The effect of beam interruptions on the integrity of ADSR fuel pin cladding: A thermo-mechanical analysis

► We present beam interruption data for four high power proton accelerators. ► We extend the PTS-ADS code capabilities to include a thermal stress Subroutine. ► We study the thermo-mechanical response in an ADSR cladding to unplanned beam interruptions. ► We perform a thermal fatigue analysis. ► The cladding integrity is severely affected if the current accelerator technology is deployed. During its lifetime in the core, the cladding of an Accelerator Driven Subcritical Reactor (ADSR) fuel pin is expected to experience variable stresses due to frequent interruptions in the accelerator proton beam. This paper investigates the thermal fatigue damage in the cladding due to repetitive and unplanned beam interruptions under certain operational conditions. Beam trip data was obtained for four operating high power proton accelerators, among which the Spallation Neutron Source (SNS) superconducting accelerator was selected for further analysis. 9Cr–1Mo–Nb–V (T91) steel was selected as the cladding material because of its proven compatibility with proposed ADSR design concepts. The neutronic, thermal and stress analyses were performed using the PTS-ADS, a code that has been specifically developed for studying the dynamic response to beam-induced transients in accelerator driven subcritical systems. The lifetime of the fuel cladding in the core was estimated for three levels of allowed pin power and specific operating conditions.