What type of maintenance must nuclear weapons go through. I know they don’t just last forever but why? What goes “bad” with them just sitting in storage
Not an expert in the field, but a few things come to mind:
-the fissile material, being radioactive, undergoes radioactive decay. After some period of time, the composition of the material may change enough so that you don’t get the big bang you really wanted.
-the high explosives may undergo chemical decay over time, necessitating periodic replacement.
-any on-board batteries may go bad over time and need replacement.
-random electronic components may crap out over time, whether they’re in use or not. For example, I know that tin whiskers have been a problem on some military (and other) hardware in the past.
Would be curious to hear from an expert in the field.
Tritium is a common component in modern nuclear weapons. It decays over time and needs to be replenished.
As always, Wikipedia is a good place to start.
Bottom line: nuclear weapons are complex systems with many sensitive parts comprised of exotic materials manufactured to precise tolerances. The warheads get deployed out in the middle of nowhere, not always in climate-controlled environments.
This is one of the reasons testing is considered so important. It’s not a case of knowing whether the weapon designs work or not-- in 2009, the U.S. is pretty confident of that-- it’s a case of knowing that when you take a warhead off an ICBM, SLBM, an aircraft, or an artillery piece, you still get a reliable detonation. Sometimes the warhead won’t go off, or it will “fizzle”, i.e. detonate with less than the desired explosive force.
The reason why this knowledge is important is to maintain a credible deterrent. If we’re confident our weapons will work when launched, the bad guys will be confident they will work when launched, and (theoretically) be less likely to attack.
Of course, the U.S. stopped testing, in 1992. Since then, the U.S. has relied on data collected previously to forecast warhead lifetimes, as well as computer models. The new National Ignition Facility that just went live in California was explicitly constructed to generate miniature nuclear fusion events to model nuclear weapon explosions, since the U.S. no longer tests live weapons. As a bonus, if it works as planned, the NIF will have a lot of peaceful applications as well, including for research on generating sustainable fusion power.
(Oh, and everything Joe said above!)
A slight tangent, and a very good short story: The Long Watch - Wikipedia
Electronic devices are susceptible to failure, especially if exposed to a range of environmental conditions. Hence the proposal to put live chickens inside the Blue Peacock nuclear mine.
Hah. Even more of a tangent, but I thought you meant this.
Joe Frickin Friday and davekphs have already provide most of the answers to this. Reliability with age is generally addressed by what is called an aging surveillance program; that is, vary components or subarticles are regularly inspected or tested for age-related defects due to chemical breakdown or latent reactions, corrosion, et cetera. In particular, reactive elements (general ordnance, electric bridgewire detonators, shaped explosive blocks, thermal batteries) are tested by lot sample to assure statistical reliability within defined parameters. Other components like safe & arm devices and other electromechanical interlocks (especially on older weapons) have to be verified that working surfaces aren’t corrosion-fused together or otherwise nonfunctional.
The fairly unstable tritium used in boosted fission and thermonuclear fusion devices has to be periodically replenished, and components exposed to ionizing radiation tested to assure that no detrimental structural or electrical defects have occurred. While the main nuclear material is not replaced unless damaged, uranium-235 is problematic for long-term usage as it’s primary decay product, the alpha particle (essentially a helium nucleus) may create interstitial cracks in the solid material and absorb neutrons, rendering the weapons both potentially unstable (though not dangerously so) and prone to fizzle.
Plutonium-239, a gamma emitter, doesn’t suffer from this problem, but it does decay (albeit slowly) into [sup]235[/sup]U. However, all [sup]239[/sup]Pu also has some fraction of [sup]240[/sup]Pu, which tends to be a neutron absorber. This creates [sup]241[/sup]Pu, which decays into Americium-241, which then decays releasing an alpha particle and has a variety of decay chains that are undesirable in terms of long term stability. [sup]240[/sup]Pu also has a larger neutron cross section than [sup]239[/sup]Pu, and plutonium as a metal is prone to a variety of solid state phase transitions which may make it unstable. Modern Naval SLBM warheads used super-purified plutonium (no more than 2-3% [sup]240[/sup]Pu) to ensure reliability.
The lack of an ongoing test program for the nuclear material itself means that computer simulation models based upon our current understanding of the interrelationships between all of the chemical and nuclear interactions going on is our only way to guestimate the reliability of the core of the weapon. Although we have a pretty good grasp and extensive test history, this still leaves the possibility of some poorly understood long-term phenomenon that may cause the weapon to be unreliable. Some small-scale non-detonation testing supplements known data, but it’s obviously not the same thing as putting one in a big hole in the ground and lighting it off.
Another consideration not considered above is the physical security and storage of nuclear weapons. For obvious reasons you can’t just stick them in a large warehouse in a crate marked, “Manuals, Metric Conversion” or “Ark of the Covenant, Lost” and leave it at that. The security on nuclear weapons–which both has to be unadvertised and yet highly assured–is a substantial cost of maintaining weapons. Aside from the physical security–which unlike much of the security on military bases is performed by military or Department of Energy personnel, not private contractors–there are large amounts of paperwork, much of it secure, which has to accompany the arrival and deployment of nuclear weapons or material. Notable failures in this regard result in extreme, often career-ending penalties, and so it is generally taken extremely seriously, with the corresponding effort that goes with that.
Although I don’t know if this occurs with nuclear weapons, most weapons systems undergo regular upgrades and improvement programs to enhance reliability and remediate any original design defects. Since there are no ongoing nuclear weapon design programs except the Reliable Replacement Warhead, I don’t know that there are any significant upgrade programs for existing nuclear systems, although there are certainly sustainment programs at some level.
The ongoing cost of sustaining a large (though much decreased) strategic nuclear arsenal begs the question of why we are maintaining such a capability. In the post-Cold War, multi-player environment the concept of Assured Destruction as an effective system of deterrence from attack is highly questionable at best. While maintaining a smaller arsenal for “flexible response” against regional threats is probably in the cards for the foreseeable future regardless of the protests of nuclear disarmament, strategic-class weapons without a target or identifiable threat seemed to be not much more than a very expensive and not just slightly dangerous peacock tail.
Stranger
http://www.wagingpeace.org/articles/2004/05/06_cipolat_weapons-price.htm Maintaining our arsenal is pegged at 6.5 billion a year. 18 million bucks a day.