RE: Question About Historical Criticality Accident

["Minnema, Douglas" <Douglas.Minnema@ns.doe.gov>]

To add a postscript to this, I understand that it was the same sphere
involved in both accidents, and the second one occurred while demonstrating
the measurement being performed when the first event occurred.

I'm not sure, but I believe that the August 21 date is correct.  It was
always my understanding that the accident occurred shortly after the war was
over. 

However, please don't quote me as authoritative, I am 2400 miles from my
references for the week.  If there is still some question, e-mail me
personally and I will try to find out next week.

Doug Minnema, PhD, CHP
Radiological Control Program Advisor for Defense Programs
DOE
<Douglas.Minnema@ns.doe.gov>

what few thoughts i have are truly my own

> -----Original Message-----
> From:	Willison, James [SMTP:WillisonJ@ttnus.com]
> Sent:	Thursday, September 16, 1999 7:36 PM
> To:	Multiple recipients of list
> Subject:	RE: Question About Historical Criticality Accident
> 
> 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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