The Chernobyl disaster
dennyreno
Nuclear Power Plant in Ukraine, then part of the Soviet Union. It is
considered to be the worst nuclear power plant disaster in history and
the only level 7 instance on the International Nuclear Event Scale. It
resulted in a severe release of radioactivity into the environment
following a massive power excursion which destroyed the reactor. Two
people died in the initial steam explosion, but most deaths from the
accident were attributed to radiation.
On 26 April 1986 01:23:45 a.m. (UTC+3) reactor number four at the
Chernobyl plant, near Pripyat in the Ukrainian Soviet Socialist
Republic, exploded. Further explosions and the resulting fire sent a
plume of highly radioactive fallout into the atmosphere and over an
extensive geographical area. Four hundred times more fallout was
released than had been by the atomic bombing of Hiroshima.[1]
The plume drifted over extensive parts of the western Soviet Union,
Eastern Europe, Western Europe, Northern Europe, and eastern North
America, with light nuclear rain falling as far as Ireland. Large
areas in Ukraine, Belarus, and Russia were badly contaminated,
resulting in the evacuation and resettlement of over 336,000 people.
According to official post-Soviet data,[2] about 60% of the
radioactive fallout landed in Belarus.
The accident raised concerns about the safety of the Soviet nuclear
power industry, slowing its expansion for a number of years, while
forcing the Soviet government to become less secretive. The countries
of Russia, Ukraine, and Belarus have been burdened with the continuing
and substantial decontamination and health care costs of the Chernobyl
accident. It is difficult to accurately quantify the number of deaths
caused by the events at Chernobyl, as the Soviet-era cover-up made it
difficult to track down victims. Lists were incomplete, and Soviet
authorities later forbade doctors to cite "radiation" on death
certificates.[3]
The overall cost of the disaster is estimated at $200 billion USD,
taking inflation into account. This places the Chernobyl disaster as
the most costly disaster in modern history.[4][unreliable source?]
The 2005 report prepared by the Chernobyl Forum, led by the
International Atomic Energy Agency (IAEA) and World Health
Organization (WHO), attributed 56 direct deaths (47 accident workers,
and nine children with thyroid cancer), and estimated that there may
be 4,000 extra cancer deaths among the approximately 600,000 most
highly exposed people.[5] Although the Chernobyl Exclusion Zone and
certain limited areas remain off limits, the majority of affected
areas are now considered safe for settlement and economic activity.[6]
The abandoned city of Pripyat with Chernobyl in the distance
Radio-operated bulldozers being tested prior to use
Abandoned housing blocks in Pripyat
Contents
[hide]
* 1 The Chernobyl nuclear power plant
* 2 The accident
o 2.1 Planning the test of the safety device
o 2.2 Conditions prior to the accident
o 2.3 Fatal experiment
o 2.4 Immediate crisis management
+ 2.4.1 Radiation levels
+ 2.4.2 Fire containment
+ 2.4.3 Evacuation of Pripyat
+ 2.4.4 Steam explosion risk
+ 2.4.5 Debris removal
* 3 Causes of the disaster
* 4 The effects of the disaster
o 4.1 International spread of radioactivity
o 4.2 Radioactive release (source term)
o 4.3 Health of plant workers
o 4.4 Residual radioactivity in the environment
+ 4.4.1 Rivers, lakes and reservoirs
+ 4.4.2 Groundwater
+ 4.4.3 Flora and fauna
* 5 Chernobyl after the disaster
o 5.1 Chernobyl today
+ 5.1.1 Lava-like Fuel Containing Materials (FCMs)
+ 5.1.2 Degradation of the lava
o 5.2 Possible consequences of further collapse of the
Sarcophagus
o 5.3 Grass and forest fires
* 6 Recovery process
* 7 Assessing the disaster's effects on human health
* 8 In the popular consciousness
* 9 Commemoration of the disaster
o 9.1 Chernobyl 20
* 10 Representations in games
* 11 See also
* 12 Further reading
* 13 References
* 14 External links
The Chernobyl nuclear power plant
Location of the Chernobyl Nuclear Power Plant
Main article: Chernobyl Nuclear Power Plant
The Chernobyl station ( [show location on an interactive map]
51°23′14″N 30°06′41″E / 51.38722°N 30.11139°E / 51.38722; 30.11139)
is near the town of Pripyat, Ukraine, 18 km (11 mi) northwest of the
city of Chernobyl, 16 km (10 mi) from the border of Ukraine and
Belarus, and about 110 km (68 mi) north of Kiev. The station consisted
of four RBMK-1000 nuclear reactors, each capable of producing 1
gigawatt (GW) of electric power, and the four together produced about
10% of Ukraine's electricity at the time of the accident.[7]
Construction of the plant began in the late 1970s, with reactor no. 1
commissioned in 1977, followed by no. 2 (1978), no. 3 (1981), and no.
4 (1983). Two more reactors, no. 5 and 6, also capable of producing 1
GW each, were under construction at the time of the disaster.
Chernobyl wanted to build two more reactors for the Chernobyl nuclear
power plant.
The accident
On 26 April 1986 at 1:23:45 a.m., reactor 4 suffered a massive,
catastrophic power excursion, resulting in a steam explosion, which
tore the top from the reactor, exposed the core, and dispersed large
amounts of radioactive particulate and gaseous debris (mostly
Cesium-137 and Strontium-90)[8], allowing air (oxygen) to contact the
super-hot core containing 1,700 tonnes[9] of combustible graphite
moderator; the burning graphite moderator increased the emission of
radioactive particles. The radioactivity was not contained by any kind
of containment vessel (unlike most Western plants, Soviet reactors
often did not have them[10]). Radioactive particles were carried by
wind across international borders.
Planning the test of the safety device
During the daytime of 25 April 1986, reactor 4 ( [show location on an
interactive map] 51°23′22″N 30°05′56″E / 51.38944°N 30.09889°E /
51.38944; 30.09889) was scheduled to be shut down for maintenance as
it was near the end of its first fuel cycle. An experiment was
proposed to test a safety emergency core cooling feature during the
shut down procedure.
A very large amount of cooling water is needed to maintain a safe
temperature in the reactor core. The reactor consisted of about 1,600
individual fuel channels and each operational channel required a flow
of 28 tonnes of water per hour. There was concern that in case of an
external power failure the Chernobyl power station would overload,
leading to an automated safety shut down in which case there would be
no external power to run the plant's cooling water pumps. Chernobyl's
reactors had three backup diesel generators. The generator required 15
seconds to start up but took 60-75 seconds to attain full speed and
reach its capacity of 5.5 MW required to run one main cooling water
pump.
A rotor of a modern day steam turbine
This one-minute power gap was considered unacceptable and it was
suggested that the mechanical energy (rotational momentum) of the
steam turbine could be used to generate electricity to run the main
cooling water pumps, while it was spinning down. Because generator
voltage varies with its rotational speed, a special device is required
to provide stable voltage to the main cooling water pumps as the
turbine spins down. This safety device—a voltage regulating system—was
to be tested during a simulated power "blackout". In theory, it should
have been able to provide power for 45 seconds and thus bridge the
power gap between the onset of the external power failure and the full
availability of electric power from the emergency diesel generators.
