Hanford Site in Washington State... It is a secure location that is
Guessing you're not a Washington resident, or else you'd know that this "environmental remediation" is only progressing at all due to the WA state Department of Ecology suing the federal government over it. And that its current rate, it will be hundreds of years before the waste *we know about* has been cleaned up. Time during which shit continues to leak, and spread.
Generally speaking, the whole place is considered an absolute disaster by Washingtonians.
This sample was not weapons ready. If it were, it would have been used in a weapon and not left behind.
You obviously didn't read TFA. 99.96% purity. The article can only guess at why it didn't make it into a bomb. From the article:
"But the puzzling thing is, why didn't this plutonium make it into the bomb?" In 1944, the Americans were working flat out to develop a nuclear capability - it's strange that any first large batch of plutonium-239 should be stored and not used, he says.'
They go on to postulate that it was because the safe it was being stored in became contaminated, so the whole shebang got tossed.