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INVESTIGATION ON A GENERALIZATION OF THE WILKINS THERMALIZATION THEORY VALID FOR HOMOGENEOUS MEDIA TO HETEROGENEOUS AND QUASI-HOMOGENEOUS MEDIA (in German)

Journal Article · · Nukleonik (West Germany) Discontinued with vol. 12
OSTI ID:4829923
For the model of a monatomic heavy gas, a relatively simple second-order differential equation for the case of an infinite expanding homogeneous medium was derived by J. E. Wilkins, Jr. from the integial equation desciibing the thermalization of neutrons by the development of the reciprocal nuclear mass. A study was made to translate the Wilkins considerations to a finite expanding heterogeneous medium. For the mean spatial flux spectrum in the individual medium fractions, an integral equation system was formulated which was then converted by utilization of the heavy gas model into a corresponding system of differential equations. The coupling of the equation system was effected by the collision probabilities P/sub ij/. The equation system is discussed for some special cases. Approximations to the mean temperature and scattering nuclear mass were obtained by passage to the limit to (quasi-) homogeneous media. By application of the method to a two-zone cell, the formal theory was reduced to the Wilkins equation for an infinite homogeneous medium undei- the assumption that the scattering collision on uranium causes no energy modification of the neutrons. Surprisingly simple relations are obtained when the Wilkins spectra of the individual medium fractions are superposed approximately. In this case the differential equations are reduced to simple algebraic expressions for the spectral mean in the individual volume fractions. (tr -auth)
Research Organization:
Siemens-Schuckertwerke A.G., Erlangen, Ger.
NSA Number:
NSA-16-019739
OSTI ID:
4829923
Journal Information:
Nukleonik (West Germany) Discontinued with vol. 12, Journal Name: Nukleonik (West Germany) Discontinued with vol. 12 Vol. Vol: 4; ISSN NUKKA
Country of Publication:
Country unknown/Code not available
Language:
German

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