The reactor was designed such that it needed coolant even when not
actively operating. In case of an external power failure, the reactor
would automatically scram; control rods would be inserted and stop the
nuclear fission process (and hence steam generation). However, in the
spent fuel, the fission products themselves were highly radioactive,
and continued to produce heat as they decayed. This could amount to
1-2 percent of the normal output of the plant. If not immediately
removed by coolant systems, the heat could lead to core damage.
The amount of spent fuel, and thus the amount of decay heat that the
cooling system must handle, increased throughout operation and
attained its maximum value at the end of the fuel cycle. In the event
of core damage, the end of the fuel cycle would present the worst
possible point in time, with the maximum accumulated inventory of
nuclides to be released into the environment. The experiment would
have been far safer to carry out with fresh fuel. This means that the
simulated power blackout experiment was performed at the most
dangerous point in the reactor cycle.[11]
It was a design requirement that the rotational momentum of the steam
turbine, as it spun down, could be used to generate electricity to run
the cooling water pumps to bridge the power gap. A previous test had
been unsuccessful. Apparently, the test had not been completed
successfully by March 1984 when the unit was brought into commercial
operation ahead of schedule and celebrated as a "labour victory".
Under pressure, the director of the Chernobyl station Viktor
Bryukhanov signed an acceptance document on the last day of 1983, in
order to declare that works planned for that year had been fulfilled.
Had he not done so, thousands of workers, engineers and his own
superiors would have lost bonuses, awards and other extras. Records
were falsified to hide this fact.[12]
The Chernobyl power plant had been in operation for two years without
this important safety feature. The station managers must have wished
to correct this at the first opportunity. This could explain why they
were so determined to carry out the test, even when serious problems
arose, and why the requisite approval for the test was not sought from
the Soviet nuclear oversight regulatory body.[13]
For the experiment, the reactor would be set at a low power setting
and the steam turbine run up to full speed, at which point the steam
supply would be closed off and the turbines allowed to freewheel, as
the results were recorded.
Conditions prior to the accident
Conditions to run the test were prepared during the daytime of 25
April 1986. The day shift had been instructed in advance about the
test and was familiar with procedures. A special team of electrical
engineers was present to test the new voltage regulating system.[14]
As planned, the reactor's power output had been gradually reduced to
50%. Then a regional power station unexpectedly went offline. The Kiev
grid controller requested that the further reduction of output be
postponed, as power was consequently needed to satisfy the evening
peak demand. The Chernobyl plant director agreed and postponed the
test to comply.
At 11:04 p.m., the Kiev grid controller allowed the reactor shut-down
to resume. This delay had serious consequences: the day shift had long
since departed, the evening shift was also preparing to leave, and the
night shift wouldn't take over until 12:00 midnight, well into the
experiment. The special team of electrical engineers must have been
exhausted from the long wait; according to plan, the test should have
been finalized during the daytime and the night shift would only have
to maintain basic cooling systems in a plant otherwise shut down,
though the night shift was not prepared to carry out the experiment.
Alexander Akimov was chief of the night shift and Leonid Toptunov was
the operator responsible for the reactor's operational regime,
including the movement of the control rods. Toptunov was a young
engineer who had only worked independently as a senior engineer for
about three months.[15]
In Valeri Legasov's posthumous article, he maintains that the
operators did not know what the test was about:
I have in my safe a transcript of the operators' telephone
conversations on the eve of the accident. Reading the transcript makes
one's flesh creep. One operator rings another and asks: What shall I
do? In the programme there are instructions of what to do, and then a
lot of things are crossed out. His interlocutor thought for a while
and then replied: Follow the crossed out instructions.[16]
The test plan called for the power output of reactor 4 to be reduced
from its nominal 3200 MW thermal to 700–1000 MW thermal.[17] For
unknown reasons, Toptunov committed an error and inserted the control
rods too far, causing the reactor to a near shut down. The exact
circumstances will probably never be known as both Akimov and Toptunov
died from radiation sickness.
The reactor power dropped to 30 MW thermal (10 MW electrical) — almost
complete shut down level and approximately 5 percent of what was
expected. At this low power output a phenomenon called xenon
poisoning, by which high levels of xenon-135 absorb neutrons and thus
inhibit nuclear reaction, became predominant.[18].
At this low power output it was impossible to carry out the test. The
operators seem to have been unaware of the xenon poisoning, perhaps
believing that the rapid fall in output was due to a malfunction in
one of the automatic power regulators. To increase power, control rods
were pulled out of the reactor core, beyond the correct position for
normal operations, and also beyond what is allowed under safety
regulations. To do this, staff had to use manual controls to override
the automatic system.[19]
Slowly, the reactor's power only increased to 200 MW, less than a
third of the minimum required for the experiment, yet the experiment
was continued. As part of the test plan, at 1:05 a.m. on 26 April
extra water pumps were activated, increasing the water flow. The flow
exceeded the safe limit at 1:19 a.m. The extra water lowered the core
temperature and reduced steam voids. However, since water also absorbs
neutrons (and the higher density of liquid water makes it a better
absorber than steam), this decreased reactor power further. This
prompted the operators to remove the manual control rods.
This produced an extremely unstable condition with nearly all of the
control rods removed; a setup for a run-away reaction. The only thing
holding the reactor at such a low power level was the high levels of
neutron-absorbing xenon. The increased water flow led to a fall in
steam production and other changes in the operating parameters. At
this point the automatic control system should have shut the reactor
down. To avoid this, the operators had disabled the shut down system.
[19]
Fatal experiment
Aerial view of the damaged core. Roof of the turbine hall is damaged
(image center). Roof of the adjacent reactor 3 (image lower left)
shows minor fire damage.
At 1:23:04 a.m. the experiment began. The extremely unstable condition
of the reactor was not known to the reactor crew, and the steam to the
turbines was shut off. As the momentum of the turbine generator drove
the water pumps, the water flow rate decreased, leading to the
formation of steam voids. The control rods that were removed earlier
were never fully removed and were still partially in the reactor,
preventing the heat from reaching the cooling water. The great rise in
temperature resulted in a massive steam build up and, due to the fact
that the RBMK type reactors are largely positive void coefficient, the
power within the reactor only increased. As the reactor power
increased, so did the neutron generation. Soon it exceeded what could
be absorbed by the xenon poisoning, starting a dangerous cascade. With
the manual and automatic neutron absorbing control rods removed,
nothing prevented a runaway reaction.
With reactor output rapidly increasing, the operators pressed the AZ-5
("Rapid Emergency Defense 5") button at 1:23:40, which ordered a
"SCRAM" — a shutdown of the reactor, fully inserting all control rods,
including the manual control rods that had been incautiously withdrawn
earlier. It is unclear whether it was done as an emergency measure, or
simply as a routine method of shutting down the reactor upon the
completion of an experiment (the reactor was scheduled to be shut down
for routine maintenance). The SCRAM may have been ordered as a
response to the unexpected rapid power increase; on the other hand,
Dyatlov writes in his book:
Prior to 01:23:40, systems of centralized control … didn't
register any parameter changes that could justify the SCRAM.
