00:12:17
the roof of the Institute this dose rate
00:12:20
was 150 times higher than
00:12:25
that the news at Vietnam's Center for
00:12:28
burns wasn't good later investigation by
00:12:31
the iaea would find that the dose rates
00:12:34
where the director's hands were placed
00:12:36
were extremely high 20 to 50 Grays
00:12:39
depending on exactly how long his hands
00:12:41
were adjusting the experiment which he
00:12:44
couldn't remember a whole body dose of
00:12:46
five or more grays is fatal thankfully
00:12:50
because of the directionality of
00:12:52
radiation the director's whole body dose
00:12:54
was minimal but his hands were doomed
00:12:57
from the start the prog pression was
00:12:59
typical for acute radiation injuries
00:13:01
forever festering wounds that defy
00:13:04
treatment and refuse to heal they would
00:13:06
get better then much worse within a few
00:13:10
weeks it was clear drastic measures had
00:13:12
to be taken three skin grafts were
00:13:14
attempted from January through February
00:13:17
two of them failed in March an iaea
00:13:20
physician recommended removing the most
00:13:22
damaged finger it was amputated on the
00:13:25
23rd of March 1993 and sent to a
00:13:28
biophysics lab in Moscow for study a
00:13:32
Grizzly decision but very useful you
00:13:35
don't often get an irradiated human body
00:13:37
part to research 159 days after the
00:13:41
incident the director was moved to a
00:13:42
hospital in Paris in May another finger
00:13:46
was removed and the right hand was
00:13:48
surgically embedded in the director's
00:13:49
own abdomen with the hopes of preventing
00:13:52
infection and encouraging tissue
00:13:54
growth on day 190 the right hand was
00:13:57
removed from this natur pocket the left
00:14:00
hand improved the right never did the
00:14:04
director's right hand was amputated at
00:14:06
wrist level on July 9th
00:14:09
1993 at this point the director's left
00:14:12
hand appeared to be on the menend but as
00:14:15
is the Sinister nature of radiation
00:14:17
injuries the damage isn't skin deep in
00:14:20
October necrosis returned to the fourth
00:14:23
and fifth fingers on his remaining Hand
00:14:25
by the 443rd day after exposure both
00:14:29
damaged fingers had been removed all
00:14:32
that could have been saved at the
00:14:33
director's hands which wasn't very much
00:14:36
had been he was finally discharged after
00:14:39
moving in and out of hospitals for
00:14:41
almost 600 days the accelerator incident
00:14:45
in Hanoi is overshadowed in nuclear
00:14:47
history by the most famous accident of
00:14:49
the same type when Anatoli bosi
00:14:52
accidentally placed his head in a
00:14:54
particle
00:14:55
beam it's mostly famous for what didn't
00:14:58
happen Anatoli
00:15:00
survived it begs the question why didn't
00:15:03
Anatoli lose his head when the director
00:15:06
in Hanoi lost most of his
00:15:09
hands I believe it has something to do
00:15:11
with what is known as the brag peak of
00:15:13
different kinds of radiation protons
00:15:16
electrons photons and other particles
00:15:18
each have their own interactions with
00:15:20
matter as such each deposits its energy
00:15:24
along the path of travel
00:15:26
differently Anatoli burgos's head encoun
00:15:28
entered a proton beam which deposits the
00:15:31
majority of its energy more than 20 cm
00:15:34
into humanlike tissue since 20 cm is
00:15:38
longer than most human heads are deep
00:15:41
the majority of the energy that hit
00:15:43
Anatoli did not stop in his brain if it
00:15:47
had he would have died instantly the
00:15:50
Hanoi director's hands encountered an
00:15:53
x-ray beam comprised of photons these
00:15:56
deposit the majority of their energy
00:15:58
very quickly before moving through much
00:16:00
tissue the depth of an average hand is
00:16:03
within this peak and therefore the
00:16:05
intense energy of the microtron in Hanoi
00:16:08
did not peacefully pass through it
00:16:10
fatally irradiated most of the tissue it
00:16:13
touched This was later confirmed by an
00:16:15
iaea member visiting Vietnam after they
00:16:18
placed a fresh chicken leg in the path
00:16:20
of the same beam and checked it for
00:16:23
antimatter
00:16:27
annihilations it was the opinion of of
00:16:29
the international atomic energy agency
00:16:31
that the accident in Vietnam was bound
00:16:33
to happen the developing country owing
00:16:36
to a serious lack of resources did not
00:16:38
have established radiation protection
00:16:40
infrastructure there were no trained
00:16:42
inspectors to tour facilities the Hanoi
00:16:45
facility was built based on foreign
00:16:47
language instructions from the Soviet
00:16:49
Union there was no radiation monitoring
00:16:51
equipment to tell Personnel that when
00:16:53
the machine was on they were receiving a
00:16:56
dose higher than walking around
00:16:57
Chernobyl
00:16:59
there were only handwritten manuals for
00:17:01
equipment and nothing for radiation
00:17:03
protection
00:17:04
procedures a radiation times for the
00:17:07
microtron had no automatic cutoffs and
00:17:09
were instead timed by wristwatch staff
00:17:12
relied on Word of Mouth that no one was
00:17:14
in the accelerator room before the
00:17:16
machine was switched on the list of
00:17:18
faults can and does go on quote the
00:17:22
standard of radiation safety at HP
00:17:25
before the accident was so low that an
00:17:28
accident
00:17:29
was not
00:17:30
unlikely after iaea intervention the HP
00:17:34
fitted a magnetic interlock and padlock
00:17:36
to the accelerator room door an alarm
00:17:38
near the microtron that the control room
00:17:40
could sound was installed other buttons
00:17:43
and lights inside and outside the
00:17:44
accelerator room were added and
00:17:46
integrated as there was quote a
00:17:48
fundamental need to inculcate a sense of
00:17:51
responsibility for safety a safety
00:17:53
culture in all concerned end quote
00:17:57
Vietnam by the IA EA's estimation had
00:18:00
prioritized meeting the immediate needs
00:18:02
of the country that nuclear physics and
00:18:04
research can provide not nuclear safety
00:18:08
the engineers and scientists at the
00:18:09
Hanoi Institute of nuclear physics had
00:18:11
the highest academic qualifications
00:18:13
possible but they did not have the
00:18:15
training resources or regulatory
00:18:18
oversight to prevent one of the worst
00:18:20
particle accelerator accidents in
00:18:22
history as is so often the case in these
00:18:25
stories it wasn't an intrinsic feature
00:18:27
of nuclear physics physics or
00:18:29
engineering that caused human harm no it
00:18:32
was all to human behavior guessing the
00:18:35
positions of personnel wanting to change
00:18:37
an experiment by hand to save time
00:18:40
assuming that if you can't feel
00:18:41
something nothing is happening in the
00:18:45
summer of 1994 after losing the majority
00:18:47
of his hands the anonymous facility
00:18:50
director returned to
00:18:52
Hanoi until next time
00:18:56
[Music]
00:19:04
[Music]
00:19:18
[Music]
00:19:24
[Music]
