Joachim Roenneberg, who foiled Nazi nuclear plan, has died

Loosely related, here's a transcript of the reactions of 10 prominent German nuclear physicists upon hearing the U.S. forces dropped the first atomic bomb: http://germanhistorydocs.ghi-dc.org/pdf/eng/English101.pdf

The scientists, including Heisenberg, Wirtz, and Hahn, had apparently been captured and detained in a bugged house in England, in an attempt to learn more about German nuclear capabilities. It's fascinating to see the varying responses amongst the scientists, from relief that they weren't the ones to actually implement the bomb, to a seeming sense of frustration to having "lost" to the American scientists in figuring out how to do it.

Ray Mears did a fantastic documentary on this subject called the "Real Heroes of Telemark" - https://www.imdb.com/title/tt0499247/ which really shows how hard it was to just survive in that landscape.

Highly recommended viewing (I believe you can find it on youtube).

The German nuclear weapon program had a number of fundamental flaws, according the Wikipedia article on it, and so I assume it would have failed to produce a weapon even if Roennenberg's raid had not taken place. However, at the time no one on the Allied side knew this, and so it made sense to launch the raid.

The operation to blow up the heavy water plant, as well as a lot of Roennberg's other work, is covered in The Allies Strike Back, 1941-1943 by James Holland.

By the end of the war Rønneberg and a small team camped out in a tiny cabin in the mountains hiding from the Germans and planning sabotage missions agains German supply lines. The cabin was rebuilt by Rønneberg in the early 1990s and given to the Hiking association which still maintains it. For a small fee you can spend the night, highly recommended.

Pictures: https://www.ut.no/hytte/3.1381/

Amused that the article calls heavy water "a hydrogen-rich substance". As far as I'm aware it has exactly the same amount of hydrogen as regular water, by definition.

Presumably the author was going for "neutron-rich" but misremembered.

The importance of Heavy Water for the Nazi weapons-development program is overstated. They could simply have used graphite (carbon) as a moderator, as the early Manhattan project breeder reactors did. However, they had made a measurement error on the neutron-absorption cross-section of Carbon, showing it as too high for use as an efficient moderator, hence they went on a wild-goose chase to separate Heavy Water by electrolysis, for use as a moderator using the Norsk Hydro plants at Norway, which were eventually destroyed by Allied sabotage and bombing. All this rigmarole was therefore due to a small laboratory-methods error by some little-known German scientist (probably contamination of his carbon samples with a trace element like Boron or Cadmium). Graphite was readily available in Axis territory - a few more tests would likely have found a purer source without Boron contamination.

The Nazis could never have sustained the industrial efforts required to produce a nuclear weapon. Heavy water is (in comparison) easy to isolate, and can be bought and sold freely in the west today.

[0] http://unitednuclear.com/index.php?main_page=product_info&pr... [1] https://www.isowater.com/purchase/ [2] https://www.sigmaaldrich.com/catalog/product/aldrich/151882?...