Commission … gathered and analyzed large amount of materials and, as
stated in its report, failed to determine the reason why the SCRAM was
ordered. There was no need to look for the reason. The reactor was
simply being shut down upon the completion of the experiment.[20]
The control rod insertion mechanism operated at relatively slow speed
(0.4 m/s) taking 18–20 seconds to travel the full approximately 7
meter core-length (height). A bigger problem was a flawed graphite-tip
control rod design, which initially displaced coolant, before the
reaction was slowed. In this way, the SCRAM actually increased the
reaction rate. At this point a massive energy spike occurred, and the
core overheated. Some of the fuel rods fractured, blocking the control
rod columns, and causing the control rods to become stuck after being
inserted only one-third of the way. Within three seconds the reactor
output rose above 530 MW.[21] By 1:23:47 (seven seconds after the AZ-5
button was pressed) the reactor jumped to around 30 GW thermal, ten
times the normal operational output. The rapid increase in steam
pressure destroyed fuel channels and ruptured the large diameter
cooling water pipes. Fuel rods began to melt and reached the cooling
water in the flooded basement.[22]
At 1:24, 20 seconds after the SCRAM was ordered, the first steam
explosion took place. It blew the 2,000 ton lid off of the reactor,
damaged the top of the reactor hall, and ejected fragments of
material. This ruptured further fuel channels, lifted control rods and
sheared off horizontal pipes. A second, more powerful explosion
occurred about two or three seconds after the first:
Lumps of graphite moderator ejected from the core. The largest lump
shows an intact control rod channel.
The second explosion was caused by the hydrogen which had been
produced either by the overheated steam-zirconium reaction or by the
reaction of red-hot graphite with steam that produce hydrogen and
oxygen[23]. According to observers outside Unit 4, burning lumps of
material and sparks shot into the air above the reactor. Some of them
fell onto the roof of the machine hall and started a fire. About 25
per cent of the red-hot graphite blocks and overheated material from
the fuel channels was ejected. ... Parts of the graphite blocks and
fuel channels were blown out of the reactor building. ... As a result
of the damage to the building an airflow through the core was
established by the high temperature of the core. The air ignited the
hot graphite and started a graphite fire.[24]
The graphite fire greatly contributed to the spread of radioactive
material and the contamination of outlying areas.[25]
Contrary to safety regulations, a combustible material (bitumen) had
been used in the construction of the roof of the reactor building and
the turbine hall. Ejected material had ignited at least five fires on
the roof of the (still operating) adjacent reactor 3. It was
imperative to put those fires out and protect the cooling systems of
reactor 3.[26] Inside reactor 3, the chief of the night shift, Yuri
Bagdasarov, wanted to shut down the reactor immediately, but chief
engineer Nikolai Fomin would not allow this. The operators were given
respirators and potassium iodide tablets and told to continue working.
At 05:00, however, Bagdasarov made his own decision to stop the
reactor, leaving only those operators there who had to work the
emergency cooling systems.[27]
Immediate crisis management
Radiation levels
The radiation levels in the worst-hit areas of the reactor building
have been estimated to be 5.6 röntgen per second (R/s) (0.056 Grays
per second, or Gy/s), which is equivalent to 20,000 röntgen per hour
(R/hr) (200 Gy per hour, or Gy/hr). A lethal dose is around 500
röntgen (5 Gy) over 5 hours, so in some areas, unprotected workers
received fatal doses within several minutes. However, a dosimeter
capable of measuring up to 1,000 R/s (10 Gy/s) was inaccessible due to
the explosion, and another one failed when turned on. All remaining
dosimeters had limits of 0.001 R/s (0.00001 Gy/s) and therefore read
"off scale". Thus, the reactor crew could ascertain only that the
radiation levels were somewhere above 0.001 R/s (3.6 R/hr, or 0.036 Gy/
hr), while the true levels were much higher in some areas.[28]
Because of the inaccurate low readings, the reactor crew chief
Alexander Akimov assumed that the reactor was intact. The evidence of
pieces of graphite and reactor fuel lying around the building was
ignored, and the readings of another dosimeter brought in by 4:30 a.m.
were dismissed under the assumption that the new dosimeter must have
been defective.[28] Akimov stayed with his crew in the reactor
building until morning, trying to pump water into the reactor. None of
them wore any protective gear. Most of them, including Akimov, died
from radiation exposure within three weeks.[citation needed]
Fire containment
Firefighter Leonid Telyatnikov, being decorated for bravery
Shortly after the accident, firefighters arrived to try to extinguish
the fires. The first one to the scene was a Chernobyl Power Station
firefighter brigade under the command of Lieutenant Vladimir Pravik,
who died on 9 May 1986 of acute radiation sickness. They were not told
how dangerously radioactive the smoke and the debris were, and may not
even have known that the accident was anything more than a regular
electrical fire: "We didn't know it was the reactor. No one had told
us."[29]
Grigorii Khmel, the driver of one of the fire-engines, later described
what happened:
We arrived there at 10 or 15 minutes to two in the morning ... We
saw graphite scattered about. Misha asked: What is graphite? I kicked
it away. But one of the fighters on the other truck picked it up. It's
hot, he said. The pieces of graphite were of different sizes, some
big, some small enough to pick up ...
We didn't know much about radiation. Even those who worked there
had no idea. There was no water left in the trucks. Misha filled the
cistern and we aimed the water at the top. Then those boys who died
went up to the roof - Vashchik Kolya and others, and Volodya
Pravik ... They went up the ladder ... and I never saw them again.[30]
The immediate priority was to extinguish fires on the roof of the
station and the area around the building containing Reactor No. 4 in
order to protect No. 3 and keep its core cooling systems intact. The
fires were extinguished by 5 a.m., but many firefighters received high
doses of radiation. The fire inside Reactor No. 4 continued to burn
until 10 May 1986; it is possible that well over half of the graphite
burned out.[9] The fire was extinguished by a combined effort of
helicopters dropping over 5,000 tonnes of materials like sand, lead,
clay and boron onto the burning reactor and injection of liquid
nitrogen. Ukranian filmmaker Vladimir Shevchenko captured film footage
of a Mi-8 helicopter as it lost its bearings while dropping its load
and got its rotors tangled in the gibbets of a nearby construction
crane, causing the wrecked copter to fall into the damaged reactor
building and kill its two-man crew.
From eyewitness accounts of the firefighters involved before they died
(as reported on the CBC television series Witness), one described his
experience of the radiation as "tasting like metal", and feeling a
sensation similar to that of pins and needles all over his face. (This
is similar to the description given by Louis Slotin, a Manhattan
Project physicist who died days after a fatal radiation overdose from
a criticality accident.)
The explosion and fire threw particles of the nuclear fuel and also
far more dangerous radioactive elements like caesium-137, iodine-131,
strontium-90 and other radionuclides into the air: the residents of
the surrounding area observed the radioactive cloud on the night of
the explosion.
