Earthquake response spectra for seismic design of nuclear power plants in the UK

► Seismic design of UK nuclear power plants usually based on PML response spectra. ► We review derivation of PML spectra in terms of earthquake data used and procedure. ► The data include errors and represent a small fraction of what is now available. ► Seismic design loads in current practice are derived as mean uniform hazard spectra. ► The need to capture epistemic uncertainty makes use of single equation indefensible.