What happens to a nuclear power plant when it melts down?

Question

How do they evacuate everyone and how fast does the radiation wave travel?

Answer 1

meltdowns usually occur by the failure of the ECCS , Melting of the core , meltdowns is mainly result when the Containment Spays and Coolant systems have certain Disturbance or malfunction. This Results in Extreme heat inside the vessel and then off course Kaboom but it doesn't actually happens as there are certain Temp Recording and Plugs inside the vessel of Fuel assembly which thereby shuts the reactor off by inducing a certain material which Deactivates and absorbs all radiation .

actually if the system doesn't work and they have to leave the site certain devices which alerts them about the pressure within the Chamber allows them of significant time they have to leave the site . the main reactor chamber is built in certain circumstances with approximately 3 levels of highly solid concrete and iron mixture once the pressure alarm goes they check the status and if the problem can be solve they have the time to clear the Chambers which will be effected .

The speed of Radiation usually depends on the point of source and its exposure to atmosphere the most critical issue is the radioactive steam which there by can collaborate and mix with air from even a single crack or point of leakage now its the fuel intensity and on the containment building how fast will it travel ( waves are there by stopped by the solid shields of vessel containers ) usually in a reasonably tight rector building the leaks per day would be less then 0.1% of the radioactive fission product gases .


have a nice day.

Answer 2

Meltdown occurs due to loss of cooling or fission reaction control rod operation. The uranium fuel simply melts. This does not *necessarily* mean there will be a release of radioactivity, since in most plants there is a superstrong containment building to prevent this. If there is not like at Chernobyl (those silly Russians!) and pressure builds up to the point of bursting the reactor, the released radioactive isotopes travel with wind.