5 times we almost nuked ourselves by accident

We spent the Cold War in perpetual fear that the U.S. and U.S.S.R.
would start an intentional nuclear conflict. The truth is, we came far closer to
blowing ourselves up with nuclear weapons than we ever came to WWIII.

Nuclear incidents have a bunch of ominous military code names, like Broken
Arrow, Faded Giant or NUCFLASH. There are actually dozens of instances like
these, but here are five major ones that happened in the U.S. If we were to
consider Soviet activity, the list could go on for hours. The Russians either
lost a nuclear sub, lost a sub with nuclear weapons on board, had a nuclear
sub's reactor melt down, or all three roughly every other week. Kompetentnyh?
Nyet.

Travis Air Force Base, 1950 — Broken Arrow

During the Korean War, U.S. military and political officials gave serious
consideration to the use of atomic weapons. In August of 1950, ten B-29
Superfortress bombers took off from what was then called Fairfield-Suisun Air
Force Base in California, headed for Guam. Each was carrying a Mark IV atom
bomb, which was about twice as powerful as the bombs dropped on Japan at the end
of World War II.

Shortly after takeoff, one of the B-29s had engine trouble. On board was
General Robert Travis. He commanded the plane to turn back to the base when the
landing gear refused to retract. Sensing the plane was going down, the pilot
tried to avoid some base housing before crashing at the northwest corner of the
base. The initial impact killed 12 of the 20 people aboard, including General
Travis. The resulting fire eventually detonated the 5,000 pounds of conventional
explosives that were part of the Mark IV. That massive explosion killed seven
people on the ground. Had the bomb been armed with its fissile capsule, the
immediate death toll may have reached six figures.

The Air Force covered up the incident, blaming it on conventional bombs
loaded for a training flight. The base was renamed for General Travis just a few
months later. The term Broken Arrow refers to nuclear incidents which are not
likely to start a nuclear war.

Fermi 1 breeder reactor, 1966 —
Faded Giant

This incident was immortalized as the night "We Almost Lost Detroit" by both
John Fuller's book of the same name (with the terrifying cover), and Gil
Scott-Heron's groovy slow jam about nuclear nightmares.

What happened at Fermi 1 was the result of engineering mistakes, lax safety
standards and simple inexperience at building nuclear reactors. The designers
made changes to the cooling system without documenting them, so the engineers
working on the reactor didn't know that there were extra dispersion plates in
the liquid sodium containment tank. When one of the tanks blocked the coolant
pipes, the reactor core overheated to 700 degrees F and partially melted
down.

In a meltdown, the reactor fuel overheats beyond the point that the cooling
system can handle. It eventually begins to melt the infrastructure surrounding
it, such as containment casings, cooling systems and, in extreme cases, the
floor of the installation. In a full meltdown, the fuel catches fire and
sustains itself at about 2,000 degrees F. Although the term wasn't in use in
1966, the hypothetical (and technically impossible) chance of a burning reactor
melting its way through the Earth all the way to China gives us the term "China
Syndrome."

Fermi 1 actually sits in between Detroit and Toledo, but I guess "We Almost
Lost Toledo" doesn't have quite the same ring to it. Faded Giant, by the way, is
the codeword for a non-weapon nuclear incident like this (who actually goes
around using these code words, I have no idea).

Tybee Island,
1958 — Broken Arrow

In the waters off Tybee Island, Georgia, right at the Georgia/South Carolina
border and not far from Savannah, buried in about 10 feet of silt is a hydrogen
bomb. It's been there for more than 50 years.

In 1958, a B-47 Stratojet bomber suffered a mid-air collision during training
exercises. It was carrying a Mark 15 hydrogen bomb at the time – a lightweight
bomb 12 feet long and carrying 400 pounds of explosives and highly enriched
uranium. The damaged bomber's crew decided that this wasn't the sort of thing
they wanted to be carrying when they attempted a crash landing, so they asked
for and received permission to dump the bomb in the ocean. It did not explode
when it hit the water, and was never seen again.

