Justin has over 25 years' experience in developing and maintaining computer based models to predict the transfer of radionuclides through the environment following accidental and routine releases. He is the lead developer of PC-CREAM 08, which is an application for performing radiological impact assessments of routine following continuous discharges of radionuclides to the environment. He has contributed to a number of IAEA modelling and radiological impact assessment programmes including EMRAS, MODARIA II and MEREIA, and has provided support to IAEA training courses. He also provides secretariat support to the UK's Atmospheric Dispersion Modelling Liaison Committee (ADMLC | Atmospheric Dispersion Modelling Liaison Committee).