Author Topic: No joke - A billion-dollar capacitor problem.  (Read 1989 times)

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Offline langwadt

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Re: No joke - A billion-dollar capacitor problem.
« Reply #25 on: September 30, 2019, 09:41:59 pm »
(converting nuclear material from bombs into civilian nuclear reactor fuel - a good way to get rid of them bombs)
I thought the high radioactive material for nukes was a by-product from nuclear powerplants not the other way around?

https://www.nytimes.com/2009/11/10/business/energy-environment/10nukes.html
 

Offline Bud

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Re: No joke - A billion-dollar capacitor problem.
« Reply #26 on: September 30, 2019, 10:47:57 pm »
They need to switch the operating model to a more consumer one. Why have a very expensive warhead that has to last 30 years? Why not have a cheap one that has to be replaced every 5 years. Yes, overall quality will be lower, but on the up side you can make a ton of them fast and cheap.

Having more warheads about to expire is also good for training and design refinements.
In a big organization upgrades are a massive undertaking. I can tell seemingly simple upgrade of the servers fleet 5 years is a bare minimum anyone would agree to and then the project may last 1 or 2 years. Do not ask me why, this is the way it is.
Facebook-free life and Rigol-free shack.
 

Offline Rick Law

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Re: No joke - A billion-dollar capacitor problem.
« Reply #27 on: October 01, 2019, 03:25:58 am »
From the article, this is a warhead refreshment project.  So, it sounds like the capacitor issue is with the warhead and not the missile.  With multiple warheads per missile, that just made the problem that much worst.

As I contemplate the headache this must be causing...  Something else came to mind...

A few years back (2014, TV show 60 minutes), there was a segment on the US Air Force still using 8-inch floppies in part of the ICBM launching sequence...  I wonder how healthy are the capacitors in those floppy drives.  Gotta be a bit puffy by now.  That could be our next billion dollar floppy upgrade initiative...

Link: https://defensesystems.com/articles/2014/04/29/af-8-inch-floppies-icbm-launch.aspx



 

Offline helius

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Re: No joke - A billion-dollar capacitor problem.
« Reply #28 on: October 01, 2019, 03:40:49 am »
I thought the high radioactive material for nukes was a by-product from nuclear powerplants not the other way around?
Weapons-grade material is lower in natural radioactivity compared with fuel-grade material (or natural uranium ore). This is important because you don't want the radioactive decay process causing criticality accidents in your highly enriched, dense bomb cores.
Plutonium is made in reactors, but calling it a "by-product" is a little misleading. The first working reactors were purpose-built to breed plutonium and didn't generate useful electrical power. Power generation came later—in some sense nuclear energy is a by-product of weapons development.
 
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Offline Whales

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Re: No joke - A billion-dollar capacitor problem.
« Reply #29 on: October 01, 2019, 04:01:29 am »
Why have a very expensive warhead that has to last 30 years? Why not have a cheap one that has to be replaced every 5 years.

30 years isn't just a technical/operational/warfare decision.  It's also a decision to work around social and government/military structural issues.

Funding dries up?  Political scandals?  Government or military collapse?  During these periods the weapons would still be considered "needed" by countries like the US, but they may not have funding or organisational ability to quickly create new ones.

N.B. a warhead full of RIFAs may break some conventions regarding specificity of bombing :P


Offline zl2wrw

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Re: No joke - A billion-dollar capacitor problem.
« Reply #30 on: October 01, 2019, 08:12:28 am »
(converting nuclear material from bombs into civilian nuclear reactor fuel - a good way to get rid of them bombs)
I thought the high radioactive material for nukes was a by-product from nuclear powerplants not the other way around?

https://www.nytimes.com/2009/11/10/business/energy-environment/10nukes.html
From a technical perspective, of all the uranium atoms in uranium ore dug out of the ground, about 0.7% is U235 which is "fissile" and the other 99.2% is U238 which is not fissile, but is "fertile" - that is, it can undergo "transmutation" by neutron capture yielding Plutonium isotope 239 (Pu239).

