Radioactive waste is classified as high level (HLW), intermediate level (ILW) and low level (LLW): High level waste is highly radioactive liquid waste that is produced when spent nuclear fuel is reprocessed. It is self-heating and requires cooling. Over 95% of the radioactive material arising from the nuclear power industry is high level, but it has a very small volume. At Sellafield (British Nuclear Fuels Limited, Cumbria), liquid high level waste is solidified into a glasslike form (borosilicate) which reduces its volume even more. Intermediate level waste is sufficiently radioactive to require shielding during its handling and transportation. It is currently stored at nuclear sites. Low level waste consists of lightly contaminated materials and is disposed of by burial at approved sites, principally at the surface repository at Drigg in Cumbria.