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KF5JRV > TODAY 28.03.19 12:42l 77 Lines 4082 Bytes #999 (0) @ WW
BID : 33523_KF5JRV
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Subj: Today in History - Mar 28
Path: IZ3LSV<IW8PGT<CX2SA<N9PMO<KM8V<KE0GB<KF5JRV
Sent: 190328/1138Z 33523@KF5JRV.#NWAR.AR.USA.NA BPQ6.0.18
At 4 a.m. on March 28, 1979, the worst accident in the history of the
U.S. nuclear power industry begins when a pressure 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 downstream 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 pumps 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 system. 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
deadly 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 throughout the plant.
The radiation levels, though not immediately life-threatening, were
dangerous, and the core cooked further as the contaminated water was
contained and precautions were taken to protect the operators. Shortly
after 8 a.m., word of the accident leaked to the outside world. The
plant’s parent company, Metropolitan Edison, downplayed the crisis and
claimed that no radiation 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 pumps. 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 radiation 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 this gas had exploded,
releasing a small amount of radiation into the atmosphere. At that time,
plant operators had not registered 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
explosion, 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 avoid; 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 helped
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 hydrogen was bled from the system as
the reactor cooled.
73 de Scott KF5JRV
Pmail: KF5JRV@KF5JRV.#NWAR.AR.USA.NA
email: KF5JRV@ICLOUD.COM
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