Some heavy water moderated (eg CANDU) or graphite moderated (eg Hanford B) reactors can run on unenriched uranium fuel, but generally speaking, light water moderated reactors (ie most of the world's civilian reactors) require the uranium to be enriched to about 3% to 5% U235 content. If you want to make a "Little Boy" gun-type atomic bomb (what was dropped on Hiroshima), then you require something like +90% U235 content in the fuel. Uranium is enriched by separating the U235 atoms from the U238 atoms, typically with centrifuges and the uranium in the form of Uranium Hexafluoride gas (a U235 atom is three neutrons lighter than a U238 atom). Uranium enrichment to +90% for bomb fuel is really hard, expensive work, and U235 has a rather high critical mass so you need quite a lot of it to make a bomb. On the other hand, Pu239 has a critical mass about an order of magnitude smaller than that of U235 and is cheaper "per bomb" to produce, but the NRE costs are higher (plutonium implosion bombs are much more complex).

When you fission U235/Pu239 in a reactor, it releases neutrons, and some of the U238 in the fuel gets transmuted into Pu239  (remember that you start with fuel that is something like 5% fissile material and 95% U238). Pu239 is fissionable, and can be used either as reactor fuel, or as the fuel for an implosion type atomic bomb (what was dropped on Nagasaki, and what is used as the initiator for thermonuclear fusion aka "Hydrogen" bombs).

However, bomb-grade Pu239 is harder to manufacture than reactor grade Pu239. Basically, in a civilian power reactor, you fission the fuel for a year or two until the build up of fission products tends to absorb so much of the neutron flux that the fuel losses "reactivity" (kinda like a battery going flat). Then you pull the spent fuel from the reactor, replace it and repeat. To a certain extent the spent fuel can be recycled (separate the unfissioned Uranium/Plutonium from the spent fuel for reuse and send the waste fission products to high level waste disposal).
On the other hand if you are seeking bomb-grade plutonium, then you don't want much "burnup" in the reactor (fuel only in the reactor for weeks or months before plutonium extraction processing) to ensure that the Pu239 doesn't get excessively contaminated with heavier plutonium isotopes like Pu240 which tend to reduce the yield of a nuclear bomb by prematurely initiating the reaction before the fuel is fully compressed. It is really really hard to separate Pu239 from Pu240 (much harder than separating U235 from U238), and spent high-burnup fuel is really hard to handle because it is very strongly radioactive because of all the fission products in it. Also, Pu239 that is contaminated with short half-life fission products is kinda hard on all the troops that have to handle the weapon containing it (the idea is to threaten to irradiate the enemy, not your own forces!).

My understanding is that most weapons grade Pu239 has come from low-burnup "weapons production" reactors like Windscale and Hanford B, oh and also from frequent online refuelling of RBMK reactors (which have a notorious reputation because of what happened in the 1980's in what is now Ukraine...)
https://en.wikipedia.org/wiki/RBMK
« Last Edit: October 01, 2019, 08:16:39 am by zl2wrw »
 

Offline duak

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Re: No joke - A billion-dollar capacitor problem.
« Reply #31 on: October 01, 2019, 05:55:52 pm »
I'd endeavour to design a nuclear weapon that would be useable for 30 year and won't go off by itself.  I'd also design it so that something has to be refreshed every month or so such that if it's lost, stolen or abandoned, it can't go off.  Sure as shootin',  someone will figure out  or accidently discover a way to cause damage.  Read https://en.wikipedia.org/wiki/1980_Damascus_Titan_missile_explosion

About nuclear fuel - The Canadian CANDU power reactor can be refueled while online so it's possible to cook U238 for a week or two without shutting down.  I understand India used this feature of CANDU for the fuel for their bombs.  Just throw a couple more on the barbie for those blokes...

  https://www.theglobeandmail.com/opinion/editorials/canada-and-india-the-nuclear-genie-40-years-on/article23978162/

 

Offline rrinker

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Re: No joke - A billion-dollar capacitor problem.
« Reply #32 on: October 02, 2019, 08:40:55 pm »
Best thing is not to build any warheads  :)

 They aren't building new ones, they are more or less recapping the existing ones to keep them in service longer. Instead of building new ones.
 

Offline Kjelt

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Re: No joke - A billion-dollar capacitor problem.
« Reply #33 on: October 21, 2019, 09:53:41 am »
A few years back (2014, TV show 60 minutes), there was a segment on the US Air Force still using 8-inch floppies in part of the ICBM launching sequence...  I wonder how healthy are the capacitors in those floppy drives.  Gotta be a bit puffy by now.  That could be our next billion dollar floppy upgrade initiative...
They have listened to you and replaced them with ssd  :)
https://www.c4isrnet.com/air/2019/10/17/the-us-nuclear-forces-dr-strangelove-era-messaging-system-finally-got-rid-of-its-floppy-disks/
 


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