I am sure there was damage from the earthquake. This 40 year old facility was designed with an antiquated knowledge of earthquake dynamics. I'm sure there were seismic upgrades through the years, but it's much harder to upgrade, and cost often trumps necessity.
All large projects suffer from delayed preventive maintenance. Any time you want to save money, yank it from maintenance. TEPCO has a past history of falsifying records and skipping inspections.
The before and after pictures show a lot of tsunami damage to the facilities between the main building and the ocean. That could have been vital equipment.
All of that happened in the first hour. I believe that everything that has happened past that point is largely influenced by human failures.
It didn't take too long to realize that significant damage to the mechanical and electrical structure was caused by the tsunami. Work should have begun at that point to pump the water out and start repairing water related damage. By Saturday morning I would have had spare pumps coming my way.
In another setback, the plant's operator said Monday it had just discovered that some of the cooling system's key pumps at the complex's troubled Unit 2 are no longer functional — meaning replacements have to be brought in. Tokyo Electric Power Co. said it had placed emergency orders for new pumps, but how long it would take for them to arrive was unclear.
It took them 10 days to figure out that earthquake damaged, tsunami flooded, seawater choked pumps wouldn't work? They couldn't yank a pump from a facility that is under maintenance? The pumps from the shut down unit #4 wouldn't work?
Shortly after the batteries died and all power went away, the water temperature reached the boiling point. Pressure exceeded design limits. Three hours after the earthquake the first steam was released. Now the workers risk goes way up because that steam is mostly carried away, but some comes back down on the plant.
The steam internally is used to run a pump that circulates the water inside to cool things off, but at some point all the water is overheated. The heat has no place to go so temperatures continue to rise. Venting steam helps, but more water has to be added. At some point they start running out of clean water to inject.
Batteries from other nuclear plants were sent to the site and mobile generators arrived within 13 hours, but work to connect portable generating equipment to power water pumps was still continuing as of 15:04 on 12 March. Generators would normally be connected through switching equipment in a basement area of the buildings, but this basement area had been flooded. After subsequent efforts to bring water to the plant, plans shifted to a strategy of building a new power line and re-starting the pumps
Plans shifted? Really? Wouldn't you bring in enough people to work as many strategies as you could, only stopping when something else actually worked?
As the reactor heated past 2,200 degrees early last Saturday, hydrogen started building up. This is a well known and documented problem. This happens when the water level drops below the radioactive rods and there is nothing to cool them.
TEPCO knew that they had run out of water and the rods were exposed. Caesium-137 and iodine-131 were detected and that could only happen through uncovered degrading rods. I can't fathom why, but the hydrogen gas was vented into the containment building. It should have been harmlessly routed to a flare stack to burn off, but that may not have been possible without power.
25 hours after the earthquake there was a massive explosion of hydrogen gas. 8 hours earlier there were indications that the rods were uncovered. 5 hours after the explosion the decision was made to start injecting sea water.
There is speculation that the Japanese culture had a lot to do with decision making. The desire to save face, and profits led them to delay far, far too long on the decision to inject sea water. That decision means that a multi-billion dollar investment is toast.
Also the pool that was being used as a seawater source for the pumps ran dry and caused the fuel to be exposed. The pump ran out of fuel again causing the fuel to be exposed.
While all of this is going on nobody thought to check the spent fuel pool in unit #4? There have been reports that the spent fuel pool on unit #2 may have been a problem early on, the spent fuel pool on unit #3 definitely was a problem.
There has been a lot of heroic mention of the "Fukushima 50" fighting to save the plant. At one point it was the "Fukushima Zero" when everyone was pulled out due to high radiation levels. Several analysts have mentioned that due to the danger to tens of thousands of people around the plant that suicide missions shouldn't be ruled out. They should have bought in enough people working in short shifts to keep the required number of people working the many, many problems.
There have been reports that power will be supplied to units 3 and 4 soon. Have you noticed the tons of water they are still pouring into that building? If you stop pouring water the radiation levels soar. If you don't stop you can't fix the electrical. Both units have massive damage from the explosions.
There have been mentions of entombing some portion in concrete. There are serious problems with that approach. If the reactor vessel is entombed the heat has no place to go. It could cause the original concrete containment structure to crack, along with the new.
The spent fuel pool is a bigger problem. You can't put concrete where there is high heat, it crumbles to sand. You can't put much weight on the pool because it is hanging off the side of the reactor structure and the whole thing might collapse. That means you have to put a structure underneath to support it.
These boys have many months of work before they have a handle on this problem.