Nuclear power plants need a way to cool the water that cycles through the reactor and generators. Some use cooling towers, but most rely on the water located nearby – a lake, a river, or… the Pacific Ocean.
Fukushimu is a large city in Northern Japan quite a bit inland. Fuushimu Nuclear Power plant is the one that is probably currently having a core meltdown and exploded. There isn’t a lot in a nuclear power plant that would explode except steam, or possibly hydrogen, or a long shot – the diesel fuel for the generators.
Fukushimu Nuclear plant is right on the Pacific Ocean – right at the point where the Tsunami would have hit.
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From the time of the earthquake, they had about half an hour to start shutting down the reactor before the tsunami hit (they would have no way of knowing that time frame). When the tsunami hit, they lost their diesel generated electric power, losing the ability to pump water through the coooling system and control the plant – so here we are.
One scenario I can make in my mind could be… the earthquake caused the reactors to go into SCRAM mode – upon losing power or detecting an emergency, the control rods all fall into the reactor core to immediately stop the nuclear reaction. This is part of the “failsafe” design – if something has gone horribly wrong and the operators are all dead, nobody is controlling the plant, they have lost operational control – by design the reactors SCRAMs and shuts down by itself.
Unless somebody says to themselves…. OMG – the city of Tokyo is going to lose power with all these reactors going offline – restart them now!!!! “But our training says you should never do that!”… “F*ck you training!- just do it!”…. “But what about the risk of a Tsunami?”…. “That’s my responsibility, just do it!”….
Okay – you’re the boss….. [lift control rods and end SCRAM mode]
[… 20 minutes pass…]
**** Splash ****
**** Bang *****
[Darkness in control room]
“Oh Crap”…
How will this affect our nuclear program. Trick question. The answer is “what nuclear program.” I think all this will do from our point of view is reinforce the “nuclear is bad” mantra the environmentalists have been uttering since Three Mile Island.
Coal, anybody?
The reactors scrammed as designed due to the initial earthquake shock, or more likely due to loss of the electrical grid itself. Most of the plant non-safety auxiliaries require power from the external grid to work. There would have been no reason to order a restart because the grid was down- that would have been obvious. Besides which, you don’t just flip a switch to restart a nuclear plant after a reactor trip. Similar to a NASA launch it takes hours of surveillance tests and system checklists to be completed before you’re ready to restart.
What obviously bit them was the enormously powerful earthquake that may have been outside the plant design basis (some TEPCO officials are quietly reporting to the US NRC that they recorded a 9.1 Richter scale reading at the plant site), followed by the tsunami of biblical proportions that was totally outside their design basis. No reasonable engineer plans for that level of destruction- if he did he’d be fired. [Of course they will now, now that it’s actually happened.] But no matter how well you maintain your emergency diesel generators you can’t start them when they are underwater. Ask any WWII submariner. :-)
Bottom line is that this will either be nuclear power’s “Apollo 13 finest hour”, or as Art says, we better get used to a coal/oil “Cap & Trade” government-managed energy future. Pray for the Japanese engineers. Our technological future is in their hands.