North Korea claims it has detonated a hydrogen bomb.

[davidm]

http://news.yahoo.com/n-korea-says-conducted-successful-hydrogen-bomb-test-033750240.html

The announcement by North Korean state media came two days before Kim’s birthday and just over four years after he succeeded his father as leader of the Stalinist state.

Suspicions over a possible nuclear test – Pyongyang’s fourth – were first raised by seismologists who said they had detected a 5.1 magnitude tremor next to its main atomic test site in the northeast of the country.

The website of the China Earthquake Network Centre described the seismic activity as a “suspected explosion”, while the Japanese government said there was a strong possibility that “this might be a nuclear test”.

[Ike_Witt]

Can they actually build a fusion device? They haven’t had the best luck with fission devices in the past.

[coremelt]

Looks legit, or at least it hasn’t been denied by any US officials or South Korea as yet.

North Korea hydrogen bomb test: 'successful' nuclear bomb a strategic move

The question now is do they have any delivery vehicle that could get it to Seoul? ( Or Japan?) Eg is it small enough to fit on a missile? On a related note maybe this will now push the US to sell a THAAD anti missile system to South Korea.

Washington Waffles on Korean Missile Defense, Delighting China and Russia

[AK84]

@Ike_Witt

Can they actually build a fusion device? They haven’t had the best luck with fission devices in the past.

They have been working on it for 10 years. Does not mean that they are forever stuck at the same level.

Plus it might not be a true multi stage weaopon rather a type of boosted fission device.

1.5.1 Boosted Fission Weapons

The earliest application of fusion to useful weapons was the development of boosted fission weapons. In these weapons a few grams of a deuterium/tritium gas mixture are included in the center of the fissile core. When the bomb core undergoes enough fission, it becomes hot enough to ignite the D-T fusion reaction which proceeds swiftly. This reaction produces an intense burst of high-energy neutrons that causes a correspondingly intense burst of fissions in the core. This greatly accelerates the fission rate in the core, thus allowing a much higher percentage of the material in the core to fission before it blows apart. Typically no more than about 20% of the material in an average size pure fission bomb will split before the reaction ends (it can be much lower, the Hiroshima bomb was 1.4% efficient). By accelerating the fission process a boosted fission bomb increase the yield 100% (an unboosted 20 kt bomb can thus become a 40 kt bomb). The actual amount of energy released by the fusion reaction is negligible, about 1% of the bomb’s yield, making boosted bomb tests difficult to distinguish from pure fission tests (detecting traces of tritium is about the only way).

Or maybe the hybrid “Layer Cake”

This idea predates the invention of staged radiation implosion designs, and was apparently invented independently at least three times. It was first devised by Edward Teller in the United States, who named the design “Alarm Clock”. Later Andrei Sakharov and Vitalii Ginzburg in the Soviet Union hit upon it and dubbed it the “sloika” design. A sloika is a layered Russian pastry, rather like a napoleon, and has thus been translated as “Layer Cake”. Finally it was developed by the British (inventor unknown). Each of these weapons research programs hit upon this idea before ultimately arriving at the more difficult, but more powerful and efficient, staged thermonuclear approach.

This system was dubbed “Layer Cake” by the Soviets because it uses a spherical assembly of concentric shells. In the center is a fission primary made of U-235/Pu-239, surrounding it is an (optional) layer of U-238 for the fission tamper, then a layer of lithium-6 deuteride/tritide, a U-238 fusion tamper, and finally the high explosive implosion system. The process begins like an ordinary implosion bomb. After the primary in the center completes its reaction, the energy it releases compresses and heats the fusion layer to thermonuclear temperatures. The burst of fission neutrons then initiates a coupled fission-fusion-fission chain reaction. Slower fission neutrons generate tritium from the lithium, which then fuses with deuterium to produce very fast neutrons, that in turn cause fast fission in the fusion tamper, which breed more tritium. In effect the fusion fuel acted as a neutron accelerator allowing a fission chain reaction to occur with a large normally non-fissionable U-238 mass. While spiking the fusion layer with an initial dose of tritium is not strictly necessary for this approach, it helps boost the yield.

The achievable fusion fraction is fairly small, 15-20%, and cannot be increased beyond this point. Its use of fusion fuel is also quite inefficient. This design is also limited to the same yield and yield-to-weight range as high yield pure fission and boosted fission weapons. This was developed into a deliverable weapon by the Soviet Union and the British prior to their development of the staged designs described above. The U.S. did not bother to pursue it, partly because Teller did not feel it was sufficiently destructive to be worthwhile.

[coremelt]

Yep, this article quotes an Analyst saying its a boosted weapon not a true fusion bomb. Which means its theoretical yield is “only” around 50 kilotons.

http://www.wmur.com/national/north-korea-hbomb-test-key-questions/37286628

[coremelt]

Tweet from a Journalist claims the US will send sniffer plans to the area to detect traces of isotopes and analyse the blast in detail.

