Validation status of design methods for predicting source terms

Design methods have been developed internationally for predicting radionuclide source terms for modular HTGRs. These design methods have been used extensively to support reactor design and licensing. Numerous attempts have been made to validate these methods by comparing predictions with experimental data from diverse sources ranging from in-pile irradiation tests to operating HTGRs. In general, the agreement between predictions and measurements is encouraging; however, these design methods are not yet fully validated to the required standards. The current status and additional data needed to complete validation of these design methods are discussed.