In an article in this morning's Albuquerque Journal (sub. req.) yours truly writes about Bob Peurifoy's suggestion that the RRW crew ought to consider uranium as one of the options:

Since scientists detonated the first atomic bomb in the New Mexico desert in 1945, plutonium— a dense, dangerously radioactive metal— has been the nuclear bomb-builders' material of choice.
But it is so expensive, difficult and dangerous to deal with that the United States has been unable for the past 16 years to build a new plutonium bomb.
A veteran of the U.S. nuclear weapons program thinks the weaponeers should consider giving up on plutonium.
In a paper informally circulating among senior government advisers, retired Sandia National Laboratories vice president Bob Peurifoy argues that U.S. nuclear weapons designers should consider using uranium instead.
Peurifoy himself is not completely sold on the uranium idea. The best option, he said, is to stick with the arsenal the United States has.
But if the nation's leaders pursue a plan now being considered to build new nuclear weapons, Peurifoy believes uranium should be one of the options on the table.