Power Plant Engineering

T.M.I. Aaccount Chronology in Brief
1970’s AEC LOFT (Loss of Fluid Test) research canceled as economy measure.
September 12, 1978 T.M.I. Unit #2 dedicated.
January 1979 TMI #2 began commercial operation.
March 26, 1979 Emergency core cooling pumps tested, with diverter valves switched to discon-
nect ECCS from reactor. Valves not switched back.
March 28, 1979, 4 a.m. Three Mile Island Incident began.
—Filter in inner loop switched offline to clean
—Pressure transient triggers shutdown sequence.
—Core overheats, pressure relief valve sticks open, in manual override
—Water in core begins leaking out open relief valve
—Emergency cooling pumps don’t work !
—After more errors, 1/3 of core exposed, partial meltdown of fuel rods results.
—2nd day someone closes relief valve (unrecorded).. situation stabilizes
—hydrogen gas bubble forms.
—Governor/NRC, order partial evacuation
Cleanup/termination cost $1.5+ BILLION.
Cleanup after the Three Mile Island Accident. After the Accident it was necessary to dispose
of the radioactive gases, water, and contaminated debris from radioactive plumbing etc. The water had
to be filtered to separate and concentrate radioactive contaminants for disposal. After these were re-
moved it was possible to begin dismantling the pressure vessel and extract the fuel rods. It was not until
then that the inside of the core could be inspected. As the damaged reactor was brought under control, it
was known from radiation monitoring that there was a significant amount of radioactive material in the
bottom of the pressure vessel. In spite of this, the power company still maintained that the damage to the
core had been minimal. When a robot with a video camera was lowered into the pressure vessel, four
years after the accident, this is what it saw:
10.26 CHERNOBYL NUCLEAR POWER PLANT
Chernobyl is a town of 30,000 people, 70 miles north of Kiev, in the Ukraine. The V. I. Lenin
nuclear power plant is located 10 miles from the town of Chernobyl. Adjacent to the plant is the town of
Pripyat, which houses and services plant workers. The plant is on the Pripyat River, near its mouth into
the Kiev reservoir.
The plant had 4 nuclear reactors, each with associated steam turbines and electric generators.
Two additional units were under construction at the time of the accident, April 26, 1986. Each of these
units was of the same Soviet design, designated RBMK-1000.
Chernobyl was the location of the world's worst nuclear power plant disaster. Massive amounts
of radioactivity were released, a thousand square mile area will be uninhabitable for many decades.

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POWER PLANT ENGINEERING