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 reactor line using heavy water was considered a better technical solution. One consequence of the "bad choice" is that we are now faced with the problem of the safe storage of 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 climatic changes due to the burning of fossil fuels, the quest for cheap and safe energy is unbroken. In an article with the eye-catching alliterated title Radical Reactors published in Nature, Mitchell Waldrop sells old ideas for new. He mentions, among others, Kirk Sorensen 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 below-mentioned container.

Let me predict that all these efforts for a comeback of nuclear energy are doomed to failure, for all projects must work with higher pressures, temperatures, and radiation levels to increase their energy efficiency. 

Material science still works wonders in developing new materials for specific needs, but we already approach 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 states: The train has left the station.

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

My favored storage medium is hydrogen produced in electrolysis during times when the surge on solar and wind generators in industry and households is low. Hydrogen is quite a "noble" energy, although it may blow up your home when poorly handled. 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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