But how do the first ones fail? The answer is that lack of decay heat removal allows the earlier barriers to heat up, melt, and fail. Well, if you have an intimate connection to an infinite heat sink (the sea), you don't ever lose decay heat cooling. You can't! So your fuel and clad stay intact in almost all scenarios.
Earthquakes? No problem, the sea buffers you. Tsunamis? No problem, stay in moderately deep water and the wavelengths are so long that you'll barely notice them. Heavy weather? The world's largest ship (Prelude) is designed to stay operating (it's a LNG facility) during Cat 5 cyclones. Military attack? Sink and cool passively until a designed recovery operation can occur Ship collision? Stay out of shipping lanes; worse case, sink and don't leak.
Also, keep people out of your exclusion zone by being a few km offshore.
Honestly it's a pretty slick low-carbon rapid deployment scenario that improves construction cost and safety. Operation will likely be more expensive, but maintenance maybe not (since you can go home to the shipyard and be relieved by a spare).
Love the "sink and don't leak" requirement.
Nuclear accidents generally worry about something called Large Early Release Frequency. Some of the most bioactive/dangerous fission products decay away in a few days. This kind of scenario completely eliminates those FPs from concern, though we do still have to worry about the longer-lived ones.
This isn't hypothetical. This list may interest you: https://en.wikipedia.org/wiki/List_of_sunken_nuclear_submari...
>... the ocean is full of salt, how many half-lives until corrosion prevents containment?
quoting you:
>They have not corroded away and released wholesale nuclear waste after many decades. If that's not relevant to your line of inquiry then I must be totally misunderstanding you.
You don't misunderstand me, you purpousely misinterpret my questions so you can give easy answers...
I-131 has an 8-day half-life and is the primary threat to populations in large early releases. The direct answer to your question for I-131 is at least 2,000 half-lives. Sr-90 and Cs-137 have 30-year half lives, so for them it's at least 2. As you surely know, the longer half-life nuclides release energy more slowly and are therefore less dangerous to biological systems. At the extreme, U-238 has a few billion year half-life and can be handled safely without shielding.
In the scenario I'm painting, the reactor would be recovered from the sea within ~5 years so none of this matters. The corrosion will not fail the system within those 5 years. I do not propose to just leave any failed reactor down there indefinitely.
>Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith.
Which is exactly what I was accusing you of before you reflected the accusation. Please note there are 2 components in this rule:
1. Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize.
2. Assume good faith.
I will discuss part 1 in the context of our discussion, but first point out that 2: does not mandate to keep and maintain the a priori assumption of good faith, it only mandates to assume good faith.
Now for part 1, lets personally dissociate and review the discussion as being held by Alice and Bob:
After Bob states,
>Better stated: sink and don't leak because you are intimately linked to a near-infinite heat sink, and heating up/melting are a prerequisite to leaking.
Alice asks a concise question:
>that doesn't discuss corrosion though, the ocean is full of salt, how many half-lives until corrosion prevents containment?
and later Alice adds the question:
>is that assuming steel at the same temperature as the surrounding salt still water, or assuming steel that is hotter than the constantly convecting stream of fresh salty water?
All the while Alice is a priori assuming good faith on behalf of Bob.
Now Bob can give multiple interpretations to Alice's question, and he is required to please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize.
Bob can use interpretation 1 interpreting Alice as Alice1 implying all of the following:
* 1A) Alice is worried about shortlived isotopes
* 1B) moreover she seems to believe steel corrodes in a matter of days in the salty sea, Alice probably never heard of the Titanic recovery, Alice believes that ships can't be reused because after every trip they are decommisioned and a new ship is built for every trip.
* 1C) Also Alice seems to be unaware that Iodine is the most easily mitigated isotope since we can bulk manufacture Iodine tablets containing non-radioactive isotopes.
* 1D) Alice seems to be uninformed about all the above topics despite referencing concepts like nuclear half lives, the corrosion of metal in salty water, convection of hot water in cold water, and the concentration and saturation of metal ions in aquaous solutions...
