6.64. A number of measures can be used to reduce the likelihood and mitigate the consequences of human intrusion into radioactive waste disposal facilities. These measures include active institutional controls and/or a system of durable physical barriers. Furthermore, compartmentalization of the waste may reduce the consequences of an intrusion event. Probably the most substantial reduction of estimated doses may be achieved by emplacing the waste at greater depth. In certain situations, an alternative site may also be considered, in particular if the risk of human intrusion is greater owing to the presence of water or mineral resources at a site that may be exploited at some time in the future. Such measures should be seen as part of the optimization of protection. Although such measures are unlikely to completely eliminate doses from human intrusion, they may reduce the likelihood of human intrusion and/or its consequences.