Evacuation of Pripyat
Evacuation of Pripyat
After radiation levels set off alarms at the Forsmark Nuclear Power
Plant in Sweden,[31] the Soviet Union did admit that an accident had
occurred, but still tried to cover up the scale of the disaster. In
order to evacuate the city of Pripyat, the following warning message
was reported on local radio, "An accident has occurred at the
Chernobyl Nuclear Power Plant. One of the atomic reactors has been
damaged. Aid will be given to those affected and a committee of
government inquiry has been set up." This message gave the impression
that any damage and radiation was localized, although it was not.
The government committee formed to investigate the accident, led by
Valeri Legasov, arrived at Chernobyl in the evening of 26 April. By
that time two people were dead and 52 were hospitalized. During the
night of 26 April / 27 April — more than 24 hours after the explosion
— the committee, faced with ample evidence of extremely high levels of
radiation and a number of cases of radiation exposure, had to
acknowledge the destruction of the reactor and order the evacuation of
the nearby city of Pripyat.
The evacuation began at 14:00, 27 April. In order to reduce baggage
the residents were told that the evacuation would be temporary,
lasting approximately three days. As a result, Pripyat still contains
personal belongings.
Steam explosion risk
Lava flows formed by fuel-containing mass in the basement of the
plant. Lava flow (1). Concrete (2). Steam pipe (3). Electrical
equipment (4)
There was a bubbler pool beneath the reactor. It served as a large
water reservoir from the emergency cooling pumps and as a pressure
suppression system capable of condensing steam from a (small) broken
steam pipe. The pool and the basement were flooded due to ruptured
cooling water pipes and accumulated fire water. It now constituted a
serious steam explosion risk. The smouldering fuel and other material
above were starting to burn their way through the reactor floor,
mixing with molten concrete that had lined the reactor, and creating a
radioactive semi-liquid material comparable to lava. If this mixture
had melted through the floor into the pool of water, it would create a
massive steam explosion which would eject more radioactive material
from the reactor. It became an immediate priority to drain the pool.
[32]
The bubbler pool could be drained by opening its sluice gates.
Volunteers in diving suits entered the radioactive water and managed
to open the gates. These were engineers Alexei Ananenko (who knew
where the valves were) and Valeri Bezpalov, accompanied by a third
man, Boris Baranov, who provided them with light from a lamp, though
this lamp failed, leaving them to find the valves by feeling their way
along a pipe. None of the three ever returned to the surface and it is
thought one of them died before reaching the gates. [33] Fire brigade
pumps were then used to drain the basement. The operation was only
completed by 8 May, after having pumped out 20,000 tonnes of highly
radioactive water.
With the bubbler pool gone, a meltdown was less likely to produce a
powerful steam explosion. The molten core would now have to reach the
water table below the reactor. To reduce the likelihood of this it was
decided to freeze the earth beneath the reactor; this would also
stabilize the foundations. Using oil drilling equipment, injection of
liquid nitrogen began on 4 May. It was estimated that 25 tonnes of
liquid nitrogen per day would be required to keep the soil frozen at
-100 °C.[34]
Debris removal
The worst of the radioactive debris was collected inside what was left
of the reactor, much of it shoveled in by liquidators wearing heavy
protective gear (dubbed "bio-robots" by the military); these workers
could only spend a maximum of 40 seconds at a time working on the
rooftops of the surrounding buildings due to the extremely high doses
of radiation given off by the blocks of graphite and other debris. The
reactor itself was covered with bags containing sand, lead and boric
acid thrown off helicopters (some 5,000 metric tonnes during the week
following the accident). By December 1986 a large concrete sarcophagus
had been erected, to seal off the reactor and its contents.[35]
Many of the vehicles used by the "liquidators" remain parked in a
field in the Chernobyl area to this day, most giving off doses of
10-30 R/hr (0.1-0.3 Gy/hr) over 20 years after the disaster.[36]
Causes of the disaster
There were two official explanations of the accident: the first,
'flawed operators explanation', was published in August 1986 and
effectively placed the blame on the power plant operators. There is no
question that the operators violated the reactor's design
specifications, and were seemingly ignorant of the safety requirements
needed by the RBMK design. This was probably due to their lack of
knowledge of reactor physics and engineering, as well as lack of
experience and training. At the time of the accident, the reactor was
being operated with many key safety systems shut off, most notably the
Emergency Core Cooling System (ECCS).[37]
In his book, "The Truth about Chernobyl," Grigori Medvedev (who was
Deputy Director of the main industrial department in the Ministry of
Energy that oversaw the construction of nuclear power plants at the
time of the accident, and who also had been Deputy Chief Engineer for
the Chernobyl No. 1 reactor in the 1970s) lists seven different
serious violations of the reactor's operational safety specifications
that were committed during the preparation and conduct of the fateful
test.[38] He blames the chief engineer of the Chernobyl No. 4 reactor,
N.M. Fomin, saying "...only a man with no understanding of the
processes of neutron physics inside a nuclear reactor could possibly
have switched off the emergency core cooling system, which could in
the critical seconds have prevented the blast by sharply reducing
steam content in the core."[37]
Several procedural irregularities also helped to make the accident
possible. One was insufficient communication between the safety
officers and the operators in charge of the experiment being run that
night. The reactor operators disabled every safety system down to the
generators, which the test was really about. The main process
computer, SKALA, was running in such a way that the main control
computer could not shut down the reactor or even reduce power.
Normally the reactor would have started to insert all of the control
rods. The computer would have also started the "Emergency Core
Protection System" that introduces 24 control rods into the active
zone within 2.5 seconds, which is still slow by 1986 standards. All
control was transferred from the process computer to the human
operators.
The second 'flawed design explanation' was discussed by Valeri Legasov
and published in 1991, attributing the accident to flaws in the RBMK
reactor design, specifically the control rods.
* The reactor had a dangerously large positive void coefficient.
The void coefficient is a measurement of how the reactor responds to
increased steam formation in the water coolant. Most other reactor
designs produce less energy as they get hotter, because if the coolant
contains steam bubbles, fewer neutrons are slowed down. Faster
neutrons are less likely to split uranium atoms, so the reactor
produces less power. Chernobyl's RBMK reactor, however, used solid
graphite as a neutron moderator to slow down the neutrons, and neutron-
absorbing light water to cool the core. Thus neutrons are slowed down
even if steam bubbles form in the water. Furthermore, because steam
absorbs neutrons much less readily than water, increasing an RBMK
reactor's temperature means that more neutrons are able to split
uranium atoms, increasing the reactor's power output. This makes the
RBMK design very unstable at low power levels, and prone to suddenly
increasing energy production to dangerous level if the temperature
rises. This was counter-intuitive and unknown to the crew.
