Transient Analysis in the Ascó Nuclear Power Plant Using RELAP5/MOD2

The thermal-hydraulic analysis group at Asociación Nuclear Ascó has prepared a model of the plant using RELAP5/MOD2. Protection and control sys-tems have been added as well as a kinetic model in order to accurately analyze plant transients. A new system to record process information collected by plant instrumentation is being installed and will provide a more accurate follow-up of operational and incidental transients of the plant. The current recording system provides adequate information in terms of safety and operation, but there are some interpretation problems when it is used to validate a thermal-hydraulic model. Under these conditions, the selection of transients to assess has been the most important step on qualifying the model. Once a steady-state calculation is achieved, six actual transients are selected to validate the model. From this analysis, it is concluded that the level of qualification of the model is sufficient to validate the predictions of the behavior of the plant under such situations. This process will continue for other transients to broaden the capabilities of the model.