H-Bomb Dropped on U.S.

This is the 57th anniversary of the date that a thermonuclear bomb “device” was dropped on the U.S.  Surprisingly, some people are unaware that it ever happened, just as some don’t know that one of our H-bombs has killed a Japanese citizen.

The wayward bomb was an Mk-15, one of the proud products of my hometown, dropped just off Tybee Island, GA by a USAF B-47 Stratojet bomber on Feb. 5, 1958.  It was one of those incidents that happens during war games (the kind in which participants play for keeps) where the bomber collided with a fighter jet and jettisoned its live H-bomb a little over a mile off Tybee before attempting to land.  (I’m slightly exaggerating about the “games”; it was really a “training mission”.)  The B-47 was from Hunter Army Airfield (HAAF), where my son was stationed.  The bomb was not yet armed, so it didn’t detonate, and it’s never been recovered.  It’s in about 12 feet of water, so it should be easy to get to, and it only weighs about 2 tons (which was considered light-weight).


The Mk-15 comes is three models.  The mod 1 is identical to the Zombie prototype bomb (don’t you love the names?), while the mod 2 & 3 both have a 3.8 megaton blast.  That’s enough that you wouldn’t want to be anywhere near Tybee or Savanna if it should go off – maybe a hundred miles will give you sufficient time to get out of the way of the fallout.

In 1998, Air Force lieutenant colonel, Derek Duke thought he would look for the lost bomb, and in July 2004 claimed to have found its location around Wassaw Sound, which connects to the Wilmington River.  If you care to read the official Air Force report, that’s right where the pilot said he dropped it.  It’s still there for the taking, but there must be a mummy’s curse or something, because not even the Air Force seems interested in recovering it.

By the way, if you go looking for information on H-bombs, disregard anything you see in Yahoo.  They think we dropped H-bombs on Hiroshima and Nagasaki.

There’s something even more frightening.  Canadian Broadcasting says that it has been declassified.  Leave it to the Canadians – we wouldn’t want to upset the Americans.  They’d better be right or I’m in deep doo-doo.  Since they have all the details, I think I’m safe.  On Jan. 24, 1961 – 3 years after Tybee Island – a B-52 Stratofortress carrying two live Mk-39 thermonuclear devices, broke up in mid-air during a tail-spin, releasing both bombs near Faro, NC.  (They are sometimes called “the Goldsboro bombs” because that is where the Seymour Johnson Air Force base is located.)


Like its predecessor, the Mk-15, the Mk-39 mod 2 was a bomb with a 3.8 megaton blast.  It was a “cleaner” bomb that weighed a little over 3 tons.

On one of the bombs, the parachute deployed and all “fail-safe” switches but one were activated.  The one switch was a simple on-off type which could have easily short-circuited with the jolt when the bomb landed, causing detonation.  Pleasant dreams.

Probably our best-known and loved bomb, Castle Bravo, is the our only H-bomb to have actually killed someone.  It was our first attempt at detonating a “dry” H-bomb.  It’s predecessor (Ivy Mike) used liquid hydrogen (deuterium and tritium) to fuel the blast.  One of my articles from at least a couple years ago had a photo of this bomb.

The Castle Bravo bomb was a simple cylinder about 15 feet long and 4.5 feet in diameter, weighing just short of 12 tons.  The bomb was lovingly named “Shrimp”, probably because it was so much smaller than the cryogenic coolers that were part of Ivy Mike.  Although they wanted to used lithium-6 deuteride as the fuel, they had to settle for lithium-6 contaminated with a heavy dose (60%) of lithium-7.  There was one other modification.  It had a massive depleted uranium (U-238) casing to delay the expansion and intensify the explosion.

Shrimp blew up Namu Island and Bikini Atoll, but in spite of all our efforts, it didn’t stop the namesake swimwear craze.  It was designed to have a 5 megaton blast, but it turned out to have slightly more power than that – estimates have the blast somewhere between 15 and 20 megatons.  Both the lithium-7 with its over-abundant release of neutrons and the fissioning of the supposedly unfissionable U-238 added tremendously to the power of Shrimp and increased its radioactivity over a thousand-fold.  Within a second, the fireball was already 4.5 miles across and could be seen 250 miles away.  It was the most powerful bomb the U.S. has ever detonated.

The fallout was horrendous and contaminated two nearby atolls for 2 days before the U.S. evacuated the residents.  The contamination was responsible for a drastic increase in birth defects in the Marshall Islands.  The Japanese fishing boat, the not-so-Lucky Dragon (Daigo Fukuryū Maru), was so heavily contaminated from the fallout that the entire crew suffered from radiation sickness, with one of the crew dying.  Japanese scientists collecting material from the Lucky Dragon No.5 proved the fallout contamination was far greater than officially admitted.

Yes, today is a day to celebrate all of America’s great accomplishments in keeping the world safe.


2 responses to “H-Bomb Dropped on U.S.

  1. Very clever..lol..device. 😀 So I have your hometown to thank for that monstrosity that sits in Wassaw Sound 😉 ? Yes.. The good ole bomb that created such a stir some years ago before it was (semi) located. Some say it is leaking while others say it isn’t. Well, it’s not ticking (joking) but it’s definitely an issue that gets swept under the rug. I’m not sure if anyone will come clean about how dangerous it really is–no one is interested in doing anything about it. I think the ones who know the truth are going to be dead before the truth is discovered or at least that was their plan. Given that I live just outside the 100 mile fallout ring, I think I would rather live on Wilmington Island if it should blow and be the worst case scenario.

    My dad could never talk about what he did at SRS and it was never declassified while he was alive. I’m sure he had stories to tell about all of these events but I never heard them. I would love to know what he knew. Great post.

    Weapons of mass destruction… and memories of the “cold war.” Just think if the Wassaw Sound bomb had gone off in 1958…I wonder what the history books would say. Ah..the secrets.. And the million dollar question for me is, “Am I a product of some of the secrets and classified information that has been redacted?” I’ll never know. Take care!

  2. Sorry; I was out of town when you sent this. What I’m worried about is that the bomb in Wassaw Sound shouldn’t be hard to retrieve, and there may be people motivated enough to do it. The seals on the Mk-15 were pretty good, but any leakage would destroy the ability to detonate the bomb.

    One of the major products coming out of SRS was tritium, originally intended for the deuterium-tritium cryogenic H-bomb in the Ivy Mike test in late 1952. After that, we went to the Ulam-Teller design in 1954. Since tritium has so many other uses like testing for water leaks and night sights for firearms, it continues to be manufactured.

    You may not be old enough to remember the AEC cars preceding and following shipments coming out of the plant, but for Oak Ridge, the shipments were unmistakable, the AEC agents all carried machine guns.

    Ah, yes. The good old days. Those were simpler times when black was black and white was white and there was nothing in between. I’m glad they’re over.

    I had no idea your dad was at Savanna River. I guess you know what it is like growing up in secrecy. It’s such an other-worldly experience.

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