* A more significant flaw was in the design of the control rods
that are inserted into the reactor to slow down the reaction. In the
RBMK reactor design, the control rod end tips were made of graphite
and the extenders (the end areas of the control rods above the end
tips, measuring 1-metre (3 ft) in length) were hollow and filled with
water, while the rest of the rod — the truly functional part which
absorbs the neutrons and thereby halts the reaction — was made of
boron carbide. With this design, when the rods are initially inserted
into the reactor, the graphite ends displace some coolant. This
greatly increases the rate of the fission reaction, since graphite is
a more potent neutron moderator (a material that enables a nuclear
reaction) and also absorbs far fewer neutrons than the boiling light
water. Thus for the first few seconds of control rod activation,
reactor power output is increased, rather than reduced as desired.
This behavior is counter-intuitive and was not known to the reactor
operators.
* The water channels run through the core vertically, meaning that
the water's temperature increases as it moves up and thus creates a
temperature gradient in the core. This effect is exacerbated if the
top portion turns completely to steam, since the topmost part of the
core is no longer being properly cooled and reactivity greatly
increases. (By contrast, the CANDU reactor's water channels run
through the core horizontally, with water flowing in opposite
directions among adjacent channels. Hence, the core has a much more
even temperature distribution.)
* To reduce costs, and because of its large size, the reactor had
been constructed without any secure containment. This allowed the
radioactive contaminants to freely escape into the atmosphere after
the steam explosion burst the primary pressure vessel.
* The reactor also had been running for over one year, and was
storing fission byproducts; these byproducts pushed the reactor
towards disaster.
* As the reactor heated up, design flaws caused the reactor vessel
to warp and break up, making further insertion of control rods
impossible as the heat deformed them.
Both commissions were heavily lobbied by different groups, including
the reactor's designers, power plant personnel, and by the Soviet and
Ukrainian governments. The IAEA's 1986 analysis attributed the main
cause of the accident to the operators' actions. But in January 1993,
the IAEA issued a revised analysis, attributing the main cause to the
reactor's design.[39]
Another contributing factor was that the operators were not informed
about problems with the reactor. According to Anatoliy Dyatlov, the
designers knew that the reactor was dangerous in some conditions but
intentionally concealed this information.[citation needed] In
addition, the plant's management was largely composed of non-RBMK-
qualified personnel: the director, V.P. Bryukhanov, had experience and
training in a coal-fired power plant. His chief engineer, Nikolai
Fomin, also came from a conventional power plant. Dyatlov, deputy
chief engineer of reactors 3 and 4, had only "some experience with
small nuclear reactors", namely smaller versions of the VVER nuclear
reactors that were designed for the Soviet Navy's nuclear submarines.
[citation needed]
Many or all of these factors probably contributed to the disaster. A
potentially unstable reactor design, shoddy and inadequate safety
features, poorly-trained or incompetent operators, and a lack of
containment building all worked together on that horrific April night
in the Byelorussian-Ukrainian Woodlands.[40] The underlying
vulnerabilities and flaws in the Soviet nuclear industry which set the
stage for the tragedy had been developing for as much as 35 years.[41]
Grigori Medvedev's book, "The Truth about Chernobyl" tells how the
secretive, authoritarian Soviet bureaucracy (which valued party
loyalty over competence) kept promoting incompetent personnel and
choosing cheapness over safety until it engineered this terrible
catastrophe.
The effects of the disaster
Main article: Chernobyl disaster effects
International spread of radioactivity
Moscow's Mitino cemetery Chernobyl monument
The nuclear meltdown produced a radioactive cloud that floated not
over just the modern states of Russia, Belarus, Ukraine and Moldova,
but also Turkish Thrace, the Southern coast of the Black Sea,
Macedonia, Serbia, Croatia, Bosnia-Herzegovina, Bulgaria, Greece,
Romania, Lithuania, Estonia, Latvia, Finland, Denmark, Norway, Sweden,
Austria, Hungary, the Czech Republic and the Slovak Republic, The
Netherlands, Belgium, Slovenia, Poland, Switzerland, Germany,
Luxembourg, Italy, Ireland, France (including Corsica[42]) the United
Kingdom and the Isle of Man.[43][44]
The initial evidence that a major exhaust of radioactive material was
affecting other countries came not from Soviet sources, but from
Sweden, where on 27 April workers at the Forsmark Nuclear Power Plant
(approximately 1,100 km (680 mi) from the Chernobyl site) were found
to have radioactive particles on their clothes.[45] It was Sweden's
search for the source of radioactivity, after they had determined
there was no leak at the Swedish plant, which led to the first hint of
a serious nuclear problem in the western Soviet Union. The rise of
radiation levels had at that time already been measured in Finland,
but a civil service strike delayed the response and publication.[46]
Contamination from the Chernobyl accident was scattered irregularly
depending on weather conditions. Reports from Soviet and Western
scientists indicate that Belarus received about 60% of the
contamination that fell on the former Soviet Union. However, the 2006
TORCH report stated that half of the volatile particles had landed
outside Ukraine, Belarus and Russia. A large area in Russia south of
Bryansk was also contaminated, as were parts of northwestern Ukraine.
Studies in countries around the area say that over one million people
could have been affected by radiation.[47]
Recently published data of a long-term monitoring programme (The Korma-
Report[48]) show a decrease of internal radiation exposure of the
inhabitants of a region in Belarus close to Gomel. Resettlement may
even be possible in prohibited areas provided that people comply with
appropriate dietary rules.
In Western Europe, measures were taken including seemingly arbitrary
regulations pertaining to the legality of importation of certain foods
but not others. In France some officials stated that the Chernobyl
accident had no adverse effects.
Radioactive release (source term)
Like many other releases of radioactivity into the environment, the
Chernobyl release was controlled by the physical and chemical
properties of the radioactive elements in its core. While plutonium is
often perceived as particularly dangerous nuclear fuel by the general
population, its effects are almost eclipsed by those of its fission
products. Particularly dangerous are highly radioactive compounds that
accumulate in the food chain, such as some isotopes of iodine and
strontium.
The external gamma dose for a person in the open near the Chernobyl
site.
The contributions by the various isotopes to the dose (in air) in the
contaminated area soon after the accident.
Two reports on the release of radioisotopes from the site were made
available, one by the OSTI, and a more detailed report by OECD, both
in 1998.[49][50] At different times after the accident, different
isotopes were responsible for the majority of the external dose. The
dose that was calculated is that received from external gamma
irradiation for a person standing in the open. The dose to a person in
a shelter or the internal dose is harder to estimate.
The release of the radioisotopes from the nuclear fuel was largely
controlled by their boiling points, and the majority of the
radioactivity present in the core was retained in the reactor.
* All of the noble gases, including krypton and xenon, contained
within the reactor were released immediately into the atmosphere by
the first steam explosion.
* About 55% of the radioactive iodine in the reactor was released,
as a mixture of vapor, solid particles and as organic iodine
compounds.
* Caesium and tellurium were released in aerosol form.
Two sizes of particles were released: small particles of 0.3 to 1.5
micrometers (aerodynamic diameter) and large particles of 10
micrometers. The large particles contained about 80% to 90% of the
released nonvolatile radioisotopes zirconium-95, niobium-95,
lanthanum-140, cerium-144 and the transuranic elements, including
neptunium, plutonium and the minor actinides, embedded in a uranium
oxide matrix.
