The HBO mini-series Chernobyl reintroduced the world to the nuclear catastrophe that
occurred on April 26th, 1986 at the Chernobyl nuclear reactor in the Soviet Union, in what
is now Ukraine.
The series followed the tragedy that befell the region after the accident and the efforts
made by some heroic people to prevent further damage.
In this video, we will discuss the scientific accuracy of some key aspects from this widely
popular show.
*This video only covers the accuracy of the science mentioned in the show and does not
verify the historical accuracy of the events.
First, let’s talk about what the show got right in terms of scientific accuracy.
Taste of metal The line “Do you taste metal?” comes up
multiple times in the first episode of the series.
The control room operators and the first-response firefighters seem baffled by the taste of
metal in their mouths.
The most straightforward reason for this would be the presence of plumes of radioactive isotopes
of Strontium-90, Caesium-137, and Zirconium-95 metals being released into the air around
the reactor.
Two other factors that would result in a metallic taste are exposure to large doses of radiation
and the presence of ozone in one’s surroundings.
Along with the visible nuclear fallout, the failing reactor also released huge amounts
of radiation in the form of alpha, beta, and gamma rays.
The highly energetic gamma rays shooting out from the exposed core can easily penetrate
clothes and skin to enter the body.
The people near the plant right after the explosion didn’t have special protective
clothing around their neck and head.
Gamma rays are known to affect the salivary glands and taste buds, which could produce
a metallic taste.
This effect is often reported by patients undergoing radiation therapy for cancer.
The nuclear gamma rays also possess enough energy to transform the diatomic oxygen in
the atmosphere and in our mucus membrane into triatomic ozone.
Unlike oxygen, which is odorless, this stratospheric savior has an odor that could be described
as metallic, reminiscent of burning wire.
The Cherenkov Effect The blue shaft of light that Lyudmila Ignatenko
sees from her apartment after the explosion is attributed to the “Cherenkov effect”,
explained later in the series.
It is a real phenomenon that is often likened to the optical counterpart of a sonic boom,
when charged particles in a transparent medium travel faster than light.
Nothing can beat light in a race when in vacuum conditions, but light can sometimes be slowed
in other mediums.
The gamma rays from the exposed core, while not faster than the speed of light in vacuum,
travel faster than light in water and air.
The high-energy stream of gamma particles ionizes every atom and molecule in its path
to an excited state, resulting in an eerie blue glow known as the “Cherenkov light”.
Such light is often seen near the reactor pools of nuclear power plants.
Stable Iodine Pills In the show, a female doctor at the Pripyat
hospital asks her colleague if they stock iodine pills; later, Ulana Khomyuk advocates
for the distribution of stable iodine pills to tackle radiation symptoms.
Stable iodine isn’t some magic pill that turns people radiation-proof, but it does
stop a tiny gland in our body from getting confused.
Our thyroid gland uses iodine (I) to produce hormones.
The iodine-hungry thyroid doesn’t know how to differentiate between radioactive (Iodine-131)
and non-radioactive (Iodine-127) forms.
Iodine-131 is a common fission product of nuclear chain reactions that can cause considerable
damage to the thyroid gland and increase the chances of thyroid cancer if exposed beyond
safe limits for an extended period of time.
Stable iodine or potassium iodide (KI) pills act as gatekeepers to stop radioactive I-131
from being absorbed by the thyroid.
Potassium iodide solution or pills contain enough stable iodine to keep the thyroid full
for almost 24 hours.
A regulated and timely dose of stable iodine can protect the thyroid against the side effects
of exposure to radio-iodine.
Workings of an RBMK reactor With RBMK reactors at the heart of the plot,
the mini-series did an excellent job of explaining the science of reactors to millions of viewers.
If you somehow missed or forgot the brilliant court presentation with the red and blue cards,
here’s a quick recap on how RBMK reactors work.
An RBMK or high-power channel reactor is a water-cooled nuclear reactor that uses radioactive
Uranium as fuel and graphite as a moderator to slow the speed of flying neutrons.
But wait, doesn’t graphite increase reactivity?
Yes, graphite does enhance reactivity because it doesn’t remove the neutrons from the
reaction, it just slows them down.
This type of reactor has 6 major parts: The fuel rods, the control rods, the graphite
moderator, the pressure tubes, the steam generators, and the concrete shielding.
The uranium fuel generates heat via nuclear fission, and then pressurized water is pumped
into the core via tubes; the water then absorbs heat, which turns water into steam, the steam
turns the turbines and generates electricity.
