Radical Reactors Revisited

Although my main interest was in accelerators, one sideline topic accompanying my professional life was nuclear reactors. In my early days, experts kept telling me that governments and industry had backed the wrong horse. They said that the light-water reactor, producing enormous amounts of highly radioactive waste, had been as bad a choice as (remember) the VHS videotape system over Sony's Betamax. In those early days, the Canadian CANDU heavy-water reactor line was considered a better technical solution. One consequence of the "bad choice" is that we now face the problem of safely storing highly radioactive waste. To "incinerate" this waste, my former director-general and Nobel prize-winner Carlo Rubbia even proposed a new type of reactor, the accelerator-driven Rubbiatron.

Given the dramatic climate changes caused by burning fossil fuels, the quest for cheap and safe energy remains unbroken. In an article with the eye-catching, alliterative title "Radical Reactors," published in Nature, Mitchell Waldrop sells old ideas for new. He mentions, among others, Kirk Sorensen, who is promoting the Thorium molten-salt reactor, while an American-Japanese collaboration is working on a fast reactor. Charles Forsberg of MIT said, "Given the erratic output of both wind and solar generators, if you're going to get off fossil fuel, you have to have a serious nuclear program." For such a revival of nuclear energy, global security analyst Edwin Lyman states, "Nuclear is hard, it's expensive, it's slow. Indeed, engineers and scientists must develop better radiation-resistant materials, more efficient heat exchangers, and improved safety systems."

You see Kirk Sorensen (First row, second from the right)
with a banner advertising Thorium as reactor fuel.

This is a sketch of the molten-salt reactor with its famous frozen plug.
In case the cooling of the reactor is lost, the plug melts and opens.
The molten salt will flow out of the reactor vessel
and be caught safely in the container mentioned below.

Let me predict that all these efforts to revive nuclear energy are doomed to failure, for all projects must operate at higher pressures, temperatures, and radiation levels to increase their energy efficiency. 

Materials science still works wonders in developing new materials for specific needs, but we are already approaching limits with the metal and ceramic compounds tailored for the modern nuclear industry. Any increase in pressure, temperature, and radiation level will increase the failure rate of the materials used more than linearly, i.e., the planned new installations are accident-bound. Besides, all those efforts come too late. As a German proverb goes: "The train has left the station."

I prefer soft green to hard nuclear energy, although developments in new energy are slow. Despite enormous funding for electric mobility, the efficient electric car is still wishful thinking. Energy storage is essential due to the erratic output of both wind and solar generators, and this problem still needs to be solved. 

My favored storage medium is hydrogen produced in electrolysis during times when the surge in solar and wind generators in industry and households is low. Hydrogen is quite a "noble" energy, though it can blow up your home if mishandled. Well, there are things you want, and there are those you can do (Das eine was man will und das andere was man kann).

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