A method is presented for solving neutron transport problems in slab geometry with the application of discrete ordinates numerical integration to the Boltzmann transport equation.Neutron spectra for water, iron and carbon layers are calculated and compared with experimental data. Good agreement is obtained between computed and measured values for both angular distributions and the energy spectra of neutrons. The calculated neutron spectra in an iron-water layer are also presented as an example of solutions derivable for neutron transport problems in multi-layered shield.

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A procedure for the direct numerical integration of the transport equation in slab geometry is introduced, The angular flux is expressed as a series of Legendre polynomials. The iteration process is utilized for the spatial integration of the transport equation. Prior to applying this method both to neutrons and to photons, a series of studies on the photon penetration problem has been performed to assess its validity. The first code, the EOS-1, was prepared for the NEAC 2206 computer to perform the above mentioned work and also to solve some practical problems of not very large scale. A comparison of energy buildup factors obtained by the EOS-1 code with those from the moments method and from the Monte Carlo method indicates that the method presented in this paper provides a correct treatment of the attenuation of radiations in a slab. The results also agree well with the energy spectra from the moments method, with the energy spectrum measured in the Bulk Shielding Reactor and with the energy-angular flux distributions obtained with 6°C o and 137Cs sources behind iron and aluminum plates, both with respect to spectrum pattern and to absolute values.

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Albedo data were calculated by ANISN for iron-covered concrete slab as well as for iron and concrete single layer slabs. Neutron is allowed t o be incident on a slab with each of 14 energy groups ranging from 10 MeV to 1 keV and reflected with energy between and including the incident group and the lowest group. Neutron direction is described with 8 discrete angles for incidence and reflection respectively. Discussion w a s made f o r t h e dependency on slab thickness and on angle and energy of incidence and reflection. A s a result, albedo data calculated by ANISN showed good agreement with the other similar data and consequently they were concluded t o be sufficiently valid for use in shield design calculation.