Wiktionary
a. (context of a radioactive or other substance English) of a purity suitable for the manufacture of weapons
WordNet
adj. of a quality adequate for use in weapons (especially in weapons of mass destruction); "weapons-grade plutonium"; "weapons-grade anthrax"
extremely strong or concentrated or durable; "industrial-strength detergent"; "weapons-grade salsa" [syn: industrial-strength]
Wikipedia
A weapons-grade substance is one that is pure enough to be used to make a nuclear weapon or has properties that make it particularly suitable for nuclear weapons use. Plutonium and uranium in grades normally used in nuclear weapons are the most common examples. (These nuclear materials have other categorizations based on their purity.)
Only fissile isotopes of certain elements have the potential for use in nuclear weapons. For such use, the concentration of fissile isotopes uranium-235 and plutonium-239 in the element used must be sufficiently high. Uranium from natural sources is enriched by isotope separation, and plutonium is produced in a suitable nuclear reactor.
Experiments have been conducted with uranium-233. Neptunium-237 and some isotopes of americium might be usable, but it is not clear that this has ever been implemented.
Substances for chemical and biological warfare may also be described as weapons-grade.
Usage examples of "weapons-grade".
Six months ago they had been so confident of victory, the gaseous diffusion plant was online and within two years enough weapons-grade uranium would be separated to make the first bomb .
For the past twenty-four hours, the Japanese plutonium ship Yuduki Maru, with two tons of weapons-grade plutonium aboard, has been off course.
In his home PC he had all sorts of files on North Korea and suspicions that they were attempting to manufacture weapons-grade plutonium in a nuclear reactor.
The North agreed to dismantle its breeder nuclear reactors in favor of light-water reactors, less capable of producing weapons-grade nuclear material.