[en] Chalk River Nuclear Laboratories (CRNL) have undertaken a Waste Disposal Project to co-ordinate the transition from the current practice of interim storage to permanent disposal for low-level radioactive wastes (LLW). The strategy of the project is to classify and segregate waste segments according to their hazardous radioactive lifetimes and to emplace them in disposal facilities engineered to isolate and contain them. To support this strategy, a waste characterization program was set up to estimate the volume and radioisotope inventories of the wastes managed by CRNL. A key element of the program is the demonstration of a non-invasive measurement technique for the isotope-specific characterization of solid LLW. This paper describes the approach taken at CRNL for the non-invasive assay of LLW and the field performance and early operational experience with a waste characterization monitor to be used in a waste processing facility