Re: Thermalisation optimisation

["Dr. Hector Rene Vega Carrillo" <rvega@cantera.reduaz.mx>]

>I am looking for information to help optimise the thermal neutron flux in
>the cavity around a 370GBq Am/Be and 370GBq Pu/Be source.
>What thickness of polyethelene will produce optimised thermal neutron flux
>in this configuration?
>I'm considering polyethelene moderator surrounded by a Be reflector, then a
>1m thick concrete bunker. (if practical)
> 
>  Anthony Barber                                         
>  Queensland University of Technology 
>  a.barber@qut.edu.au  
>  61 7 3864 3566
>  fax: 61 7 3864 3993

Anthony,

Some time one of my students did an experiment with a 239PuBe
neutron source.  We use a cylindrical tank  filled with a
moderator with the neutron source in the center and we measure 
the radial distribution of the thermal neutrons.  We use two
moderator media, water and polyethylene in pellets (density
was 0.92 g/cm^3).
Tank radius = 30 cm
Maximum of thermal neutron flux with water = 3 cm
Maximum of thermal neutron flux with polyethylene = 4 cm
Radial distribution of thermal neutron of this polyenergetic
neutron source was checked with Monte Carlo Method.

Also you can use Monte Carlo methods to simulate your calculation.

Hector




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Hector Rene Vega Carrillo
Centro Regional de Estudios Nucleares
de la Universidad Autonoma de Zacatecas
C. Cipres 10, Fracc. La Penuela
98068 Zacatecas, Zac. 
Mexico

Phone/FAX: (492) 2 70 43
e-mail: rvega@cantera.reduaz.mx
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