An improved capability for modeling the transient behavior of the uniq
ue Advanced Neutron Source Reactor (ANSR) accumulator design has been
developed. The ANSR accumulator behavior may now be simulated using an
external model that is coupled to a RELAP5/MOD3 ANSR facility system
model via a parallel virtual machine (PVM) connection. Existing RELAP5
code models were found to provide marginal results for simulating beh
avior of the unique ANSR accumulator design, and an improved accumulat
or modeling capability was desired. A new model for representing the A
NSR accumulators, assessment and demonstration of that model, and the
general methods by which external models may be coupled with RELAP5 sy
stem models using PVM connections are described.