Evaluation Formula for Radiation Duct Streaming

Abstract

Author's works on an evaluation formula for the radiation duct streaming are reviewed.

The formula, which describes the direct and albedo components, is derived in a generic straight duct geometry. It is expressed by the product of spatial distributions which are represented by twice and eight-time reflected components, and power of an albedo matrix. The computational method of the spatial distributions is outlined.

The application of the formula to bent ducts is then described. The inflow of radiations to downstream at a corner of multibent ducts is formulated with the flux in the upstream leg. Using the obtained inflow current as the source term to the downstream, the formula predicts the radiation flux in the downstream leg.

The estimation of the leakage component is made by a simple point kernel method. When the streaming effect of radiations of the leakage component is important, the formula is combined with the point kernel method.

The formula is then extended to more general duct geometries, where a straight duct penetrating two material zones and a bent duct with general crossing angle are taken up. The estimation method of the flux in these ducts is briefly outlined.

The formula has been tested through the application to a variety of streaming problems, and showed to be highly applicable.

KEYWORDS:

• radiation streaming
• spatial distribution
• duct streaming
• neutron streaming
• gamma-ray streaming
• leakage
• streaming formula
• semiempirical formula
• albedo
• point kernel method
• bent duct
• slit
• cylindrical duct
• radiation shielding