Health of plant workers
A monument in Chisinau, Moldova
In the aftermath of the accident, 237 people suffered from acute
radiation sickness, of whom 31 died within the first three months.[51]
[52] Most of these were fire and rescue workers trying to bring the
accident under control, who were not fully aware of how dangerous the
radiation exposure (from the smoke) was (for a discussion of the more
important isotopes in fallout, see fission product). 135,000 people
were evacuated from the area, including 50,000 from Pripyat.[citation
needed]
Residual radioactivity in the environment
Rivers, lakes and reservoirs
The Chernobyl nuclear power plant lies next to the Pripyat River which
feeds into the Dnieper River reservoir system, one of the largest
surface water systems in Europe. The radioactive contamination of
aquatic systems therefore became a major issue in the immediate
aftermath of the accident.[53] In the most affected areas of Ukraine,
levels of radioactivity (particularly radioiodine: I-131,
radiocaesium: Cs-137 and radiostrontium: Sr-90) in drinking water
caused concern during the weeks and months after the accident. After
this initial period however, radioactivity in rivers and reservoirs
was generally below guideline limits for safe drinking water.[53]
Bio-accumulation of radioactivity in fish[54] resulted in
concentrations (both in western Europe and in the former Soviet Union)
that in many cases were significantly above guideline maximum levels
for consumption.[53] Guideline maximum levels for radiocaesium in fish
vary from country to country but are approximately 1,000 Bq/kg in the
European Union.[55] In the Kiev Reservoir in Ukraine, activity
concentrations in fish were several thousand Bq/kg during the years
after the accident.[54] In small "closed" lakes in Belarus and the
Bryansk region of Russia, activity concentrations in a number of fish
species varied from 0.1 to 60 kBq/kg during the period 1990–92.[56]
The contamination of fish caused concern in the short term (months)
for parts of the UK and Germany and in the long term (years-decades)
in the Chernobyl affected areas of Ukraine, Belarus and Russia as well
as in parts of Scandinavia.[53]
Groundwater
Map of radiation levels in 1996 around Chernobyl.
Groundwater was not badly affected by the Chernobyl accident since
radionuclides with short half-lives decayed away a long time before
they could affect groundwater supplies, and longer-lived radionuclides
such as radiocaesium and radiostrontium were adsorbed to surface soils
before they could transfer to groundwaters.[57] Significant transfers
of radionuclides to groundwaters have occurred from waste disposal
sites in the 30 km (19 mi) exclusion zone around Chernobyl. Although
there is a potential for off-site (i.e. out of the 30 km (19 mi)
exclusion zone) transfer of radionuclides from these disposal sites,
the IAEA Chernobyl Report[57] argues that this is not significant in
comparison to current levels of washout of surface-deposited
radioactivity.
Flora and fauna
After the disaster, four square kilometres of pine forest in the
immediate vicinity of the reactor turned ginger brown and died,
earning the name of the "Red Forest".[58] Some animals in the worst-
hit areas also died or stopped reproducing. Most domestic animals were
evacuated from the exclusion zone, but horses left on an island in the
Pripyat River 6 km (4 mi) from the power plant died when their thyroid
glands were destroyed by radiation doses of 150–200 Sv.[59] Some
cattle on the same island died and those that survived were stunted
because of thyroid damage. The next generation appeared to be normal.
[59]
In the years since the disaster, the exclusion zone abandoned by
humans has become a haven for wildlife, with nature reserves declared
(Belarus) or proposed (Ukraine) for the area. Many species of wild
animals and birds, which were not seen in the area prior to the
disaster, are now plentiful due to the absence of humans.[58]
A robot sent into the reactor itself has returned with samples of
black, melanin-rich fungi that are growing on the reactor's walls.[60]
Chernobyl after the disaster
The Prypiat Ferris wheel as seen from inside the town's Palace of
Culture.
Following the accident, questions arose about the future of the plant
and its eventual fate. All work on the unfinished reactors 5 and 6 was
halted three years later. However, the trouble at the Chernobyl plant
did not end with the disaster in reactor 4. The damaged reactor was
sealed off and 200 metres (660 ft) of concrete was placed between the
disaster site and the operational buildings. The Ukrainian government
continued to let the three remaining reactors operate because of an
energy shortage in the country. A fire broke out in the turbine
building of reactor 2 in 1991;[61] the authorities subsequently
declared the reactor damaged beyond repair and had it taken offline.
Reactor 1 was decommissioned in November 1996 as part of a deal
between the Ukrainian government and international organizations such
as the IAEA to end operations at the plant. On 15 December 2000, then-
President Leonid Kuchma personally turned off Reactor 3 in an official
ceremony, effectively shutting down the entire plant[62] transforming
the Chernobyl plant from energy producer to energy consumer.
Chernobyl today
Monument in Rivne, Ukraine
The Chernobyl reactor is now enclosed in a large concrete sarcophagus
which was built quickly to allow continuing operation of the other
reactors at the plant.[63] However, the structure is not strong or
durable. Some major work on the sarcophagus was carried out in 1998
and 1999. Some 200 tons of highly radioactive material remains deep
within it, and this poses an environmental hazard until it is better
contained.
A New Safe Confinement structure will be built by the end of 2011, and
then will be put into place on rails. It is to be a metal arch 105
meters high and spanning 257 metres, to cover both unit 4 and the
hastily built 1986 structure. The Chernobyl Shelter Fund, set up in
1997, has received €810 million from international donors and projects
to cover this project and previous work. It and the Nuclear Safety
Account, also applied to Chernobyl decommissioning, are managed by the
European Bank for Reconstruction and Development (EBRD).[citation
needed]
As of 2006, some fuel at units 1 to 3 remained in the reactors, most
of which is in each unit's cooling pond, as well as some material in a
small interim spent fuel storage facility pond (ISF-1).
In 1999 a contract was signed for construction of a radioactive waste
management facility to store 25,000 used fuel assemblies from units 1–
3 and other operational wastes, as well as material from
decommissioning units 1–3 (which will be the first RBMK units
decommissioned anywhere). The contract included a processing facility,
able to cut the RBMK fuel assemblies and to put the material in
canisters, which will be filled with inert gas and welded shut. They
will then be transported to the dry storage vaults in which the fuel
containers would be enclosed for up to 100 years. This facility,
treating 2500 fuel assemblies per year, would be the first of its kind
for RBMK fuel. However, after a significant part of the storage
structures had been built, technical deficiencies in the concept
emerged, and the contract was terminated in 2007. The interim spent
fuel storage facility (ISF-2) will now be completed by others by mid
2013.[citation needed]
Another contract has been let for a Liquid radioactive Waste Treatment
Plant, to handle some 35,000 cubic meters of low- and intermediate-
level liquid wastes at the site. This will need to be solidified and
eventually buried along with solid wastes on site.[citation needed]
In January 2008 Ukrainian government announced a 4-stage
decommissioning plan which incorporates the above waste activities and
progresses towards a cleared site.[47]
Lava-like Fuel Containing Materials (FCMs)
The radioactivity levels of different isotopes in the FCM, as back-
calculated by Russian workers to April 1986
According to official estimates, about 95% of the fuel (about 180
tonnes) in the reactor at the time of the accident remains inside the
shelter, with a total radioactivity of nearly 18 million curies (670
PBq). The radioactive material consists of core fragments, dust, and
lava-like "fuel-containing materials" (FCM) that flowed through the
wrecked reactor building before hardening into a ceramic form.
