Weaponising the Grapple tests.

Riain · Aug 28, 2015

Britain only bought into service 3 nuclear weapons of its own design; the Blue Danube, Green Grass and Red Beard. These were all basic fission weapons, in the case of Green Grass a real whopper and very unsafe and difficult to handle in service conditions.

in 1957-8 Britain undertook operation Grapple, a series of nuclear tests culminating in efficient thermonuclear devices. These results were the main reason the US extended nuclear cooperation again in 1958. All British nuclear warheads after 1958 are Anglicised versions of US designs and often use US nuclear materials such as tritium and the like.

WI this nuclear cooperation didn't occur, or was perhaps delayed for a few years, what sort of nukes would Britain have? I assume that Skybolt and Polaris wouldn't be on the scene.

Dathi THorfinnsson · Aug 29, 2015

Check out st-200's Selene Project, currently in process.

While the Anglo-French rocketry programme he(?) has is wildly ambitious, it does proceed from the US NOT agreeing to a sharing of nuclear resources, so Britain builds its own ICBMs, and never has a Polaris fleet.

pdf27 · Aug 30, 2015

Riain said:
WI this nuclear cooperation didn't occur, or was perhaps delayed for a few years, what sort of nukes would Britain have? I assume that Skybolt and Polaris wouldn't be on the scene.

Initially, they would have equipped the V-force with the Grapple weapons (1 tonne/1 Megatonne freefall bombs, from memory). Moving on from that, Blue Steel would probably have been developed further and there is a possibility that they would have developed a dedicated low-level bomber (a long-range equivalent to TSR.2 - this was looked at in the 1950s in OTL) as their delivery system, since ICBMs are relatively technically challenging and Blue Streak was never a survivable option even compared to bombers.
In the long run they'd probably end up with a ballistic missile submarine project shared with the French - the British were already working on submarine PWR designs when Mountbatten sweet-talked Rickover into giving him US technology lock, stock and barrel.

The interesting bit is actually the effect on US nuclear weapons - the British actually found a major safety flaw in the then-current US designs which was corrected as a result (in a major piece of re-engineering). If they hadn't done so, it's interesting to speculate as to what sort of accidents might have occurred.

Riain · Aug 30, 2015

It would be interesting to see how the British warheads came out, from what I can tell even the US designs they used were changed to better meet British circumstances. Perhaps they would be of lower absolute performance, but simpler, more reliable, safer and easier to maintain in service for long periods.

PMN1 · Aug 30, 2015

pdf27 said:
The interesting bit is actually the effect on US nuclear weapons - the British actually found a major safety flaw in the then-current US designs which was corrected as a result (in a major piece of re-engineering). If they hadn't done so, it's interesting to speculate as to what sort of accidents might have occurred.

What were the flaws?

Riain · Aug 30, 2015

The British weren't happy with the US explosives, they thought they were too sensitive, brittle and prone to other problems. They used the W28 was the only US warhead they used as-is, after that they developed their own primaries.

marathag · Aug 30, 2015

Riain said:
Perhaps they would be of lower absolute performance, but simpler, more reliable, safer and easier to maintain in service for long periods.

Any design that relies on Tritium and Plutonium need to be continually reworked.

asnys · Aug 30, 2015

Riain said:
The British weren't happy with the US explosives, they thought they were too sensitive, brittle and prone to other problems. They used the W28 was the only US warhead they used as-is, after that they developed their own primaries.

They were right, too. Developing more reliable conventional explosive triggers was a significant part of US nuclear weapons development in the second half of the Cold War.

asnys · Aug 30, 2015

marathag said:
Any design that relies on Tritium and Plutonium need to be continually reworked.

You can build a hydrogen bomb using only uranium, though it will be lower performance. And tritium isn't that big a deal - it's just a matter of swapping out the tritium bottle periodically, not of refabricating components.

Dathi THorfinnsson · Aug 30, 2015

marathag said:
Any design that relies on Tritium and Plutonium need to be continually reworked.

If by that you mean that Tritium decays, and becomes less effective after a few years, yes. You have maintenance that needs to be done.

