What is plutonium register?

As an AI language model, I do not have access to current information about a plutonium register. However, if you are referring to the Plutonium Registry, it is a database established by the United States Department of Energy to track the uses and locations of plutonium materials. This is important for ensuring the safety and security of these materials, which can be used to build nuclear weapons. The registry is used to monitor the production, use, storage, and disposition of plutonium within the United States and other countries that receive plutonium from the U.S. through various agreements.