Neutronic Calculations for Shielding the Tokamak Fusion Test Reactor Diagnostic Penetrations

The arrangement of the tokamak fusion test reactor diagnostic system results in a number of streaming paths that are directly visible to the plasma. Two important configurations of these penetrations have been examined: (a) the large isolated ducts through the primary igloo shield at the plasma midplane, and (b) the coplaner diagnostic tubes through the substructure beneath the plasma. The spatial distribution of the flux and spectrum has been determined as preliminary input for the design of the diagnostic shield boxes.