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KF5JRV > TODAY 28.03.24 10:01l 57 Lines 4639 Bytes #999 (0) @ WW
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Subj: Today in History - Mar 28
Path: IW8PGT<IZ3LSV<DB0ERF<DK0WUE<DK0WUE<N2NOV<K5DAT<KF5JRV
Sent: 240328/0635Z 19339@KF5JRV.#NWAR.AR.USA.NA BPQ6.0.23
At 4 a.m. on March 28, 1979, one of the worst accidents in the history of the U.S. nuclear power industry begins when a pressur
e valve in the Unit-2 reactor at Three Mile Island fails to close. Cooling water, contaminated with radiation, drained from the
open valve into adjoining buildings, and the core began to dangerously overheat.
The Three Mile Island nuclear power plant was built in 1974 on a sandbar on Pennsylvania’s Susquehanna River, just 10 miles dow
nstream from the state capitol in Harrisburg. In 1978, a second state-of-the-art reactor began operating on Three Mile Island,
which was lauded for generating affordable and reliable energy in a time of energy crises.
After the cooling water began to drain out of the broken pressure valve on the morning of March 28, 1979, emergency cooling pum
ps automatically went into operation. Left alone, these safety devices would have prevented the development of a larger crisis.
However, human operators in the control room misread confusing and contradictory readings and shut off the emergency water sys
tem. The reactor was also shut down, but residual heat from the fission process was still being released. By early morning, the
core had heated to over 4,000 degrees, just 1,000 degrees short of meltdown. In the meltdown scenario, the core melts, and dea
dly radiation drifts across the countryside, fatally sickening a potentially great number of people.
As the plant operators struggled to understand what had happened, the contaminated water was releasing radioactive gases throug
hout the plant. The radiation levels, though not immediately life-threatening, were dangerous, and the core cooked further as t
he contaminated water was contained and precautions were taken to protect the operators. Shortly after 8 a.m., word of the acci
dent leaked to the outside world. The plant’s parent company, Metropolitan Edison, downplayed the crisis and claimed that no ra
diation had been detected off plant grounds, but the same day inspectors detected slightly increased levels of radiation nearby
as a result of the contaminated water leak. Pennsylvania Governor Dick Thornburgh considered calling an evacuation.
Finally, at about 8 p.m., plant operators realized they needed to get water moving through the core again and restarted the pum
ps. The temperature began to drop, and pressure in the reactor was reduced. The reactor had come within less than an hour of a
complete meltdown. More than half the core was destroyed or molten, but it had not broken its protective shell, and no radiatio
n was escaping. The crisis was apparently over.
Two days later, however, on March 30, a bubble of highly flammable hydrogen gas was discovered within the reactor building. The
bubble of gas was created two days before when exposed core materials reacted with super-heated steam. On March 28, some of th
is gas had exploded, releasing a small amount of radiation into the atmosphere. At that time, plant operators had not registere
d the explosion, which sounded like a ventilation door closing. After the radiation leak was discovered on March 30, residents
were advised to stay indoors. Experts were uncertain if the hydrogen bubble would create further meltdown or possibly a giant e
xplosion, and as a precaution Governor Thornburgh advised “pregnant women and pre-school age children to leave the area within
a five-mile radius of the Three Mile Island facility until further notice.ö This led to the panic the governor had hoped to avo
id; within days, more than 100,000 people had fled surrounding towns.
On April 1, President Jimmy Carter arrived at Three Mile Island to inspect the plant. Carter, a trained nuclear engineer, had h
elped dismantle a damaged Canadian nuclear reactor while serving in the U.S. Navy. His visit achieved its aim of calming local
residents and the nation. That afternoon, experts agreed that the hydrogen bubble was not in danger of exploding. Slowly, the h
ydrogen was bled from the system as the reactor cooled.
At the height of the crisis, plant workers were exposed to unhealthy levels of radiation, but no one outside Three Mile Island
had their health adversely affected by the accident and no one died as a result of the accident. Nonetheless, the incident grea
tly eroded the public’s faith in nuclear power. The unharmed Unit-1 reactor at Three Mile Island, which was shut down during th
e crisis, did not resume operation until 1985. Cleanup continued on Unit-2 until 1990, but it was too damaged to be rendered us
able again.
73 de Scott KF5JRV
Pmail: KF5JRV@KF5JRV.#NWAR.AR.USA.NA
Email KF5JRV@gmail.com
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