The test
One of the tests incompletely carried out before the reactor becoming
operational was on the functioning of the turbine in the case of a defect.
[...read
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25 April (Friday)
13.05 hours (times are local times - Moscow times where similar
then) -Preparations for the turbine test begin. For this test, the plant's
capacity must be reduced and for this reason one turbine is turned off.
14.00 hours - The controller of the Ukraine electricity network
requests that the test be delayed. All electricity from Unit 4 is necessary.
It is not clear why it was not predictable beforehand that work would have
to continue all through Friday afternoon in order to achieve the production
planned for April.
16.00 hours - The day shift leaves. The members of this shift
have been given information about the test during the previous days, and
know about the entire procedure. A special team of electronic engineers
is present.
23.10 hours - Preparations for the test start again. The ten
hour delay has a large number of consequences. Firstly, the team of engineers
is tired. Secondly, during the test, the evening shift is replaced by the
night shift. This shift has fewer experienced operators, besides which
they were not prepared for the test. Achier Razachkov, - Yuri Tregub and
A. Uskov are the operators who were responsible for carrying out the test
earlier in the day: later in interviews they declared that test procedures
were only explained to the day and evening shifts. Yuri Tregub decides
to stay and help the night shift.
26 April (Saturday)
01.00 hours - During preparations for the test, the operators
have difficulty keeping the capacity of the nuclear plant stable. While
doing this they make six important mistakes.
1. The control rods which can stop the reactor are raised higher than
regulations permit. Operator Uskov of the day shift said later that he
would have done the same. He said: "We often don't see the need to follow
the instructions to the letter, because rules are often infringed all around
us." As well as this, he pointed to the fact that during training it was
repeated over and over again that "a nuclear power plant cannot explode".
Operator Kazachkov said: "We have often had fewer control rods than were
required, and nothing ever happened. No explosion, everything just went
on as normal."
2. The plant's capacity decreases to below the safe level. Because
of this the core becomes unstable. Preparations for the test should have
been stopped by now. It should have been obvious that all attention should
be given to measures for regaining the plant's stability.
3. In order to raise the capacity, an extra circulation pump is turned
on. Because of the strong cooling down, the pressure falls, thus reducing
the reactor's capacity rather than increasing it. Normally at this stage
the scram system should start working, but in order to still be able to
carry out the test, this system is turned off.
4. The automatic emergency shut-down system is turned off in order
to prevent the reactor stopping itself.
5. The systems to prevent the' water level decreasing too much and
the temperature of the fuel elements becoming too high are also turned
off.
6. Finally, the emergency cooling system is turned off to prevent it
working during the test.
1.23.04 hours - The real test now begins. The power plant's
capacity suddenly increases unexpectedly.
1.23.40 hours - Leonid Toptunov, responsible for the control
rods, presses a special button for an emergency shutdown. The test has
been going on for 36 seconds.
1.23.44 hours - The control rods start to descend, but shocks
can be felt. The operators see that the control rods have become stuck.
The fuel tubes have become deformed because of the large increase in the
steam pressure.
1.24.00 hours - The test has now been going on for 56 seconds.
Pressure in the reactor is now so high that the fuel elements burst and
small particles land in the cooling water. The cooling water turns into
steam and pressure in the tubes increases: they burst.
The 1000 tonne lid above the fuel elements is lifted: the first explosion.
The release of radiation starts. Air gets into the reactor. There is enough
oxygen to start a graphite fire. The metal of the fuel tubes reacts to
the water. This is a chemical reaction which produces hydrogen, and this
hydrogen explodes: the second explosion. Burning debris flies into the
air and lands on the roof of Chernobyl Unit 3. (There was barely any attention
paid to this hydrogen explosion in the Soviet report about the accident.
In studies commissioned by the US government, however, it was concluded
that the second explosion was of great significance, and that the original
explanation of the accident was incorrect. Richard Wilson of the Harvard
University in the US said this second explosion was a small nuclear explosion.)
