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N0KFQ > TODAY 26.04.12 23:36l 78 Lines 3718 Bytes #999 (0) @ WW
BID : 21589_KB0WSA
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Subj: Today in History - Apr 26
Path: IZ3LSV<IW0QNL<IK6ZDE<F1OYP<VE2PKT<ZL2BAU<N0KFQ<KB0WSA
Sent: 120426/2114Z 21589@KB0WSA.MO.USA.NA BPQ1.4.49
Apr 26, 1986:
Nuclear disaster at Chernobyl
On April 26, 1986, the world's worst nuclear power plant accident
occurs at the Chernobyl nuclear power station in the Soviet
Union. Thirty-two people died and dozens more suffered radiation
burns in the opening days of the crisis, but only after Swedish
authorities reported the fallout did Soviet authorities
reluctantly admit that an accident had occurred.
The Chernobyl station was situated at the settlement of Pripyat,
about 65 miles north of Kiev in the Ukraine. Built in the late
1970s on the banks of the Pripyat River, Chernobyl had four
reactors, each capable of producing 1,000 megawatts of electric
power. On the evening of April 25, 1986, a group of engineers
began an electrical-engineering experiment on the Number 4
reactor. The engineers, who had little knowledge of reactor
physics, wanted to see if the reactor's turbine could run
emergency water pumps on inertial power.
As part of their poorly designed experiment, the engineers
disconnected the reactor's emergency safety systems and its
power-regulating system. Next, they compounded this recklessness
with a series of mistakes: They ran the reactor at a power level
so low that the reaction became unstable, and then removed too
many of the reactor's control rods in an attempt to power it up
again. The reactor's output rose to more than 200 megawatts but
was proving increasingly difficult to control. Nevertheless, at
1:23 a.m. on April 26, the engineers continued with their
experiment and shut down the turbine engine to see if its
inertial spinning would power the reactor's water pumps. In fact,
it did not adequately power the water pumps, and without cooling
water the power level in the reactor surged.
To prevent meltdown, the operators reinserted all the 200-some
control rods into the reactor at once. The control rods were
meant to reduce the reaction but had a design flaw: graphite
tips. So, before the control rod's five meters of absorbent
material could penetrate the core, 200 graphite tips
simultaneously entered, thus facilitating the reaction and
causing an explosion that blew off the heavy steel and concrete
lid of the reactor. It was not a nuclear explosion, as nuclear
power plants are incapable of producing such a reaction, but was
chemical, driven by the ignition of gases and steam that were
generated by the runaway reaction. In the explosion and ensuing
fire, more than 50 tons of radioactive material were released
into the atmosphere, where it was carried by air currents.
On April 27, Soviet authorities began an evacuation of the 30,000
inhabitants of Pripyat. A cover-up was attempted, but on April 28
Swedish radiation monitoring stations, more than 800 miles to the
northwest of Chernobyl, reported radiation levels 40 percent
higher than normal. Later that day, the Soviet news agency
acknowledged that a major nuclear accident had occurred at
Chernobyl.
In the opening days of the crisis, 32 people died at Chernobyl
and dozens more suffered radiation burns. The radiation that
escaped into the atmosphere, which was several times that
produced by the atomic bombs dropped on Hiroshima and Nagasaki,
was spread by the wind over Northern and Eastern Europe,
contaminating millions of acres of forest and farmland. An
estimated 5,000 Soviet citizens eventually died from cancer and
other radiation-induced illnesses caused by their exposure to the
Chernobyl radiation, and millions more had their health adversely
affected. In 2000, the last working reactors at Chernobyl were
shut down and the plant was officially closed.
73, K.O. and Billie
"On the Road Again... "
E-Mail: n0kfq@winlink.org
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