Experimental validation of the LILW storage strategy applied in the national Dutch interim storage facility

Collection, treatment and storage of all radioactive waste e.g. LILW, HLW, depleted uranium, NORM and TENORM is in the Netherlands performed by COVRA (Central Organization for Radioactive Waste). Like many other waste management organizations, COVRA developed and adopted different waste storage strategies for the different types of waste to be managed. During 2004 - 2008 a novel a non-destructive assay method INDSS-R (Indoor Survey System - Radiation) has been developed to validate the applied waste storage strategies and procedures at COVRA. This paper deals with the development of the novel non-destructive assay method, especially dose rate and thermal neutron flux measurements, and the impact on the storage strategy of LILW, the minimization of the radiation exposure for employees during routine inspections of storage building, the public and the environment. The INDSS-R gives a good insight into the spatial dose rate, gamma photon flux and neutron flux distribution. The method proved to be a good alternative for the weekly manual radiological control routine. Replacing the weekly control by a yearly scan with the INDSS-R method, a dose reduction of 0.5 mS/y per LILW storage module has been achieved