RE: Question About Historical Criticality Accident

["Willison, James" <WillisonJ@ttnus.com>]

A report of the two criticality accidents at Los Alamos is found in the
book, "The Medical Basis for Radiation Accident Preparedness",
Proceedings of the REAC/TS International Conference, October 18-20, 1979
Oak Ridge, Tennessee, Editors Karl F. Hubner (sorry I dont know how to
do Umlauts), MD and Shirley A. Fry, MB, ChB.  The paper is titled "What
Happened to the Survivors of the Early Los Alamos Nuclear Accidents?",
by Louis H. Hempelmann, Clanrence C. Lushbaugh, and George L. Voelz.
The paper refers to two accidents.  The first, on August 21, 1945, at
9:55 pm involved a physicist stacking tungsten carbide bricks around a
nickel-plated plutonium sphere.  The physicist dropped one of the bricks
when he noticed that the neutron flux was increasing rapidly.  This is
NOT the event protrayed in the movie.

The accident depicted in the movie matches the description and pictures
of the event that occured on May 21, 1946.  While it involved a
nickel-plated plutonium sphere, it was surrounded by concentric
hemispherical shells of beryllium that the physicist was keeping apart
with a screwdriver.  When the screwdriver slipped out the top shell fell
and the assembly went critical.  The top shell was immediately grabbed
off the assembly.  

I also have an old AEC publication titled Living with Radiation, the
Problems of the Nuclear Age for the Layman, published in 1959.  It has a
figure showing a criticality event labeled as May 1946.  The drawing is
crude, but it is clearly the same assembly described above for the May
21, 1946 event.  It also shows the individuals in the room and the
approximate doses.  This diagram is remarkably similar to the movie
protrayal of the criticality event at Los Alamos.  The only problem, of
course is that it occured approximately one year later than in the film.


Jim Willison, CHP, PE
willisonj@ttnus.com


>One of the better known radiation accidents and early criticality
fatality was
>an  experiment that happened at Los Alamos in August 1945.  It has been
depicted
>(with great historical inaccuracies) in such movies as "Fat Man and
Little Boy".
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