Say a 7 rated disaster like Chernobyl and Fukushima, how was the Chernobyl sarcophagus built? How did people work so close to the exposed cores and can an NBC suit protect from that level of exposure to nuclear radiation and that extreme proximity to them?
Lightly googled this but didn’t find anything
In: Physics
Chernobyl is not Fukushima!
Good reactors are built inside a containment, so there is no need to build something afterward. Chernobyl was rediculously unsafe.
The Chernobyl sarcophagus was built quickly, and without regard to the long-term. Containing the catastrophy was paramount and there was little time to spare. Workers immediately went to the roof and began shoveling debris into the core in an attempt to extinguish it, and aircraft came overhead to dump clay and sand into it. Then, liquid nitrogen was pumped under the core in an attempt to cool it via a tunnel. It was covered with concrete, over the course of seven months, and it was not done safely: 31 died of acute radiation poisoning.
Recently, a new concrete sarcophagus was built over the old one it was built hastily and flawed. It was close to collapse and was itself radioactive, and the new sarcophagus is designed to last about 100 years.
Fukushima’s cleanup is still ongoing, but workers are either working in short increments in protective suits (the suits can’t protect after some period of time) or using robots to do it.
It’s a pretty multifaceted subject, so if you’re curious about something specific I can probably dig it up for you.
> How did people work so close to the exposed cores
Robots couldn’t operate near the reactors without being destroyed due to the high radiation levels so they used humans instead.
Radiation exposure is directly proportional to how much time you spend near the reaction + proximity to it. The USSR sent in waves of ‘human robots’ to clean up the radioactive material surrounding the reactor. Limiting each individuals exposure to the most intense radiation to less than a minute. Then cleaned them up and sent them home.
Basically they determined that a human could operate near the reactor for a set period of time without causing too much damage. But basically what it boils down too is the Soviet Union didn’t care that much about human lives, and they had no other choice.
> can an NBC suit protect from that level of exposure to nuclear radiation and that extreme proximity to them?
No, not really. An NBC suit will protect you from a different problem.
The Gamma radiation put out by the reactor core is too intense. You need very thick shielding to protect people from it. Steel + lead + concrete.
An NBC suit will protect you from the radioactive dust or fallout. The explosion of the reactor and the resulting fire put large amounts of radioactive particulates into the air. This is what the NBC suit really protects against.
This dust quickly decays into safer elements, and within a few weeks of the fire being put out much of the dust had decayed and was now harmless. This is why you see people being washed and their clothes removed during movies about nuclear attacks. It’s about getting rid of the radioactive dust.
> How is an exposed reactor core in a nuclear meltdown situation contained and cleaned up?
When a reactor melts down the radioactive material in the core melts the reactor vessel producing a type of lava dubbed corium.
Corium is super heated and burns through just about anything it touches, hence the term melt down. It takes a long time for to cool down adequately to no longer be a significant threat, so it has to be contained.
In a Western reactors the reactor is built above a large concrete containment vessel. Basically a large reinforced concrete pit. During a meltdown the Corium falls into this pit and is contained. It can then be sealed off with relative safety.
In RBMK reactors the Soviets didn’t build adequate containment vessels because they were cutting corners. At Chernobyl they were force to mine underneath the reactor and pour in tons of concrete to make a containment vessel after the fact to prevent the corium from hitting the water table.
There’s a doc on Netflix that goes into some of this. I forgot the name though but it’s fairly new.
When it comes to Chernobyl people were basically exposed to high amounts of radiation, but you have to keep in mind the Soviet government didn’t really care. The sarcophagus was built over a period of months and was very unstable. The building wasn’t sealed as radiation was too high and they weren’t even sure if the roof would hold up over the harsh Ukrainian winters. Fukushima on the other hand did not blow up, at least the cores didn’t. Some of the rooms under the reactors are up to 530 sieverts an hour (8 sieverts in a short amount of time is fatal and even lower can be fatal without treatment). That’s why the Japanese government is using robots to clean up the fuel. Another thing to note is that there is a lot of fuel in reactors. The melted fuel of Chernobyl hasn’t and probably won’t be moved for a long time because of radioactivity, but also because there’s many tons of fuel that would be very hard to move. The plastic suits you see Fukushima workers wear won’t protect from gamma radiation and probably not beta either, but it would prevent you from getting a piece of dust emitting alpha radiation from getting on you or in you. Alpha is very heavy and basically just a helium nucleus without electrons. It can’t penetrate your skin, however if you breathe it in your risk of cancer will go up significantly. Another thing to note is that the containment buildings for the reactors at Fukushima are 3-4 feet thick concrete, which blocks quite a bit of radiation. The Soviet RBMKs have no containment unit around the vessel. All in all, nuclear meltdowns are a big pain but extremely rare and if dealt with properly will result in few health effects to humans.
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