The NRC solution is for reactor operators to add hoses or spray systems to permit cooling water to be added to such spent-fuel pools. But because of the location of such pools in older boiling-water reactor designs—specifically, in the upper levels of the reactor building—any water added would ultimately drain down through the building, inundating the emergency pumps in the basement. "Instead of a natural tsunami triggering reactor meltdowns, this 'fix' induces a man-made tsunami inside the reactor building that leads to the same outcome," Lochbaum argues.
Worse, if the spent nuclear fuel did melt down, it too might follow the same path down. "People are worrying that the stuff has maybe melted through the concrete floor" of the spent-fuel pool, noted John Monninger, an NRC risk analysis official in Japan, on March 20, 2011, according to the transcripts. "The next stop is the top of the torus," or the doughnut-shaped ring containing the extra cooling water. Brian McDermott, then-director of the NRC's Division of Preparedness and Response, completed the thought on a conference call, according to the NRC transcripts: "Then you've got potential steam explosions with this melting into the water in the torus. And then after that, who knows where it goes."
The real solution, according to Lochbaum and other experts, is to require spent fuel to be moved from pools to more permanent storage in massive concrete and steel casks after five years of cooling down. That would reduce the amount of fuel in the pools, reduce the overall heat, permit more water in the pools themselves in case of emergency as well as reduce the amount of radioactive material that could be released if an accident occurs. "Thinning out the spent-fuel pools is a no-brainer," Lochbaum says.
As NRC staff noted during the Fukushima emergency, when there was concern that the spent-fuel pool at Unit 4 may have lost its cooling water as well as been damaged by the reactor building explosion, adding cold water to already hot fuel can create a problem in its own right. "That's going to 'rubble-ize' [sic] those fuel pools," argued the NRC's Casto on March 17, 2011, who had witnessed a similar accident in Hungary, according to the transcripts. "You put that water on that hot fuel and rubble-ize it, you're going to get particulates also. So you're going to have some level of significant release… plus it's being carried away in the steam."
Regardless, the 23 boiling-water reactors in the U.S. that are the same as those at Fukushima Daiichi continue to generate electricity today. In Japan, just one month before the devastating magnitude 9.0 earthquake and tsunami, the complex's stricken Unit 1 reactor had received approval to operate for another decade. And on March 10, 2011, the NRC licensed the boiling-water reactor of similar design and vintage at Vermont Yankee to operate for another 20 years (pdf), just one day before the Fukushima crisis.
The one thing that the NRC crisis guide for boiling-water reactors "doesn't really do is tell you how to stop [a meltdown]," Casto noted on March 16, 2011, according to the transcripts. The guidelines do not reveal "how to mitigate it, other than keeping water on it." Despite a tsunami-triggered calamity at the Fukushima Daiichi nuclear power plant, water remains the key to nuclear safety.