Guest Post by Willis Eschenbach

For many people the sticking point for nuclear power is, what do we do with the waste? We can “vitrify” the waste, but what do we do with it after that?

Figure 1. The process of “vitrification”. Liquid nuclear waste (solid fuel rods dissolved in acid) is converted into a solid glass like substance. Image Source

Unfortunately, the people in almost every country of the world have not been able to make up their minds what to do with the solidified nuclear waste. As a result, in almost every country it’s just sitting around. And nuclear material sitting around is dangerous. So here’s my brilliant plan. Nuclear lawn darts.

We have a pretty good idea what was happening on the bottom of the ocean millions of years ago. This is because there are places in the ocean where what you might think of as the local underwater climate never changes. It’s always cold. It’s always dark. There’s not much current. There is a continuous rain of very fine particles from the upper ocean. And it’s been like that for the last X million years.

We know that this has been the case for millions of years because we can take a core sample of the top layers of the thousands of feet of silt up at the top, and we can see that it has been undisturbed for that time. The conditions have not changed much year after year for millions of years. Every year a tiny amount is added to the thickness of the primordial ooze at the ocean floor.

Those spots in the mud at the ocean bottom seem to me to be ideally suited for the storage of nuclear waste. We know these areas are geologically stable on the multi-million year scale. It also gives us multiple layers of protection both from human interference, as well as from accidental release.

It is isolated from humans for the most obvious of reasons—it is way down at the bottom of the ocean.

It isolates any leak through the use of several redundant mechanisms. First the nuclear waste is already solidified. So in order for it to escape it would have to leach out of the solid glass. At that point it finds itself inside a sealed welded stainless steel container. However even the best of steels may develop some chemical corrosion. At that point it is encased in concrete. Suppose it gets through the concrete. Then it is still contained by the stainless steel outer container. Again, perhaps the outer container cracks. At that point the leaking radioactivity finds itself buried under 50 feet of silt and mud. And if somehow it manages to make it to the environment, it comes out in the best spot, the spot where radioactivity will do the least damage. That spot is the bottom of the ocean. Here’s why.

On land there are a number of scarce elements that are necessary for life. One of them is calcium. We needed for our bones and our teeth. So the bodies of land animals have developed special mechanisms that gather up these various scarce elements like calcium and concentrate them so we can use them in our bodies.

This makes for trouble. When radioactive elements enter the environment, our bodies avidly seek them out. We concentrate these radioactive elements, and they then damage our bodies.

The ocean, on the other hand, is a veritable stew of all kinds of chemical compounds. Take iodine as an example. Radioactive iodine on land is concentrated by our bodies and stored in our thyroid glands. And since there is so little iodine around on land, any radioactive iodine in the environment stands a good chance of being picked up by some living animal. Thus, it is dangerous.

In the ocean, however, iodine is quite common. It’s responsible for the “medicinal” smell of seaweed. There’s lots and lots of iodine in the ocean.

So where will a spill of radioactive iodine cause more damage? Obviously, the answer is on land. In the ocean, at the very bottom of the ocean, that radioactive iodine will be immediately diluted among millions and millions of atoms of iodine which are already there. This has two effects. First, the sea creatures use iodine as well—but they have no special mechanisms to pick it up and concentrate it because it exists all around them. Second, because of the large amount of natural iodine in the ocean, the concentration of radioactive iodine in the ocean is very low compared to natural abundance. So between the animals not concentrating the iodine, and the low and well-diluted levels of radioactive iodine within the reservoir of natural iodine, any release is much less dangerous in the ocean than on land. And for the obvious reasons of dilution and separation from the larger surface biosphere, a release is much less dangerous at the bottom of the ocean than at the top.

Now, how to get the nuclear waste down to the ocean bottom and bury it there? I propose a very low-tech method, using nuclear lawn darts. The plan is to seal two or three of the canisters of vitrified nuclear waste into what is in essence a giant stainless steel tuna fish. This tuna would be loaded aboard a large vessel. At a predetermined spot in the ocean it would be dropped over the side. If sophisticated steering is desired, that can be achieved through the use of steerable vanes. With proper hydrodynamic design, they should be capable of reaching reasonable speeds. This should be enough to bury them entirely in the mud at depth. (Naturally, a suitable site with appropriately soft silt, will need to be chosen.)

Figure 2 shows a cross-section drawing of what such a disposal system might look like. It is modeled after the shape of an oceanic tuna, which are capable of speeds up to 45 miles an hour (70 km/h). This should give it plenty of speed to be able to bury itself deeply in the ocean floor.

Figure 2. Cross section of a Nuclear Lawn Dart. The illustration shows the outer stainless steel shell, the inner concrete, and the stainless steel casks containing vitrified nuclear waste. Three individual containers are shown inside the dart. Background Graphic.

This design gives great strength and durability, and provides redundant levels of containment for the nuclear waste.

Figure 3. The process of dropping a nuclear dart.

Each nuclear dart will have a buoy to mark the location, attached to a short length of cable which will deploy automatically when the nuclear tuna strikes the ocean bottom. Each buoy will contain a transponder that can report back the condition (temperature, pressure) of the dart. These will allow that particular nuclear tuna to be located, identified, and retrieved as necessary. This would allow all nuclear darts to be retrieved quite simply by hooking onto the cable. That cable is connected to a lifting ring at the stern of the nuclear dart and which would serve to hoist directly up out of its resting place. If there were to be any radioactive leakage, it could be detected and the leaking and nuclear dart could be retrieved and fixed. Anyhow, that’s my bozo solution for how to deal with nuclear waste. Put it into a streamlined projectile, drop it over the side of a ship, and let it bury itself in the bottom of the ocean. What could be simpler?

Possible objections? One I can think of is the issue of heat. Radioactive decay gives off heat. How well this will be dispersed by the surrounding mud is an interesting question. However it doesn’t seem to be an unsolvable question. Simple experimentation will bring that to a quick resolution. That will give us the limitations on the number and amount and density of these kind of disposal units that the ocean floor can sustain. In addition, since each dart will be (relatively) cheap, we can reduce the concentration of the fuel in each dart and increase the number of darts. This will reduce the heat generated in each dart.

Another is the deceleration when the dart hits the ocean floor. Again, this can be measured (it will differ for each site) and the darts suitably engineered to resist the forces involved.

So. What are the possible objections to this scheme? All submissions gratefully accepted.

My best to all,

w.

[UPDATE] A number of people have said in comments that if I can retrieve them, someone else can too … a valid point. Scratch the retrieval cable, bury them and forget about them.

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