Three different lavas are present in the basement of the reactor
building; black, brown and a porous ceramic. They are silicate glasses
with inclusions of other materials present within them. The porous
lava is brown lava which had dropped into water thus being cooled
rapidly.
Degradation of the lava
It is unclear how long the ceramic form will retard the release of
radioactivity. From 1997 to 2002 a series of papers were published
which suggested that the self irradiation of the lava would convert
all 1,200 tons into a submicrometre and mobile powder within a few
weeks.[64] But it has been reported that it is likely that the
degradation of the lava is to be a slow and gradual process rather
than a sudden rapid process.[65] The same paper states that the loss
of uranium from the wrecked reactor is only 10 kg (22 lb) per year.
This low rate of uranium leaching suggests that the lava is resisting
its environment. The paper also states that when the shelter is
improved, the leaching rate of the lava will decrease.
Some of the surfaces of the lava flows have started to show new
uranium minerals such as Na4(UO2)(CO3)3 and uranyl carbonate. However
the level of radioactivity is such that during one hundred years the
self irradiation of the lava (2 × 1016 α decays per gram and 2 to 5 ×
105 Gy of β or γ) will fall short of the level of self irradiation
which is required to greatly change the properties of glass (1018 α
decays per gram and 108 to 109 Gy of β or γ). Also the rate of
dissolution of the lava in water is very low (10–7 g-cm–2 day–1)
suggesting that the lava is unlikely to dissolve in water.[65]
Possible consequences of further collapse of the Sarcophagus
The Sarcophagus, the concrete block surrounding reactor #4
The protective box which was placed over the wrecked reactor was named
object "Shelter" by the Soviet government, but the media and the
public know it as the sarcophagus.
The present shelter is constructed atop the ruins of the reactor
building. The two "Mammoth Beams" that support the roof of the shelter
are resting partly upon the structurally unsound west wall of the
reactor building that was damaged by the accident. The western end of
the shelter roof was supported by a wall (at a point designated axis
50). This wall is reinforced concrete, which was cracked by the
accident. In December 2006 the Designed Stabilisation Steel Structure
(DSSS) was extended until 50% of the roof load (circa 400 tons) was
transferred from the axis-50 wall to the DSSS. The DSSS is a yellow
steel object which has been placed next to the wrecked reactor; it is
63 metres (207 ft) tall and has a series of cantilevers which extend
through the western buttress wall, and intended to stabilise the
sarcophagus.[66] This was done because if the wall of the reactor
building or the roof of the shelter were to collapse, then large
amounts of radioactive dust and particles would be released directly
into the atmosphere, resulting in a large new release of radioactivity
into the environment.
A further threat to the shelter is the concrete slab that formed the
"Upper Biological Shield" (UBS), situated above the reactor prior to
the accident. This concrete slab was thrown upwards by the explosion
in the reactor core and now rests at approximately 15° from vertical.
The position of the upper bioshield is considered inherently unsafe,
as only debris supports it in its nearly upright position. A collapse
of the bioshield would further exacerbate the dust conditions in the
shelter, possibly spreading some quantity of radioactive materials out
of the shelter, and could damage the shelter itself.
The sarcophagus was never designed to last for the 100 years needed to
contain the worst of the radioactivity found within the remains of
reactor 4. While present designs for a new shelter anticipate a
lifetime of up to 100 years, that time is minuscule compared to the
lifetime of the radioactive materials within the reactor. The
construction and maintenance of a permanent sarcophagus that can
completely contain the remains of reactor 4 will present a continuing
task to engineers for many generations to come. If the Chernobyl plant
were to collapse, a large release of radioactive dust would occur, but
it would likely be a one-time event.[dubious – discuss]
Grass and forest fires
Grass and forest fires have happened inside the contaminated zone,
releasing radioactive fallout into the atmosphere. In 1986 a series of
fires destroyed 23.36 km² (5,772 acres) of forest, and several other
fires have since burned within the 30 km (19 mi) zone. In early May
1992 a serious fire occurred which affected 5 km² (1,240 acres) of
land including 2.7 km² (670 acres) of forest. This resulted in a great
increase in the levels of caesium in airborne dust.[67][68][69][70]
It is known that fires can make the radioactivity mobile again.[71][67]
[72][73] In particular V.I. Yoschenko et al. reported on the
possibility of increased mobility of caesium, strontium, and plutonium
due to grass and forest fires.[74] As an experiment, fires were set
and the levels of the radioactivity in the air down wind of these
fires was measured.
Recovery process
The Chernobyl Shelter Fund was established in 1997 at the Denver G7
summit to finance the Shelter Implementation Plan (SIP). The plan
calls for transforming the site into an ecologically safe condition
through stabilization of the sarcophagus, followed by construction of
a New Safe Confinement (NSC). While original cost estimate for the SIP
was US$768 million, the 2006 estimate is $1.2 billion. The SIP is
being managed by a consortium of Bechtel, Battelle, and Electricité de
France, and conceptual design for the NSC consists of a movable arch,
constructed away from the shelter to avoid high radiation, to be slid
over the sarcophagus. The NSC is expected to be completed in 2012, and
will be the largest movable structure ever built.
Dimensions:
* Span: 270 m (886 ft)
* Height: 100 m (330 ft)
* Length: 150 m (492 ft)
The United Nations Development Programme has launched in 2003 a
specific project called the Chernobyl Recovery and Development
Programme (CRDP) for the recovery of the affected areas.[75] The
programme launched its activities based on the Human Consequences of
the Chernobyl Nuclear Accident report recommendations and has been
initiated in February 2002. The main goal of the CRDP’s activities is
supporting the Government of Ukraine to mitigate long-term social,
economic and ecological consequences of the Chernobyl catastrophe,
among others. CRDP works in the four most Chernobyl-affected areas in
Ukraine: Kyivska, Zhytomyrska, Chernihivska and Rivnenska.
The International Project on the Health Effects of the Chernobyl
Accident (IPEHCA) was created and received $20 million US, mainly from
Japan, in hopes of discovering the main cause of health problems due
to I131 radiation. These funds that were given to IPEHCA where divided
between Ukraine, Belarus, and Russia, the three main affected
countries, for further investigation of health effects. As corruption
played an important role of the former Soviet countries, most of the
foreign aid was given to Russia, and no positive outcome from this
money was ever shown.
