: a radioactive metallic element that is chemically similar to uranium and is obtained in nuclear reactors especially as a by-product in the production of plutonium — see Chemical Elements Table
Examples of neptunium in a Sentence
Recent Examples on the WebThe amount of neptunium found in the air monitor at the school was a thousand times below the regulatory action level, said Mr. Edwards of the DOE.
Kris Maher, WSJ, 28 Apr. 2021 Sometime in 2017, the radioactive element neptunium 237 was also detected near the school.
The Cincinnati Enquirer, Cincinnati.com, 26 July 2019
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'neptunium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.