A German concrete pump is being used at Fukushima to spray cooling water on the spent fuel rods. Now that the plant’s own cooling pumps are down and the cooling pools are empty of water, this pump may be all that keeps the spent fuel rods from catching fire and spreading radioactivity over a large territory.

The concrete pump has a flow rate of 160 cubic meters per hour, and that sounds impressive. But does it look impressive? Here’s what the pumping truck looks like compared to a reactor building:

The blue cube is 160 cubic meters. Think of pouring a couple tablespoons of water on a hot frying pan once every hour. Are you cooling the pan down, or just making puffs of steam? Well, at least with a frying pan, the puffs aren’t radioactive.

I suggest a more robust solution, like so:

This pump cascade is built out of shipping containers. Each pump housing contains multiple high-flow pumps, like these. With each pump having a flow rate of 360 cubic meters per hour, and ten pumps per cascade and six cascades in all, total flow rate would be 21,000 cubic meters per hour. This would be enough to completely fill the cooling pools in an hour.

(If you checked out the link, you may have noticed that these pumps have a head pressure of 95 meters. Since the reactor building is only 60 meters, why have a cascade at all? Why not just have a single pump for the entire height? Well, I’m not an expert on hydraulics, but I seem to recall that for a given pump head pressure, there’s a trade-off between flow rate and pumping height. By using the pumps in cascade like this, we reduce the pumping height for each pump and thus the flow rate will be higher. Maybe four pump stages as shown is overkill, but I think at least two stages should be used.)

Each 40-ft container costs about three thousand dollars. Total cost for all 720 containers is approximately $2 million. At ten minutes per container, the entire structure can be built within a week.

By the way, mix boron in the water to prevent a fission reaction, or the water will act as a moderator and there will be a steam explosion. This is discussed at Fairewinds Associates.