Assessing the disaster's effects on human health
Main article: Chernobyl disaster effects
An international assessment of the health effects of the Chernobyl
accident is contained in a series of reports by the United Nations
Scientific Committee of the Effects of Atomic Radiation (UNSCEAR).[76]
UNSCEAR was set up as a collaboration between various UN bodies,
including the World Health Organisation, after the atomic bomb attacks
on Hiroshima and Nagasaki, to assess the long-term effects of
radiation on human health.
UNSCEAR has conducted 20 years of detailed scientific and
epidemiological research on the effects of the Chernobyl accident.
Apart from the 57 direct deaths in the accident itself, UNSCEAR
originally predicted up to 4,000 additional cancer cases due to the
accident,[5] however the latest UNSCEAR reports insinuate that these
estimates were overstated.[77] In addition, the IAEA states that there
has been no increase in the rate of birth defects or abnormalities, or
solid cancers (such as lung cancer) corroborating UNSCEAR's
assessments.[78]
Precisely, UNSCEAR states:
"Among the residents of Belarus, the Russian Federation and
Ukraine there had been, up to 2002, about 4,000 cases of thyroid
cancer reported in children and adolescents who were exposed at the
time of the accident, and more cases are to be expected during the
next decades. Notwithstanding problems associated with screening, many
of those cancers were most likely caused by radiation exposures
shortly after the accident. Apart from this increase, there is no
evidence of a major public health impact attributable to radiation
exposure 20 years after the accident. There is no scientific evidence
of increases in overall cancer incidence or mortality rates or in
rates of non-malignant disorders that could be related to radiation
exposure. The risk of leukaemia in the general population, one of the
main concerns owing to its short latency time, does not appear to be
elevated. Although those most highly exposed individuals are at an
increased risk of radiation-associated effects, the great majority of
the population is not likely to experience serious health consequences
as a result of radiation from the Chernobyl accident. Many other
health problems have been noted in the populations that are not
related to radiation exposure."[77]
Thyroid cancer is generally treatable.[79] The five year survival rate
of thyroid cancer is 96%, and 92% after 30 years, with proper
treatment.[80]
The Chernobyl Forum is a regular meeting of IAEA, other United Nations
organizations (FAO, UN-OCHA, UNDP, UNEP, UNSCEAR, WHO and The World
Bank) and the governments of Belarus, Russia, and Ukraine, which
issues regular scientific assessments of the evidence for health
effects of the Chernobyl accident.[81] The Chernobyl Forum concluded
that twenty-eight emergency workers died from acute radiation
syndrome, 15 patients died from thyroid cancer, and it roughly
estimated that cancers deaths caused by Chernobyl may reach a total of
about 4000 among the 600 000 people having received the greatest
exposures. It also concluded that a greater risk than the long-term
effects of radiation exposure, is the risk to mental health of
exaggerated fears about the effects of radiation:[82]
" ... The designation of the affected population as “victims”
rather than “survivors” has led them to perceive themselves as
helpless, weak and lacking control over their future. This, in turn,
has led either to over cautious behavior and exaggerated health
concerns, or to reckless conduct, such as consumption of mushrooms,
berries and game from areas still designated as highly contaminated,
overuse of alcohol and tobacco, and unprotected promiscuous sexual
activity."[83]
While it was commented by Fred Mettler that 20 years later:[84]
The population remains largely unsure of what the effects of
radiation actually are and retain a sense of foreboding. A number of
adolescents and young adults who have been exposed to modest or small
amounts of radiation feel that they are somehow fatally flawed and
there is no downside to using illicit drugs or having unprotected sex.
To reverse such attitudes and behaviors will likely take years
although some youth groups have begun programs that have promise.
In addition, disadvantaged children around Chernobyl suffer from
health problems which are not only to do with the Chernobyl accident,
but also with the desperately poor state of post-Soviet health systems.
[81]
Another study critical of the Chernobyl Forum report was commissioned
by Greenpeace, which is well known for its anti-nuclear positions. In
its report, Greenpeace alleges that "the most recently published
figures indicate that in Belarus, Russia and Ukraine alone the
accident could have resulted in an estimated 200,000 additional deaths
in the period between 1990 and 2004." However, the Greenpeace report
failed to discriminate between the general increase in cancer rates
that followed the dissolution of the USSR's health system and any
separate effects of the Chernobyl accident.[85]
Lastly, in its report Health Effects of Chernobyl, the German
affiliate of the International Physicians for the Prevention of
Nuclear War (IPPNW) argued that more than 10,000 people are today
affected by thyroid cancer and 50,000 cases are expected in the future.
[86] According to some commentators, both the Greenpeace and IPPNW
reports suffer from a lack of any genuine or original research and
failure to understand epidemiologic data.[77] This said, it is
important to bear in mind that many of the conclusions from reports
such as UNSCEAR remain disputed by other commentators and scientists
in the field.[87]
In the popular consciousness
Main article: Chernobyl in the popular consciousness
See also: Nuclear debate
The Chernobyl accident attracted a great deal of interest. Because of
the distrust that many people had in the Soviet authorities (people
both within and outside the USSR) a great deal of debate about the
situation at the site occurred in the first world during the early
days of the event. Due to defective intelligence based upon
photographs taken from space, it was thought that unit number three
had also suffered a dire accident.
A few authors claim that the official reports underestimate the scale
of the Chernobyl tragedy, counting only 30 victims;[88] some estimate
the Chernobyl radioactive fallout as hundreds of times that of the
atomic bomb dropped on Hiroshima, Japan,[89][90] counting millions of
exposed.
In general the public knew little about radioactivity and radiation
and as a result their degree of fear was increased. It was the case
that many professionals (such as the spokesman from the UK NRPB) were
mistrusted by journalists, who in turn encouraged the public to
mistrust them.[91]
It was noted[92] that different governments tried to set contamination
level limits which were stricter than the next country. In the dash to
be seen to be protecting the public from radioactive food, it was
often the case that the risk caused by the modification of the
nations' diet was greater and un-noticed.[citation needed]
In Italy, the fear of nuclear accidents was dramatically increased by
the Chernobyl accident: this reflected in the outcome of the 1987
referendum about the construction of new nuclear plants in Italy. As
effect of that referendum, Italy began phasing out its nuclear power
plants in 1988.
Commemoration of the disaster
Heavy Water: A film for Chernobyl was released by Seventh Art in 2006
to commemorate the disaster through poetry and first-hand accounts
[1]. The film secured the Cinequest Award as well as the Rhode Island
'best score' award [2] along with a screening at Tate Modern [3].
Chernobyl 20
This exhibit presents the stories of 20 people who have each been
affected by the disaster, and each person's account is written on a
panel. The 20 individuals whose stories are related in the exhibition
are from Belarus, France, Latvia, Russia, Sweden, Ukraine, and the
United Kingdom.
Developed by Danish photo-journalist Mads Eskesen, the exhibition is
prepared in multiple languages including in German, English, Danish,
Dutch, Russian and Ukrainian.
In Kyiv, Ukraine, the exhibition was launched at the "Chernobyl 20
Remembrance for the Future" conference on 23 April 2006. It was then
exhibited during 2006 in Australia, Denmark, the Netherlands,
Switzerland, Ukraine, the United Kingdom, and the United States.