  The Spallation Neutron Source (SNS) is an accelerator-based neutron source
being built in Oak Ridge, Tennessee, by the U.S. Department of Energy. The SNS
will provide the most intense pulsed neutron beams in the world for scientific
research and industrial development. The facility is scheduled for completion
in 2006. The project is a collaboration between Lawrence Berkeley National Lab,
Argonne National Lab, Los Alamos National Lab, Oak Ridge National Lab,
Brookhaven National Lab, and Jefferson Lab. The Run Permit System (RPS) is a
software based system which has several key functions critical for safe
operation of the machine. It coordinates machine mode and beam parameter
changes with the timing system, verifies the Machine Protection System (MPS)
hardware configuration, and provides an interface for masking MPS hardware
inputs when necessary. This paper will describe the primary functionality of
the Run Permit System and the interface between the Run Permit System, the
Machine Protection System, and the timing system.
