Why not read a little about what he actually did first before discounting it.
He used Tritium as a moderator.
He didnt build a nuclear bomb and he didnt build a fully functioning nuclear reactor, but he did make a nuclear device that was producing a radioactive output as a result of nuclear reactions/transformations.
Random House (largest English book publisher in the world) still has it listed for sale and continues to list it as a True Story.
http://www.randomhouse.com/book/1673...en-silverstein
If it were not true I would have thought that it would have been uncovered as a fabrication over all these years, the book is chock full of otherwise very easily disputable facts and the names of all parties and occupations involved.