The head of the night shift, Alexander Akinhov, and the engineer responsible
for industrial management, Anatoly Diatlov, do not believe that an accident
has taken place. When somebody claims the core has exploded, they send
out operators to examine the core. These people are killed by radiation.
On hearing the report that the reactor has been destroyed Akimov cries
out, "The reactor is OK, we have no problems."
Akimov and Diatlov, assisted by manager Bryukhanov and engineer N.Fomin,
keep ordering the operators to add more cooling water. They remain convinced
that there is nothing wrong. Akimov and Toptunov, who was responsible for
the control rods, both died of radiation illness. Diatlov and Fomin were
both sentenced to ten years imprisonment for infringement of the safety
regulations. However, at the end of 1990 they were both released.
Unit 4 of the Nuclear power plant at Chernobyl explodes. Debris flies into the air and lands on the roof of Unit 3 which is right next to the exploded Unit 4. The units share a communal machine turbine hall with a roof of bitumen, a flammable material. Thirty fires develop. The fact that the accident happens at night has one great advantage: in the daytime, 2000 people are working on the construction of Chernobyl Units 5 and 6. These people are now at home.
01.25 hours - The fire alarm rings at the local fire station.
Meanwhile more people are killed: The nuclear plant's fire fighters arrive
with three fire engines. The leader, Lieutenant Pravik, quickly realizes
that his team is too small and asks the fire brigades from Pripyat, the
town of Chernobyl and the entire area of Kiev for their assistance. Pravik
and his team climb onto the roof of the machine hail and start their attempts
to extinguish the fire. The fire brigade, from Pripyat arrives minutes
later and fights the fires in the reactor building. Pravik and several
firemen from Pripyat die later of radiation illness.
01.45 hours - New teams of fire fighters from the area arrive.
They know nothing about the danger of radiation, have no protective clothing
or dosimeters. One of the fire engine drivers, Grigory Khmel said later:
"We arrived at ten minutes to two in the morning. We saw graphite lying
everywhere. I kicked a bit of it. Another fireman picked up a piece and
said 'hot'. Neither of us had any idea of radiation. My colleagues Kolya,
Pravik and others all went up the ladder to the roof of the reactor. I
never saw them again."
02.15 hours - The Pripyat department of the Ministry of Home
Affairs calls a crisis meeting. It is decided to organize a road block
in order to prevent cars from entering or leaving the town. Police assistance
is requested. Thousands of police arrive; and, as with the fire fighters,
they have no knowledge of radiation, no dosimeters or protective clothing.
Later, in 1988, it is admitted that a total of 16,500 police were deployed.
Of those, 57 people developed chronic radiation illness, 1500 of them suffer
from chronic respiratory problems and 4000 suffer from other symptoms.
03.12 hours - An alarm signal goes off at the army headquarters
in the central area of the Soviet Union at 03.12 hours. General Pikalov
decides to send in troops to help. They arrive in Kiev at 14.00 hours.
These are the first people to arrive well prepared for their task. About
the same time, the responsible authorities such as the Energy Minister,
A. Mayorets, hear that an accident has occurred, but are led to believe
it is a small defect.
05.00 hours - In spite of the fires, Chernobyl Unit 3 is not
closed down until five o'clock am.
06.35 hours - No fewer than 37 fire brigades, with a total of
186 fire fighters, have been called in to extinguish all the fires; the
fire in the reactor could not actually be extinguished. The importance
of the deployment of these fire fighters cannot be emphasized enough. The
roof of Unit 3 caught fire immediately, which meant that this reactor could
have been seriously damaged as well. The nuclear plants' machine hell is
also connected to Units 1 and 2. An explosion in the machine hall could
have led to the destruction of all four Chernobyl reactors. An explosion
was only averted by spraying nitrogen at the last minute. Four of the eight
people who did this died shortly afterwards.
20.00 hours - A government committee is established, led by
Valery Legasov; at eight o'clock in the evening the committee arrives in
the area. They are surprised by the bits of graphite they see lying around.
None of them suspect a graphite fire.
