41–50 of 66 posts
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It has been ∞ years since a tsunami washed away this stone.
It should also include the location of where the stone lived before the tsunami. That would help future archaeologists determine how big the tsunami was
Fun facts, Fukushima Daiichi Nuclear Power Plant was built beyond the warning limit of the tsunami stones. If those people that setup the tsunami stones are still alive during the incident they will have a kahuna of "I told you" moment.
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Another option is designing fail safe reactors. CANDU reactors designs are over 60 years old now and were built fail safe so that if outside power to the core is cut off the system would safe itself by dropping control rods which are held up by electromagnets into the core.
A reactor scram isn't necessarily enough -- you still have decay heat to worry about. In the case of Fukushima, the fission chain reaction was stopped but without cooling pumps the decay heat was still too much.
For light water reactors this basically just amounts to a large pool up a nearby hill or in a water tower.
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A reactor scram isn't necessarily enough -- you still have decay heat to worry about. In the case of Fukushima, the fission chain reaction was stopped but without cooling pumps the decay heat was still too much.
It seems like you should build a water reservoir at a higher elevation than the core and then apply a similar principle where valves regulate the water stream, but if the valves lose power they fail open. The reservoir can be built so that there is always enough water to cool the core. For light water reactors this basically just amounts to a large pool up a nearby hill or in a water tower.
Earlier quoted context omitted.
It seems like you should build a water reservoir at a higher elevation than the core and then apply a similar principle where valves regulate the water stream, but if the valves lose power they fail open. The reservoir can be built so that there is always enough water to cool the core. For light water reactors this basically just amounts to a large pool up a nearby hill or in a water tower.
there are reactor designs that work that way, but most civilian power plants are pressurized water reactors. it is important that the water stays pressurized or you get a chernobyl
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‘How old are these buildings?’ would be wise to consider. This probably works for a variety of things and in many places.
Japan has a bad habit of considering buildings as disposable. Odd that a land with 1000 year old temples knocks down 40 year old houses with zero remorse, but that seems to be the case.
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A reactor scram isn't necessarily enough -- you still have decay heat to worry about. In the case of Fukushima, the fission chain reaction was stopped but without cooling pumps the decay heat was still too much.
It seems like you should build a water reservoir at a higher elevation than the core and then apply a similar principle where valves regulate the water stream, but if the valves lose power they fail open. The reservoir can be built so that there is always enough water to cool the core. For light water reactors this basically just amounts to a large pool up a nearby hill or in a water tower.
Even when you correctly shut down the chain reaction in the reactor (which correctly happened in the affected Fukushima powerplant) a significant amount of heat will still be generated in the reactor core for days or even weeks - even if it was just 1% of the 3 GW thermal load, that is still 30 MW. It will be the most intense immediately after shutdown and will then trail off slowly.
The mechanism for this is inherent to the fission reactors - you split heavier elements into lighter ones, releasing energy. But some of the new lighter elements are unstable and eventually split to something else, before finally splitting into a stable element. These decay chains can take quite some time to reach stable state for a lot of the core & will still release radiation (and a lot of heat) for the time being.
(There are IIRC also some processes where neutrons get captured by elements in the core & those get transmutated to other, possibly unstable elements, that then decay. That could also result add up the the decay heat in the core.)
And if you are not able to remove the heat quickly enough - the fuel elements do not care, they will just continue to heat up until they melt. :P
I am a bit skeptical you could have a big enough reservoir on hand to handle this in a passive manner. What on the other hand I could image could work (and what some more modern designs include IIRC) is a passive system with natural circulation. Eq. you basically have a special dry cooling tower through which you pass water from the core, it heats up air which caries the heat up, sucking in more air (chimney effect). The colder water is more dense, so it sinks down, sucking in more warm water. Old hot water heating worked like this in houses, without pumps.
If you build it just right, it should be able to handle the decay heat load without any moving parts or electricity until the core is safe.
I've always been fascinated by these because I love long term thinking. What current "tsunami stone" would you leave to future generations to prevent catastrophe?
With radiation half lives what they are, our society should be brainstorming how to segregate and mark nuclear waste storage areas. All areas that store radioactive waste. Without clear warnings and boundaries humanity is just waiting for a catastrophe. A tiny sign and words don’t count.
https://www.ans.org/news/article-416/the-art-of-the-10000yea...