  We consider a system interacting with a chaotic thermodynamic bath. We derive
an explicit and exact Kraus operator sum representation (OSR) for the open
system reduced density. The OSR preserves the Hermiticity, complete positivity
and norm. We show that it is useful as a numerical tool by testing it against
exact results for a qubit interacting with an isolated flawed quantum computer.
We also discuss some interesting qualitative aspects of the OSR.
