How is the yield from a nuclear bomb measured?

Divine Angel said:

How is the yield from a nuclear bomb measured?

Tons equivalent TNT last I saw

“WIKII Yield”:ttps://en.wikipedia.org/wiki/Nuclear_weapon_yield#Calculating_yields_and_controversy

WIKI Yield

Could you not calculate the yield from the amount of fissionable material in the bomb and its likely conversion rate before that material gets vapourised

Divine Angel said:

How is the yield from a nuclear bomb measured?

Very carefully.

• How is the yield from a nuclear bomb measured?

It taps the mat…

Divine Angel said:

How is the yield from a nuclear bomb measured?

With a very long tape measure

CrazyNeutrino said:

Divine Angel said:

How is the yield from a nuclear bomb measured?

With a very long tape measure

Nagasakians / m>2

If it is being assessed on the basis of surface tests, they measure the wind velocities at various locations and work it out from there.

dv said:

If it is being assessed on the basis of surface tests, they measure the wind velocities at various locations and work it out from there.

Are we still talking about bubblecar’s pea and ham soup?

Divine Angel said:

How is the yield from a nuclear bomb measured?

The “yield” is an energy (not a power). The metric equivalent would be in Joules.
1 ton of TNT is 4.183*10^9 Joules, which is 4.183 Gigajoules
A typical atomic (eg. U or Pu) bomb might be 10 kilotons, or 41.83 Terajoules
A typical hydrogen (eg. tritium or lithium deuteride) bomb might be 10 megatons, or 41.83 Petajoules.

Divine Angel said:

How is the yield from a nuclear bomb measured?

Oh wait, are you asking about how the observed damage is used to generate an estimate of the yield? I can think of three ways that have been used.

The first way, used for the first above-ground “Trinity” test, was for first set off an explosion made from 100 tons of TNT next to the test site. Then use computer models (perhaps of crater diameter) to extrapolate from that to the yield of the actual test.

For underground testing, the yield is estimated from the strength of the seismograph signals. Even today, the energy released in an earthquake is estimated using this information, and given in the “moment magnitude” scale. Magnitude 2 is 56 kg of TNT, magnitude 3 is 1.8 tons of TNT, magnitude 4 is 56 tons of TNT, magnitude 5 is 1.8 kilotons, magnitude 6 is 56 kilotons, etc. There was a rather dangerous time in the late cold war where the USA’s calculation of the energy contained in nuclear tests by the USSR using this method was overestimating the yield by about a factor of two.

More recently than that, the yield of a nuclear explosion as measured by a satellite is estimated from the intensity of gamma rays emitted at the underground testing site.

Cymek said:

Could you not calculate the yield from the amount of fissionable material in the bomb and its likely conversion rate before that material gets vapourised

Apparently not. I was watching a doco called The World’s Biggest Bomb. The Americans developed Bravo Charlie and the yield was bigger than expected because they didn’t know Lithium 7 wasn’t inert (they had counted on Lithium 6 being the factor in detonation, but not Li 7). So instead of being 5 million tonnes, it turned out to be 15 million.

mollwollfumble said:

Divine Angel said:

How is the yield from a nuclear bomb measured?

Oh wait, are you asking about how the observed damage is used to generate an estimate of the yield? I can think of three ways that have been used.

The first way, used for the first above-ground “Trinity” test, was for first set off an explosion made from 100 tons of TNT next to the test site. Then use computer models (perhaps of crater diameter) to extrapolate from that to the yield of the actual test.

For underground testing, the yield is estimated from the strength of the seismograph signals. Even today, the energy released in an earthquake is estimated using this information, and given in the “moment magnitude” scale. Magnitude 2 is 56 kg of TNT, magnitude 3 is 1.8 tons of TNT, magnitude 4 is 56 tons of TNT, magnitude 5 is 1.8 kilotons, magnitude 6 is 56 kilotons, etc. There was a rather dangerous time in the late cold war where the USA’s calculation of the energy contained in nuclear tests by the USSR using this method was overestimating the yield by about a factor of two.

More recently than that, the yield of a nuclear explosion as measured by a satellite is estimated from the intensity of gamma rays emitted at the underground testing site.

Thanks moll, that’s what I was looking for.

Is measuring nuke yields in kgs of TNT the same as measuring water in the number of Sydney Harbours? ;)

Morning punters and correctors, cold in the Pearl, should warm up to a nice winters day later, although the dart throwers were mentioning a bit of rain, but I was harf (I decided not to use the l to save on my data allowance, it sounds the same without the l anyway) asleep so it might be tomorrow for the rain.

Divine Angel said:

mollwollfumble said:

Divine Angel said:

How is the yield from a nuclear bomb measured?

Oh wait, are you asking about how the observed damage is used to generate an estimate of the yield? I can think of three ways that have been used.

The first way, used for the first above-ground “Trinity” test, was for first set off an explosion made from 100 tons of TNT next to the test site. Then use computer models (perhaps of crater diameter) to extrapolate from that to the yield of the actual test.

For underground testing, the yield is estimated from the strength of the seismograph signals. Even today, the energy released in an earthquake is estimated using this information, and given in the “moment magnitude” scale. Magnitude 2 is 56 kg of TNT, magnitude 3 is 1.8 tons of TNT, magnitude 4 is 56 tons of TNT, magnitude 5 is 1.8 kilotons, magnitude 6 is 56 kilotons, etc. There was a rather dangerous time in the late cold war where the USA’s calculation of the energy contained in nuclear tests by the USSR using this method was overestimating the yield by about a factor of two.

More recently than that, the yield of a nuclear explosion as measured by a satellite is estimated from the intensity of gamma rays emitted at the underground testing site.

Thanks moll, that’s what I was looking for.

Is measuring nuke yields in kgs of TNT the same as measuring water in the number of Sydney Harbours? ;)

Yes.