But your mention of Plutonium severely confuses me. It has a half-life orders of magnitudes longer than any weapon. (assuming you mean Pu239, which is what you want for your weapons).

pdf27 · Aug 31, 2015

I've got a very sketchy memory that it wasn't just the explosives - the British H-bomb designs were apparently a Fission-Fission-Fusion design, with the second Fission stage requiring the first to trigger it and only the second Fission stage being powerful enough to trigger the Fusion stage. As I understand it they also used an odd variant on Teller-Ulam, with the Fusion stage being spherical rather than cylindrical.

This is all unfortunately rather vague, however - a lot is still secret and there are a couple of books on my wish list (mostly by Lorna Arnold) that go into it in some detail. Unfortunately right now I have no space for more books in the house (may well be moving in a few months, depending on jobs) so have been banned from buying more.

Riain · Aug 31, 2015

Orange Herald was a layer cake bomb, with a fission pit surrounded by fusion lithium which was surrounded by natural uranium I think as a further fission layer. This is not a Teller Ulam design, although I think the final grapple tests were of this primary-secondary design. Certainly the designs Britain got from the US were Teller Ulam.

Another particularly British thing that may need to be worked around is the lack of fissile material, so perhaps Britain might put more work into Uranium-Plutonium composite 'pits' than the US did.

pdf27 · Aug 31, 2015

Riain said:
Orange Herald was a layer cake bomb, with a fission pit surrounded by fusion lithium which was surrounded by natural uranium I think as a further fission layer. This is not a Teller Ulam design, although I think the final grapple tests were of this primary-secondary design. Certainly the designs Britain got from the US were Teller Ulam.

Not Orange Herald, the memory I have is that it was the Grapple Z design that had the spherical secondary.

Simon · Aug 31, 2015

pdf27 said:
The interesting bit is actually the effect on US nuclear weapons - the British actually found a major safety flaw in the then-current US designs which was corrected as a result (in a major piece of re-engineering). If they hadn't done so, it's interesting to speculate as to what sort of accidents might have occurred.

pdf27 said:
As I understand it they also used an odd variant on Teller-Ulam, with the Fusion stage being spherical rather than cylindrical.

That's actually what I was going to mention in reply to your earlier post about it not all being a one way street. The US had tube shaped secondary whilst the British had developed technically more challenging spherical one which had benefits such as the amount of space taken up when fitting them to missile warheads or looking at multiple independently targetable re-entry vehicles (MIRVs). Once co-operation was started back up again whilst the US was generally pretty generous with information they wouldn't give it away free of charge so the British always made sure to carry out their own research projects such as the Gaslight and Dazzle Black Knight re-entry tests so that they would have at least something to trade even if they generally got more out of the deals.

Riain · Sep 1, 2015

Does anyone have a diagram of the spherical secondary? Does it have a sparkplug? Is it more economical on fissile material as well as space?

BlueTrousers · Sep 1, 2015

Simon said:
Once co-operation was started back up again whilst the US was generally pretty generous with information they wouldn't give it away free of charge so the British always made sure to carry out their own research projects such as the Gaslight and Dazzle Black Knight re-entry tests so that they would have at least something to trade even if they generally got more out of the deals.

As I understand it, the post-GRAPPLE British and American nuclear weapons programs are so closely intertwined that there's effectively a single joint program, with all American devices containing significant British input.

Riain · Sep 1, 2015

The 3DQP the British developed for the Chevaline was subsequently used in US RVs, so the street does go both ways.

Mumbles · Sep 1, 2015

Riain said:
Britain only bought into service 3 nuclear weapons of its own design; the Blue Danube, Green Grass and Red Beard. These were all basic fission weapons, in the case of Green Grass a real whopper and very unsafe and difficult to handle in service conditions.

Does the WE.177 not count?

BlueTrousers · Sep 1, 2015

Mumbles said:
Does the WE.177 not count?

The primary was UK-designed, but the secondary was derived from the US W59. Arguably that makes the WE.177A a British design.

Download · Sep 1, 2015

Riain said:
Does anyone have a diagram of the spherical secondary? Does it have a sparkplug? Is it more economical on fissile material as well as space?

Given you have neutrons coming straight off the core of the weapon to fission Li-6 into tritium you probably don't need a sparkplug.

The reason they wouldn't use it in modern weapons is because to scale it you need to make the weapon far fatter.

Edit:

Are we talking about a spherical layer-cake weapon?

There are probably also secondary compression problems. In a standard design you have ablation pressure compressing the secondary from nearly every side. In a layer-cake design you only have pressure on the inner side and rely on the other side's inertia to compress the 'secondary' part.