The fuel and the graphite moderators act as positive drivers, meaning that they increase
the reactivity of the system.
These reactions are stabilized by the negative drivers: Boron carbide control rods and Xenon-135,
which is a reactor “poison” produced by the fuel core itself.
These two agents absorb and remove neutrons from the system, thereby throttling it.
Then we have water, which increases reactivity in its steam form, but acts as a coolant otherwise.
For this entire process to run steadily, a tight balance must be maintained between positive
and negative drivers.
For a better understanding of RBMK reactors, please visit the link in this video’s description.
Now, let’s move into the territory of dramatization and creative liberties.
Radioactive victims Radioactive contaminants can spread through
external sources, such as polluted water, food, soil, or surfaces, but they aren’t
contagious like the flu.
One can’t “catch” radiation from a radiation-poisoned patient by just touching or being near them.
The scene where the clothes of all the firefighters and plant workers were dumped in the basement
to prevent further contamination was pretty accurate, but the same can’t be said about
the supposedly “radioactive patients”.
Internal contamination does happen when someone ingests or breathes in radioactive material,
but that’s not what happened to the patients being treated at the Moscow hospital 6.
The operators and the responders were exposed to high doses of gamma radiation, which can
neither be stopped nor trapped inside our bodies.
So, once the contaminated clothes are removed and patients are bathed, there is hardly any
chance of contamination by contact, and certainly not enough to make other people ill.
Fetus absorbing radiation One of the most heart-wrenching moments in
the show is when Ulana mentions fetuses absorbing radiation to keep their mothers alive.
Though tear-jerking and dramatic, this fact is fortunately plain medical fiction.
Firstly, as we discussed, radiation syndrome doesn’t transmit like a typical pathogen,
and secondly, fetuses aren’t made of special biological material that can act as radiation
sponges.
In fact, a pregnant woman’s body would provide an effective shield to the fetus against exposure
to lower levels of radiation.
A rise in birth defects was observed in the aftermath of the Hiroshima-Nagasaki bombings.
However, pregnant women close to the bombing site were directly exposed to a dangerously
high dose of radiation, along with internal contamination from atomic bomb fallout.
Spontaneous bleeding Alexander Yuvchenko, a plant employee, is
seen spontaneously bleeding from his abdomen after he props up the door to the reactor
hall for his colleagues to inspect the interior.
Such bleeding can occur due to bone marrow failure, which is a common symptom of acute
radiation syndrome amongst people exposed to a high dose of radiation above 70 rads.
However, this stage of the syndrome is reached weeks after the radiation exposure and is
usually followed by a recovery period, where the patient appears to be recovering.
Bleeding out without any external injury mere minutes after being exposed to radiation is
highly improbable.
Nuclear reactors cannot explode like nuclear bombs
One of the most crucial purposes of any reactor design is to prevent any chance of it going
BAM!
like a bomb.
Even though nuclear reactors and nuclear bombs both work on the same principle of a fission
reaction, they aren’t interchangeable.
In a nuclear bomb, the highly radioactive fuel is tightly packed into a compact core
to prevent any energy or neutron loss after the fission chain reaction is initiated.
With nothing to buffer or absorb the high-energy neutrons, the fuel mass quickly gets supercritical,
a point where more neutrons are being produced than lost.
This leads to an enormous outwards release of energy and hence, the massive explosion
within a matter of seconds.
On the other hand, nuclear reactors are designed to remain critical, where the same number
of neutrons are being produced as are being lost.
This is attained with the help of control rods and strategic fuel rod design.
In a reactor, the fuel rods are safely separated from each other.
They are usually covered in metal piping and have moderating materials between each rod
that can regulate the flying neutrons from the fuel in order to maintain a slow and sustained
chain reaction.
Also, in terms of fuel, atomic bombs contain a very high percentage of enriched U-235,
which is a highly unstable isotope.
On the other hand, in nuclear reactors, the fuel is a mixture of U-235 and a stable U-238
isotope, providing better control over the fission speed.
At the end of the day, HBO’s Chernobyl is a dramatic mini-series and not a documentary,
so expecting it to be 100% technically accurate in its portrayal of events would be asking
too much.
In May of 2019, Google saw a sudden search spike for the terms “RBMK reactor”, “radiation
sickness” and “Chernobyl”.
There is no harm and no foul in fictionalization, so long as it creates a healthy and informed
dialogue among the viewing population.
The mini-series Chernobyl succeeded, and quite remarkably, in doing just that!