This interpretation of Alice is easy to criticize, for obvious reasons
or Bob can use interpretation 2 interpreting Alice as Alice2:
* 2A) Alice is worried about longlived isotopes
* 2B) Alice is worried about the influence of energy release in the long tail of nuclear decay: consider a simple system of N identical unstable isotopes decaying to a stable isotope (thats ignoring the worse long decay chains), after one half life, half the number of remaining radioactive particles has halved, but half of the energy that will eventually be released as heat (not temperature!) is still contained in that long tail. Alice wonders if that energy can speed up the corrosion process on long time scales. When salty water dissolves metal, theres a thin layer of water that is saturated by dissolved metal which acts in a self-limiting way. But if the heat causes convection, that thin layer of saturated water will be constantly replenished with fresh unsaturated salty water. Similarily evaporation is much enhanced if convection or wind carries away the saturated air, which is why we like to hang our clothes to dry outside...
If Bob chooses interpretation 1 (which is easier to criticize) over interpretation 2, then it is Bob who is acting in violation of part 1 of the rule from the guidelines...
If Bob then at some point replies "They have not corroded away and released wholesale nuclear waste after many decades." Then Alice can only conclude that Bob has chosen the weaker interpretation Alice1 over Alice2. At that point she simply corrects her a priori assumption that Bob is acting in good faith, and she explicitly points it out.
Then Bob escalates by reflecting the identical accusation in a vague reference to the guidelines, simply because Alice is open about her founded conclusion on Bob's behaviour, while Bob never explicitly states he chooses interpretation Alice1 over Alice2 even though it is evident to any reader... Alice did assume good faith on behalf of Bob, but Bob's replies imply he chose the weaker interpretation Alice1. That is unless Bob genuinely believes people like Alice think ships are one-time-use items, that Iodine tablets do not exist, ...
I hope someone (dang?) who can prove their association with the platform can clear this up, perhaps in your favour perhaps in mine (don't care really, I would just like clarity / precedent, so that we maintain equality before the guidelines)
*
Also you keep changing attention to a lesser problem of containment, the short-lived nuclides, for example you state:
>Nuclear accidents generally worry about something called Large Early Release Frequency.
Why are you personifying the accident events? Surely you mean nuclear experts instead of accidents? Let me explain why they focus on the short-lived nuclides: because they can be affordibly mitigated with measures like Iodine tablets. abstaining from eating produce from the affected area for a few days, etc...
The longer lived ones are not necessarily safer, they are simply not affordibly mitigatable over longer timespans! (In case of consumption, the shortlived ones have a higher activity of course, but the longer-lived ones with a lower activity would be consumed for long timespans, such that DNA damage can integrate over time)
*
Regardless of these issues, would you consider it prudent for mankind to explicitly define an absolute reference background energy-spectrum of radio-activity? i.e. for each gamma energy bin some typical but from then on fixed reference background activity? Because the only references to background I find are currently comparing with whatever local background is found away from a target of investigation, which is good enough on short timescales, but how will future generations be able to compare their background with ours? It seems we keep assuming that the natural background can not be influenced by human activity, which seems dangerously close to the original fallacy that human activity can not influence atmospheric CO2 concentration...
With that much "no problem", it seems like something may have been overlooked in your summary above.
Note: I acknowledge that you have much more expertise here than I do, but it's not translating well. OTOH, I'm receptive to actual analysis - I have a PhD and work in a model-intensive engineering field.
Here is a master's dissertation from MIT on the topic that goes into lots of good analysis: https://dspace.mit.edu/handle/1721.1/103707
What part is least believable for you? Shipyard construction being cheap? Floating nukes being safe? Nukes being safe in the first place? Nukes being low-carbon? Many of these thing sound surprising because they go against pop culture but they're interesting in that the scientific consensus is fairly opposite of pop culture on this topic.
I have no objection to the development of nuclear technology. But as I understand, what concerns people is not entirely the 'likelihood' of the disasters but rather the 'severity' of them. After all, People make mistakes and organizations corrupt. So, I think any tech progresses on the scale-down of the worst case where all safety is off would be far more helpful in convincing the public.
I think it is extremely irresonsible to build military equipment with nuclear reactors. They are destroyed in conflict, polluting everything.
https://en.m.wikipedia.org/wiki/List_of_sunken_nuclear_subma...
