Acceleration of Monte Carlo Reactor Cavity Dosimetry Calculations with the Discrete Ordinates Adjoint Function

The discrete ordinates adjoint function is employed to accelerate Monte Carlo reactor cavity dosimetry calculations. Equations for calculating source biasing parameters and weight window l o wer bounds based on importance sampling are developed. The facilities to calculate and use these parameters directly have been incorporated into the MCNP code. Use of the adjoint function is shown to increase the eeciency of the reaction rate calculation by more than a factor of 4 and improve the statistical convergence, with respect to our best manually optimized model. Further, the use of the adjoint function does not require the intuition, guess work, and/or iterative process characteristic of current v ariance reduction techniques.