CPV code 90521420 designates Transportation of intermediate level nuclear waste in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
90521420 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 90521400 (Transport of radioactive waste).