Work during phase II of the project was aimed at following up and assessing retrofitting measures taken on the basis of recommendations derived from the safety analysis carried out by the GRS/BGR. The long-term safety considerations of the safety analysis were updated and deepened by follow-up activities. For this purpose, the transport events of radionuclides at the Morsleben repository during the post-operational phase were calculated by means of a close-to-reality mine model, the code MARNIE developed by the GRS to handle a complex mine model of the Bartensleben mine. Work and the model assumptions of the mine workings topology and of the hydrogeology of the site were based on the knowledge available to the GRS when carrying out the safe...