Chernobyl Nuclear Power Plant CIA Files - Paperless Archives

Chernobyl Nuclear Power Plant Accident CIA, Department
of Defense, Department of Energy, Congressional, GAO,
and Foreign Press Monitoring Files
4,010 pages of CIA, Department of Defense, Department of Energy,
Congressional, GAO, and foreign press monitoring files related to the
Chernobyl Nuclear Accident.
On Sunday April 26, 1986, at the Chernobyl Nuclear Power Plant near
Pripyat, Ukraine, reactor #4 exploded. For the 25 years from 1986 to
2011, this incident has been referred to as the world's worst nuclear
power plant accident.
THE ACCIDENT
According to reports filed with International Atomic Energy Agency (IAEA)
on April 25, 1986, technicians at the Chernobyl plant launched a poorly
executed experiment to test the emergency electricity supply to one of
its Soviet RBMK type design reactors. The test was meant to measure a
turbogenerator's ability to provide in-house emergency power after
shutting off its steam supply. During the experiment the technicians
violated several rules in place for operating the reactor.
During the experiment, the emergency shutdown system was turned off. The
reactor was being operated with too many control rods withdrawn. These
human errors, coupled with a design flaw that allowed reactor power to
surge when uncontrolled steam generation began in the core, set up the
conditions for the accident.
A chain of events lasting 40 seconds occurred at 1:23 AM on April 26.
The technicians operating the reactor put the reactor in an unstable
condition, so reactor power increased rapidly when the experiment began.
Subsequent analysis of the Soviet data by U.S. experts at the Department
of Energy, suggests the power surge may have accelerated when the
operators tried an emergency shutdown of the reactor. According to Soviet
data, the energy released was, for a fraction of a second, 350 times the
rated capacity of the reactor. This burst of energy resulted in an
instantaneous and violent surge of heat and pressure, rupturing fuel
channels and releasing steam that disrupted large portions of the core.
The surge destroyed the core of reactor unit four, containing
approximately 200 tons of nuclear fuel. Some of the shattered core
material was propelled through the roof of the reactor building. The hot
core material of reactor 4 started about 30 separate fires in the unit 4
reactor hall and turbine building, as well as on the roof of the
adjoining unit 3. All but the main fire in the graphite moderator
material still inside unit 4 were extinguished in a few hours.
It was a day and a half before the people living in Pripyat were ordered
to evacuate. The residents were told they would only be gone for several