Molly Hunter

[Diceman]

@coremelt

The question now is do they have any delivery vehicle that could get it to Seoul? ( Or Japan?) Eg is it small enough to fit on a missile? On a related note maybe this will now push the US to sell a THAAD anti missile system to South Korea.
Washington Waffles on Korean Missile Defense | Observer

Seoul? Absolutely. They could damn-near use a catapult to get it there.

Japan? Probably in a year or two. They say they’re close to miniaturizing the weapon. “Miniaturized” in this case meaning put on a warhead. They already have missles that can reach Japan. I remember a number of years ago they fired a missle that flew over Japan and landed in the Pacific Ocean on the far side. As you might imagine, the Japanese were less than happy.

[Siam_Sam]

The graphic in this report shows a range of 5600 miles or 9000 kilometers. But this is hard to believe. Surely that can’t be right.

[Machine_Elf]

@coremelt

The question now is do they have any delivery vehicle that could get it to Seoul?

They could put it on some kind of dick.

Wait, I mean a Taepodong.

[davidm]

If this chart, from CNN, is correct then the magnitude is no greater than their 2013 test.

[bump]

@coremelt

Yep, this article quotes an Analyst saying its a boosted weapon not a true fusion bomb. Which means its theoretical yield is “only” around 50 kilotons.

You’re WAY off… considering that you can get about 500 kilotons out of pure fission weapons, you can probably get close to twice that with boosted fission weapons. Boosted fission weapons weren’t ever a major strategic direction for the US in their own right, as fusion weapons came along very quickly. But they’re commonly used in fusion primaries to reduce the size(or in dial-a-yield weapons, you can choose to boost or not as one of the yields), so maybe that’s why you’re thinking they can only be 50 kt or so.

And if the magnitude of the tremors is no larger than their last test, it wasn’t any larger than about 15 kilotons at most, which either points toward a very sophisticated boosted fission weapon, or some kind of fizzle or failed test.

[Diceman]

@Siam_Sam

The graphic in this report shows a range of 5600 miles or 9000 kilometers. But this is hard to believe. Surely that can’t be right.

What’s hard to believe about it? We were making rockets that could reach the Moon in the 1960’s. Plus, North Korea has gotten plenty of off-the-books help from China (and maybe Russia) over the years.

[Chefguy]

@Diceman

What’s hard to believe about it? We were making rockets that could reach the Moon in the 1960’s. Plus, North Korea has gotten plenty of off-the-books help from China (and maybe Russia) over the years.

Apparently China is furious over this test so close to their border, so future help may be tough to get.

[Diceman]

@Chefguy

Apparently China is furious over this test so close to their border, so future help may be tough to get.

Well, they say they’re furious about it. It may be true, or it may just be window dressing. You never can be sure with those sorts of official statements.

Altho, North Korea has been doing nuclear testing in that same area for years now, so I rather doubt the location was a surprise to Beijing.

[davidm]

I’m skeptical that China didn’t know about this test and doesn’t know how the program is going in general.

[billfish678]

I’m kinda looking forward to the day China has to deal with 20 million malnourished, physically and mentally stunted refugees.

The have had a good part in making this mess.

[Velocity]

Is it possible for a thermonuclear weapon to be *weaker *than 7 kilotons?

[si_blakely]

Let’s look at the evidence - the seismic data indicates something similar in yield to the 2013 test. That device wasn’t a fusion device, so this one is unlikely to be either. Even the fission yield is on the low side, so they do not have anything to boast about - poorly implemented fission weapons that might be just approaching deliverable devices. The likely yield does not even indicate a boosted device, let alone a hydrogen (fusion) bomb.
NK news claimed to show video of a typical “mushroom” cloud from the test. That would suggest an above-ground test - the fallout from such a test would be all over the region, and particulate evidence would be easy to collect. But I doubt it was actually an above-ground test, no one does that any more. The footage was probably stock video for propaganda purposes.

So a barely working fission device with inflated claims, in my opinion.

[AK84]

A “barely working fission device” is enough to fuck up any city on earth and cause millions to have a lousy morning.

[si_blakely]

@AK84

A “barely working fission device” is enough to fuck up any city on earth and cause millions to have a lousy morning.

One city, if they were really lucky. There are other regimes with actually working weapons that could pose a significantly higher threat to international safety and security.

North Korea has had four attempts, none of which have approached the yield of a typical “first device”. They do not seem to be improving, so their technical capabilities appear to be weak. Are they a risk - yes. Their leader is probably certifiable. But the actual device is still probably not deliverable except in a 20’ container, and and provides no deterrence capability at this stage.

I’d rather worry about real threats.