Of the nine sinkings, two were caused by fires, two by explosions of their weapons systems, two by flooding, one by bad weather, and one by scuttling due to a damaged nuclear reactor.
"""
(for those looking, it's to the movie The Hunt for Red October)
School shootings in the USA and ISIS beheadings don't affect my daily life, either.
Remember nuclear pressure vessels are subject to some of the most harsh conditions when in operation. They're built to withstand contact with extremely hot water under pressure. Will salt water eventually corrode through it? Maybe. But remember energy through fossil fuels and organic matter kill 3 and 4 million people per year respectively. Those concerned with nuclear safety often fall into the fallacy of letting perfect be the enemy of good. The best solution is the least-bad solution.
Seems like even in the worst and extremely unlikely scenario of full detonation, we'd still be fine.
Some Marshall Islanders would like a word[0]
[0] https://www.theguardian.com/world/2014/mar/02/bikini-atoll-n...
The explosions which happened in deep water (Wigwam in 1955 for instance) had practically zero lasting effects beyond radioactive steam entering the atmosphere.
Typical powerplant reactors operate in the TWs.
Yes, it's 1-2 orders of magnitude.
If anything, it proves that identifying all failure modes is challenging, and theoretically safe is not the same as practically safe.
Of course it is, which is why modern reactor designs have incorporated safety features based on these accidents and older designs have been retrofitted (with some exceptions that are legitimately concerning). It's entirely true that it is impossible to predict every mode of catastrophic failure, but that does not mean it's impossible to create designs that are resilient to unplanned disasters. No type of power plant can be perfectly safe, but for assessing practical safety records, in terms of deaths / TWh generated, even estimating conservatively nuclear power is safer than any other source of power (including wind and solar). Some references for this:
https://www.statista.com/statistics/494425/death-rate-worldw...
https://ourworldindata.org/what-is-the-safest-form-of-energy
https://www.nextbigfuture.com/2008/03/deaths-per-twh-for-all...
There's a handful of nuclear reactors compared to planes, and new nuclear reactor designs, where there's an opportunity to cut corners, are not being introduced at the same rate as new plane designs.
A reactor is a large, heavy, stationary thing. Economic concerns exist, but they're not going to make engineering decisions based on weight like you would in a plane where every kilogram of material costs a fortune in fuel over the lifetime of the plane. An extra chunk of concrete in a nuclear plant costs nothing, operationally speaking.
We're just lucky that the planes aren't nuclear despite many wildly ill-advised attempts to make this a reality.
There were updates suggested to modernize the facility, but for cost cutting purposes they were ignored:
https://m.phys.org/news/2011-03-iaea-japan-nuclear-quake-wik...
It always comes down to cost cutting when the accidents are rare enough.
Newer designs have suffered more major faults and managed to contain virtually all of the radiation. American designs, in particular, place great emphasis on having an extremely resilient containment structure above the reactor. A lot of things can go horribly wrong but so long as the extremely radioactive gas is contained it can later be cleaned up. These radioactive elements are extremely toxic, but also very short lived. You just need to buy time.
The Fukushima design may as well have had a tin roof, it exploded almost immediately and exposed the reactor to the elements. If that's not a design flaw, I don't know what is.
That and a number of the systems necessary to keep the reactor under control depended on poorly positioned generators that weren't flood-proofed. This seems like a major oversight on a building located in a tsunami and typhoon zone.
I think our problems with nuclear power are 95% political and maybe 5% or less technological. Canada for example has nuclear plants that use a neutron moderating coolant. If they lose coolant, the reaction stops. Unlike earlier designs where a loss of coolant lead to overheating and potential explosions. Not to mention new nuclear plants need 6-7 completely independent shutdown/safety features which is unheard of for earlier plants that have at best 1 or 2 emergency shutdown procedures that interfere with each other.
Paradoxically, a nuclear plant could be made extremely safe if it just dumped all the fuel into the ocean at the first sign of trouble.
With ulimited cooling the fuel can't melt so it will be safely contained within the rods/pellets.
Yes the radiation near to the fuel would be insane, but water is so dense it would be safe to swim around maybe 50 feet away.
There's never been a bad accident in spent fuel pools even though they contain orders of magnitude more fuel than operating reactors. This is just because it's really hard to melt something sitting in thousands of tons of water