Community and Historical Society Discuss Sixth Episode of WGN’s Manhattan

Richard Feynman chats with Robert Oppenheimer and a couple of other scientists back in the day at Los Alamos. CourtesyLAHS

LAHS News:

As WGN’s Manhattan series continues, there was another great audience on Sunday for the Los Alamos Historical Society’s viewing of the sixth episode.

The Los Alamos Historical Society would like to send out a special thanks to this audience who contributed a lot of the information in this press release, thank you! The Society has collected some of the questions and discussion points heard on Sunday. Our bulletin board in the Museum is updated, and these points as well as those from previous episodes are available at and on our Facebook page. 

Join the Los Alamos Historical Society for a viewing and discussion of Manhattan, 8-9:30 p.m., Sundays at Time Out Pizzeria in Los Alamos

What was the X-10 reactor?

The X-10 reactor was an original part of the Manhattan Project in Oak Ridge, Tenn. It went critical Nov. 4, 1943. The reactor acted as a pilot reactor, creating the first significant amount of plutonium for the project. Officials were able to see that creating the plutonium worked and built the site in Hanford, Wash. to produce the plutonium needed for the Atomic bombs.

Did Los Alamos scientists go to Oak Ridge?

One reported story is of Richard Feynman going to Oak Ridge, Tenn. in order to inspect the safety of the uranium enrichment program. The workers at Oak Ridge did not know a lot about uranium and the dangers it posed. Feynman wrote up a report on the safety problems that existed at Oak Ridge and how to solve them.  Despite the need for secrecy, Feynman ultimately ended up explaining to workers at what point Uranium would go critical and how to use cadmium to absorb neutrons and stop a chain reaction.  The Oak Ridge directors agreed to redesign the factory with this information in mind. 

After the directors redesigned the factory, Feynman went back to look at the plans.  Not knowing how to read blueprints or what all the symbols meant, he felt very lost, but did not want to let on that he did not understand what he was being shown. He took a chance and pointed to a symbol, and asked a question about what he hoped was a valve but was sure they’d say it was a window. Turned out it was a valve, and one with a problem, and they all thought he was a genius for catching it!

Was the German bomb program ahead?

The Germans did not develop a program on the scale of the Manhattan Project: it would have been more difficult, as their cities were being bombed, and they felt less pressure because they were confident in their scientific advantage over the Allies. They were not ahead, and the Allies had little military intelligence on the German program until after V-E Day, when the Alsos Mission discovered they never succeeded in even making a critical nuclear pile.

Did anyone swallow plutonium?

Aug. 1, 1944, chemist Don Mastick was holding a glass vial of 10 mg of plutonium, which snapped. He took an estimated 10 micrograms into his mouth and swallowed around 1 microgram. Like Fritz, he could stand six feet away from a radiation monitor and set it off with his breath, and like Fritz he was given the contents from his stomach pump to separate out the plutonium. This wasn’t the first or the last accident with plutonium during the Project: Twenty six men who inhaled or ingested small amounts of plutonium have been followed medically. They have not shown a greater cancer risk than the general population.

Was there a doctor behind the fence?

The radiologist in the Tech Area, Louis Hempelmann, was young, receiving his MD only five years before joining the Project, but was asked to join because of his experience working at a leading radiology center and at the Berkeley Rad Lab. He was so alarmed by Mastick’s accident that he asked Oppenheimer for permission to undertake experiments to better understand the effect of plutonium on the body. This led to a human experimentation program in which 18 people were injected with plutonium, the subject of Eileen Welsome’s book The Plutonium Files.


  • Marie Curie did die from anemia and was nearly blind, and her notebooks are still dangerously radioactive.
  • Uranium nitrate solution was called “green water,” and it is more dangerous because the neutrons are slowed. Helen Prins’ realization in the episode is nearly identical to that of Emilio Segrè when he visited Oak Ridge.
  • The DOE Primer on Tritium Safe Handling Practices suggests consumption of a diuretic, such as beer, to reduce the biological half-life of ingested tritium.
  • This is the Army was produced in 1943 and did feature Ronald Reagan. There were two theaters in Los Alamos, with backless benches for seating.
  • DDT was used extensively in the 1940’s as a pesticide and there are many accounts of children running in the spray behind DDT trucks. DDT was also marketed to housewives as a way to kill insects in the home. We have been unable to find any information on how much DDT was used in Los Alamos during the Manhattan Project and whether they sprayed children directly to kill head lice.