There is some discrepancy as to whether the bomb was fully armed. Some
reports suggest it was, but the Air Force officially lists it as containing a
dummy capsule. Several attempts have been made to locate it, but the natural
radiation of the surrounding geology has made this difficult. If it had been
armed, and had detonated, the city of Savannah would have pretty much
disappeared.

Idaho Falls, 1961 — Faded Giant

You're probably expecting to find Three-Mile Island on this list. That was
potentially a serious disaster, and it did release radioactive gas into a
populated area. But the Idaho Falls incident stands out as the most gruesome
U.S. nuclear disaster, and it's relatively little known.

The SL-1 reactor was an experimental reactor run by the U.S. Army near Idaho
Falls, Idaho. On the night of January 3, 1961, heat alarms went off. Nearby
emergency personnel made their way to the scene. They could not reach the
control room for more than an hour and a half because of high radiation levels.
When they did, they found two victims, one clinging to life (he died not long
after). Even after being removed from the reactor building, the corpses
themselves were so radioactive they had to be buried in lead and concrete
tombs.

The worst was still to come. Several days later, rescue crews found the third
operator. He had been standing atop the reactor when the incident occurred, and
the force of the explosion had blasted a control rod up and through his chest,
pinning him to the ceiling.

The key to the incident was the crew's ability to control the rate of the
reaction. A sustainable reaction requires each fission event to generate enough
neutrons to strike an additional atom, generating one more fission event.
Control is maintained by manipulating the probability of a neutron causing
fission, mainly through control rods of a material that harmlessly absorbs the
neutrons. Putting more controls rods into the reactor slows the reaction. SL-1
was undergoing maintenance that required a few inches of the main control rod to
be removed. Since this reactor design used one big control rod, a single mistake
(withdrawing almost the entire control rod) caused the reaction to instantly go
supercritical – fission events occurring and exponentially multiplying.

The massive jump in energy output vaporized the water coolant and parts of
the reactor itself, resulting in a powerful explosion. The explosion itself
caused the reaction to halt. I'm still waiting for Gil Scott-Heron to write "We
Almost Lost Idaho Falls."

NORAD, 1979 — NUCFLASH (almost)

This is how NORAD learned not to run computer simulations of Soviet nuclear
attacks on the systems used to respond to actual Soviet nuclear attacks. The
missile defense agency received alarming indications that a full scale battery
of Russian nukes were heading toward the U.S. Planes were scrambled with fully
armed nuclear weapons. The president's shielded emergency plane was put into the
air too (although they couldn't get the president on it in time).

Fingers hovered over buttons. Commanders of flight crews waited for word to
strike. For six tense minutes, no one was sure if World War III was
happening…and oddly, no one used the "red phone" hotline to ask the Soviets.
Finally, word came from Advanced Early Warning radar and satellites that no
missiles were detected. The culprit? A training tape had accidentally been run
and generated the false positive signals. In military parlance, a NUCFLASH is an
actual nuclear detonation that might lead to an outbreak of nuclear war.

An honorable mention goes to the Duluth bear, in which a guard saw a bear
climbing a fence at an Air Force base and rang an alarm. The alarm connected to
other nearby bases, but one of them was wired wrong, so instead of "intruder
alert!" they got the "Nuke Russia Now!" alarm. Nuclear armed jets were on the
runways ready to take off before the mistake was rectified.

If that doesn't seem scary enough, there are dozens more incidents like these
on the U.S. side alone. We haven't even touched on the Cuban Missile Crisis. The
sad lesson is that we have less to fear from naked aggression than we do from
incompetence and bad engineering.

Sources:

Farmer, James H. "Korea and the A-Bomb." Flight Journal, Dec. 2010.

"The SL-1 Reactor Accident." Radiationworks.

"Nuclear Accidents." Georgia
State University.

"Criticality Accidents." Trinity Atomic
Website.