V.S.O.P. is a computer code system for the comprehensive numerical simulation of the
physics of thermal reactors. The application of the code implies processing of cross sections,
the set-up of the reactor and of the fuel element, neutron spectrum evaluation, neutron
diffusion calculation, fuel burnup, fuel shuffling, reactor control, and thermal hydraulics of
steady states and transients. The neutronics calculations can be performed in up to three
dimensions. Thermal hydraulics is restricted to gas-cooled reactors in two spatial dimensions.
Evaluation of fuel cycle costs over the reactor life time is made using the present worth
method. A broad description of the features of the code has been published in Ref. /1/