26 April to 4 May 1986: Most of the radiation is released in the first ten days. At first, southernly and southeasternly winds predominate. The first radioactive cloud went high into the atmosphere and winds blew it northwest away from Ukraine toward Sweden. It was Kiev's good fortune that the wind carried the radioactive cloud away at first rather than directly to the Ukrainian capital and its 3 million population as it did several days later. At the end of April the wind switches to the north and northwest. There are frequent but local showers. This results in a very varied regional and local distribution of the radiation. An estimated 75% of total released radiation contaminates Belarus.[see maps]
27 April (Sunday)
A radius of 10 km around the plant (cities of Pripyat and Yanov) evacuated
(“for three days” they are told) (50.000 people) to the town of Poliske
(50 km west – coincidently -?- wind is blowing in that direction too).
Dosismeters are confiscated.
01.13 hours - The operation of Units 1 and 2 had already been
stopped at 01.13 and 02.13 hours, twenty-four hours after the start of
the accident at Block 4
07.00 hours - General Pikalov sets out in a truck fitted out
with radiation apparatus. He rams through the closed gates and stops at
the plant to measure the radiation. He establishes that the graphite in
the reactor is burning, and that an enormous amount of radiation and heat
is being given off. Shortly afterwards - the government in Moscow is warned.
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28 April (Monday)
Forsmark NPP Sweden (times are Chernobyl-times)
09:00 am An alarm was sent from Reactor 1, where a routine check
revealed that the soles of the shoes worn by a radiological safety engineer
were radioactive.
Lars Wahlström, radiology supervisor at Forsmark, has given this
summary of the events:
"Something indicated that radioactivity had leaked out from one of
the blocks at Forsmark. Rumors about the activity circulated between noon
and 14hours and people said 'Now let's leave here.' At the same time news
arrived that radioactivity had been detected in Finland. I said, I want
evidence. Among other things I called Studsviks Energiteknik AB, where
management was sitting in a crisis meeting and where they said 'We think
it's coming from one of our laboratories.' But that wasn't so. Soon I also
began to have doubts that there was anything wrong in any of the Forsmark
reactors, which I told the National Institute of Radiation Protection.
We had even been inside the chimney and checked. Then the Institute said
the fallout had come from somewhere in the east, and by around 15.30 it
was determined that the fallout definitely did not come from Forsmark."
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20:00 Radio Moscow broadcasts a Tass’ statement that there has
been an accident at the Chernobyl nuclear power station and that there
have been casualties. “Measures are being taken to eliminate consequences
of the accident. Aid is being given to those affected. A government
commission has been set up” according to Tass. From about 30 minutes later
west-european newsagencies are reporting an “incident in a Ukrainian nuclear
reactor”
23:00 A Danish nuclear research laboratory announces that an
MCA (maximum credible accident) has occurred in the Chernobyl nuclear reactor.
They mention a complete meltdown of one of the reactors and that all radioactivity
has been released.
29 April (Tuesday)
- The sixth item on the main television evening news program, Vremya,
says that 2 people died during the accident, a portion of the reactor building
was destroyed, and residents of Pripyat and three nearby towns were evacuated.
- The first real information in the western world came on Tuesday morning,
when a powerful American reconnaissance satellite provided Washington analysts
with photos of Chernobyl. They were shocked to see the roof blown off above
the reactor and the glowing mass still smoking. The first Soviet photos
of the Chernobyl accident were censored by removal of the smoke before
being printed in the newspapers.
- The first official statement by German authorities: Minister of the
Interior Zimmermann states there is no danger for the German public: “danger
only exists in a radius of 30-50 km of the reactor”.
- Polish authorities decide to distribute iodine tablets in the north-east
of the country to infants and children to protect them from thyroid cancer.
30 April (Wednesday)
- Tass carries a government statement denying western reports
on mass casualties. The statement repeats the earlier assertion that only
two people died during the accident and that 197 have been hospitalized
and levels of radiation are decreasing
- Pressreports on fire in second unit: scientist see second fire on
satellite images, claims are later denied
17.00 hours: The reactor fire seems to be extinguished.