On 25th April, the Nuclear Threat Initiative published a paper that says that separated plutonium is a sensitive material that presents both proliferation and nuclear security risks. However, unlike highly enriched uranium (HEU), separated plutonium has not received sufficient attention as a security risk. 8 countries hold more than 375 metric tonnes of separated plutonium, which is produced by reprocessing irradiated nuclear fuel. The paper recommends minimising stocks and specific actions in production, storage, and use of the material, including developing a code of conduct. It says that even small quantities of plutonium could be of interest to terrorists if they see opportunities for acquiring plutonium in a number of locations or for use in a radiological dispersal device (RDD).