BOISE, Idaho (AP) — Idaho State University says it can't find a small amount of radioactive, weapons-grade plutonium about the size of a U.S. quarter, and federal officials are proposing an $8,500 fine.

The U.S. Nuclear Regulatory Commission said in a statement Friday that the university can't account for about a 30th of an ounce (1 gram) of the material that's used in nuclear reactors and to make nuclear bombs.

Officials say the amount is too small to make a nuclear bomb but could be used to make a dirty bomb to spread radiation.

The university says documents from 2003 and 2004 identify the material as being on campus. But the school in Pocatello says a search in October failed to find the plutonium.

School officials didn't immediately respond to inquiries from The Associated Press.

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