It is a passive cooling system, once you activate it. And the activation is automated. Once it is activated, the reactor primary coolant circuit cools to a storage tank. That water boils into steam, then touches the outer wall of the containment, which cools it. The steam condenses and drips down into a collector around the containment and gets funneled back into the water storage tank. On the other side of the containment, the chimney effect will move enough air to keep the containment cooled. For the first 72 hours, water needs to be poured on to help remove heat through evaporation, after that you can keep cooled indefinately with no human interaction. it is truely a passive system.

Nuclear engineer here. Decay is not Fission. Fission is splitting the atom. Decay is the act of a radioactive atom to reduce itself closer to a stable groundstate. Fission is controllable and is directly related to neutron population, and if we stop neutron production with control rods, fission stops. Decay is not controllable, and happens all the time no matter what until the material reaches a stable ground state. All light water plants, except the AP1000, need active cooling. (The GE ESBWR doesnt need active cooling either, but its design isnt approved or even completed yet). After shutdown the core is still boiling about 600 gpm of water at 1000 pounds pressure (in a BWR). this is due to the radioactive WASTE products decaying. The fuel isn't doing anythign after shutdown, but the waste products are trying to become stable again.

a main generator of a NPP (and any other large base load plant) cannot handle small or transient loads. when you lose offsite power, you have no load, and the generator has to shut down, otherwise you could damage the generator or destroy the turbine catastrophically. equate it to riding a bike. if you are going 20 mph on a bike in first gear and you are pedaling as fast as you can it is very unstable. (there isnt enough load for the energy your legs are producing). if you are in 6th gear you'll be fine because there's enough load to counter what your legs are trying to put in. anyways...this is why there are at least 2 qualified AC circuits plus at least 2 diesel systems per plant.

all floors in nuclear power plants are posted by elevation. there isnt a 'first floor' 'second floor' 'basement'.

there is some kind of goofy DRM even if you buy it on steam. before I can play any DRM, my EA account needs to be logged in through dragon age. it's kind of shobby. Every once in a while i cant load my saved games, so i log out of the ea account and back in and it works.

it doesnt reduce radiation dose. gamma requires several feet of shielding to bring it down. the suits are just there to prevent particle contamination from getting in/on their bodies.

and the tectonic plates. its just as much their fault too ^_^

in a BWR loss of water actually slows/stops the reaction. water is used to moderate neutrons and without it you cannot maintain the nuclear reaction.

they are discussing that. they just dont tell the press about it because the press will spin it as "industry thinks their plants will have 100 mile fallouts everywhere and the chickens will mutate and become the new dominant species"

the pool of water below the reactor (in this case in the torus) is designed to quench vented steam and reduce pressure in the reactor. under normal conditions, when the reactor is pressurized, there are 2 emergency core cooling systems available to the core. The first is HPCI (high pressure coolant injection), and is an active pump meant to get water on the fuel. the second is RCIC (reactor core isolation cooling), and uses steam from the reactor to run a turbine and pump water into the core. RCIC requires only batteries....and that your suppression pool is below boiling point so it can quench the steam. If the plant had electrical power, and they had a leak or a failure of the high pressure systems, they would vent all their steam to the suppression pool and run their low pressure core spray and low pressure coolant injection systems. the plant i'm at has 3 LPCI pumps and 1 LPCS pump. these low pressure pumps are designed for flow, not pressure, and are capable of fully filling the reactor vessel in all but the worst pipe breaks (double guillotine shear in the recirc lines). and even in the worst condition, provided you still have electrical power, the water that is lost funnels down through pipes back into the suppression pool where it can get run through heat exchangers, cooled, and pumped back into the core repeatably. if you dont have power, the core has relief valves that automatically lift in safety mode without power if the core has too much pressure. this vents to the suppression pool. i dont know if the pool has relief valves or the containment, but you then would need to manually vent the containment to keep the pressure down enough to inject water in. during the accident, i believe unit 2 had too much pressure build up in the core and that stopped seawater injection for a while. they had to release the pressure to allow the pumper trucks to get water back in.

upvote this

the lines to the turbine and back are sealed. when there is a full loss of offsite power, the reactor protection system relays and isolation system relays and solonoids lose their charge. the moment that happens the reactor auto-shuts down and isolates. there are 2 sets of isolation valves, one inside the containment, and outside the containment and in the reactor building as a backup. In other words, the containment is almost completely sealed from the outside world. One major issue is the torus isnt as well protected as the containment drywell and wetwell. it sits outside the drywell containment and in this pseudo containment that isnt sealed as well. if that's leaking that could be the source.

cant get up there. the SFP if they have less than 15 feet of water in them are deathly radioactive. normally they measure temperature for the reactor water at the reactor water cleanup system piping, and the steam lines out. because the water levels arent up there it is hard to truely discern what the temperature is. as for not knowing a lot, they probably still dont have their plant process computers online otherwise they'd know most of that stuff. and because of the complexity of the electrical systems they probably dont have most of their power sources up which would give them indications. -iaane that manages a plant process computer.

the core damage probability is per year. not per hour. plants in the US are not allowed to operate with more than 1 CDF per 10000 years.

iaea says for emergency and life saving, it is ok to get 500 mSv. in the US, the moment an emergency happens everyone at the plant is authorized 50mSv instantly. If you are trying to operate or work in the plant, 100 mSv. to save life or prevent disaster 250 mSv. These numbers have been that way for years. they aren't just authorizing more and more dose, you can find those numbers in existing plant procedures.