Characterization of end-of-life rod internal pressure in PWR fuel

The end-of-life (EOL) fuel rod internal pressure (RIP) is a critical parameter for assessing the performance of spent fuel during dry storage and transportation. At issue are several potential degradation mechanisms that are strongly dependent on rod internal pressure. Experimental EOL RIP data of pressurized water reactor (PWR) spent fuel rods were compiled from available non-proprietary sources and used to develop a model that quantifies the fuel rod's gas content in terms of its molar mass, from which the rod internal pressure can be derived using the ideal gas law. Application of the model is illustrated using temperature profiles measured in a spent fuel storage system. The results show that for rod-average burnup of ∼60 GWd/MTU and peak cladding temperature as high as 400 °C, cladding stresses are less than 100 MPa for the clear majority of spent PWR fuel.