#ebr-ii

[man-and-atom]

Here is a more extensive look at fuel reprocessing and refabrication in EBR-II.

Some of the footage is actually the same as that in the IFR film we recently showed, although that is less obvious because this is in black-and-white. Close comparison with another EBR-II film shows that the material used for coating the glass moulds for casting the fuel pins was at some point changed from graphite to thorium oxide, or perhaps vice versa.

The narration emphasizes an important economic aspect related to the closed nuclear fuel cycle. The longer it takes for fuel removed from the reactor to be cooled, reprocessed, made into new fuel, and reloaded into the reactor, the larger the total inventory of fuel required per megawatt of capacity. Locating the reactor and the fuel facility together shortens this time, and incidentally avoids the inconvenience of shipping the spent and fresh fuel. Reprocessing methods which do not require waiting months for decay of the short-lived fission products can further shorten the time, although this means that all operations have to be carried on behind heavy shielding.

Early on at EBR-II, the fuel remained in the core 135 days, was cooled for 15 days, and could be reprocessed in under 30 days. Thus the out-of-reactor fuel inventory could be reduced in principle to 1/5 of the quantity in the reactor. This is a big difference from concepts involving oxide fuel and away-from-reactor PUREX reprocessing, in which the out-of-reactor inventory is often half or more of that in the reactor. Later on, the metal fuel pin performance was improved to the point that fuel could remain in the core close to two years. Although a somewhat larger cooling time would have to be allowed, this still implies a very small out-of-reactor inventory. So, even if the quantity of fuel required in the core per megawatt of output is greater than with oxide fuel, the overall requirement might actually be less.

Given that, in general, a metal-fuel fast-neutron reactor has a larger breeding gain (the plutonium which it produces per megawatt-day of operation, over and above that required for feeding back into the reactor) than an oxide-fuel fast reactor, the overall concept appears very favorable for supplying fissile material in a fully-nuclearized energy economy.

[man-and-atom]

Is nuclear energy sustainable?

The way it is practiced today, no. Although its environmental impacts are small compared to other energy supply options, the constant need for uranium-235 means that newly-mined uranium must be supplied at a relatively modest price. World production capacity and mineral resources simply will not suffice to substitute for more than a modest part of the energy now supplied by fossil fuels. Hence the extension of fission energy in its present form is not a feasible path for a world energy transition.

Is this a problem?

Consider : the very first generation of power was from Experimental Breeder Reactor Number One. The large-scale development of industrial nuclear energy only began once it had been shown that a regenerative fuel cycle was possible. In such a cycle, plutonium and ²³³U take the place of ²³⁵U in supporting the chain reaction, and the whole energy of natural uranium and thorium can be used.

As a result, not only is the energy value of uranium already mined increased a hundredfold, but the quantity of fuel required to supply the total needs of civilization is so small that it can reasonably be supported from high cost sources such as seawater.

The scientists, engineers, and technologists who developed fission energy as we know it today recognized that it was, in essence, an intermediate step. From the very beginning, they devoted considerable effort to the ultimate goal of sustainable energy. The “Integral Fast Reactor” represents one of the most promising results of this effort. It shows that the nuclear path is one we can take with confidence.

[man-and-atom]

Here is a fascinating glimpse of the development effort towards solving a difficult industrial problem.

In order to properly address world needs for energy, nuclear power must be based on reactors operating in a “breeder” or super-regenerative cycle. One practical implication is that fuel must be recycled repeatedly. Accordingly there is a need to reduce, so far as possible, the costs of the operations involved in taking discharged fuel elements, freeing them from impurities which affect the operation of the reactor, adjusting the composition, and manufacturing new elements.

Practically speaking, this involves performing a variety of chemical and mechanical operations on objects and substances which are so violently radioactive that they must be carefully isolated and shielded from any living beings ― including plant staff. As shown, part of the approach is to test prototype equipment using much less hazardous working materials, so that closer scrutiny can be imposed, and adjustments can be made. Once everything works properly in these “cold” tests, then the equipment can be installed in the “hot cell”, where it will rapidly become so contaminated that any kind of modification, maintenance, or repair would be a large-scale operation.

[man-and-atom]

The quality of this video transfer, apparently an episode of a program called Challenge produced for National Educational Television, is quite poor. But where else will you get a chance to see, not only the charge face of a sodium-cooled fast breeder reactor, but also a reprocessing plant in operation?

EBR-II incorporated a number of innovative features, but the on-site facility for recycling and refabricating discharged fuel is certainly the most distinctive. Designs based on the EBR-II experience, under the name Integral Fast Reactor, are considered to be some of the most favourable for introducing the fully-closed nuclear fuel cycle. In a world which so badly needs low-emissions energy sources which can be counted on for many generations to come, it seems incredible that this option has essentially been left to lie for half a century.

[man-and-atom]

One of a group of six brochures from Argonne National Laboratory describing experimental facilities located at the National Reactor Testing Station (also known as Idaho National Engineering Laboratory, and by other names) near Arco, Idaho. We can tell that these brochures are from the early 1990s, because of the emphasis on the Integral Fast Reactor program. IFR was an advanced design of fast-neutron breeder reactor which promised better economics and a shorter “doubling time” (the amount of time required for a breeder to produce the fuel charge necessary to start up another breeder of the same type) than designs such as the French Superphenix.

You can see the whole group here.

Sad to say, one reason some people doubt warnings about climate change is that Al Gore proudly stood up in the United States Senate to announce that the Clinton Administration was terminating the IFR program. It can be hard to accept that decarbonization is necessary, when that message is coming from such a visible opponent of the most effective means of decarbonization!

On a largely unrelated note, I’ve gone back and tagged a number of posts with “my scans” so that they are easier to find.