CONUP: A code that calculates tag gas concentrations for reactor components

The CONUP code calculates the current tag isotopic concentrations for the Tag Gas Analysis Code, SMTAG. The combined codes, CONUP and SMTAG, represent the Tag Gas System. CONUP produces tag concentrations that are decayed and transmuted over specific reactor core cycles. The calculated concentrations are used, together with measured concentrations, as input for the SMTAG code, which identifies the failed reactor components that have released tag gas. The CONUP code has two modes for calculating isotopic concentrations: absolute and incremental. In the absolute mode, the CONUP code calculates concentrations from the beginning of the reactor startup through the current cycle. In the incremental mode, the CONUP code processes concentrations from the last reactor component cycle for each component. The incremental mode saves significant processing time because the concentrations are updated only for the current cycle. A description of the underlying physical model and method of solution are presented. A description of the code and a user`s guide are also given, along with example input and corresponding concentration output.