Graphite and Heavy Water aren’t necessary to cause natural uranium to go critical. Quite the contrary. They are neutron absorbers that are used to prevent a runway reaction.

The Chicago pile achieved the first sustained chain reaction when the graphite control rods were withdrawn, and the reaction was stopped when they were reinserted.

#27 I think you may be confusing natural uranium with U-238. Natural uranium has U-235 in it (about 0.6 percent), which is fissile. If enough of it is brought together a chain reaction will ensue by virtue of the presence of the U-235. Pure U-238, what is left over after enrichment, will not produce a chain reaction, no no matter how large the pile.

You may have heard about the radioactive nature of “depleted uranium” used in alloyed tank armor and armor-piercing anti-tank rounds. This is because while depleted-uranium is mostly U-238, it still contains a small amount of U-235 and other fissile uranium isotopes.

#27 Your execrable views on Israel aside, you should think long and hard about the implications for the safety of United States of Iran getting nuclear weapons. The Iranians have made chanting “death to America” part of the Friday worship services at the University of Tehran. They’ve been doing it for 30 years. I think you should entertain the possibility that they mean it.

And that is all you need to know folks. billrowe is either:
- an Iranian agent provocateur
- an anti-Semitic kook
- another western culture loathing Lefty

Wherever he falls on the irrational US/Israel hating spectrum he cannot be reasoned with so responding to him is pointless.

BTW, there’s no such thing as a 100 level nuclear engineering course. The introductory nuclear course is 200 level.

http://www.matthiaskuentzel.de/contents/ahmadinejads-demons

But, so what? Yes, Iran has accumulated the technological know how to do practically anything commercial or weapons related in the nuclear field—with the requisite inclination, dedicated resources and time. AS far as I am concerned we all need an Iranian limited nuclear weapon capability to deter the apartheid Israel and its patsy the US from continuuing their illegal imperialistic, immoral policies in the mideast. I am not worried about Iran using their bomb except as a defensive deterrent. But a strong Iran will be able to strongly support those anti-Israel anti-US immoral policies in the mid-east. This is what really worries Israel and the patsy US.

Iran needs to continue its technological advancement and give the “west” the polite diplomatic middle-finger salute.

Iran would be stupif to transfer their low enriched stockpile out of the country on the “promise” to receive 20% enriched uranium fuel back for its Tehran research reactor. I can guarantee the west will hold the delivery hostage to some new illegal demands. At best Iran should agree only to transfer the uranium in stages as the enriched fuel is received; and only enough low enriched fuel to make the new fuel. The “west” openly states its goal is to have Iran forego its enrichment— so only an idiot would trust them.

First, Iran is playing its diplomatic stalling game with masterful finesse. They have been at the table for years with the Europeans, and now with us. Feeble sanctions are enacted, and then flouted by various nations. And in the background, the steady hum of thousands of gas centrifuges, both in Qom and Natanz, creating the stuff of Iran’s dream: the Jew-liquidating Final Solution: the Mullah Of All Bombs.

Second, Russia and China are not displeased with Iran’s challenge to the West, and will not impede it in any way. But, to avoid burning all bridges to the West, Russia and China will continue to play tag-team in threatening to veto any UN Security Council action, swapping the good-cop/bad-cop roles from time to time. They know that the present US administration will not consider military pressure on Iran without a UN mandate. Russia and China are Iran’s insurance policy against any possible UN action. With their backing, Iran fears no sanctions, and has zero incentive to negotiate in good faith.

As our president receives worldwide acclaim (or at least Norway-wide) for his policy of appeasing Iran’s “legitimate concerns” in endless “good-faith” negotiations, one cannot avoid comparison with the last comparable exercise in appeasement of dictators, some seventy years ago.

There is every reason to believe that the same mistakes are being made today by our president. Unwillingness to face unpleasant facts is a matter of pride with him.

Appeasement didn’t work for Chamberlain and it won’t work now.

[Flashback: Bullwinkle: “Watch me pull a rabbit out of my hat!” Rocky: “That trick never works.” Bullwinkle: “This time for sure.” Bullwinkle (after trick fails): “I gotta get a new hat.”]

Thanks for the excellent primer. A couple of minor quibbles:

1. The Russian built reactor at Bushehr is set to be switched on by the end of the year. It will still take some months to create enough plutonium for one bomb. The real question is who will take possession of the spent fuel rods? The chances of Iran getting their hands on those rods is pretty slim since the IAEA will no doubt want to keep an eagle eye on them.

2. I am not worried about the uranium stash at Natanz. The IAEA has been allowed to inspect that amount constantly and have a high level of confidence that it couldn’t be spirited away to complete its enrichment to bomb grade levels – unless Iran kicked the inspectors out and then all bets are off. The point being, the Iranians can afford to appear generous with their LEU at Natanz because it was never going to be used to make a bomb in the first place.

3. How close are they to either the HEU or plutonium bomb? Got to still be a year at least given the technical hurdles that would have to be overcome with an implosion device. It is a serious challenge to any program to be able to focus the explosives with such a high tolerance of timing and accuracy. Some of the parts are extremely hard to get such as those sophisticated detonators that we intercepted going to Iraq a few years before Saddam was ousted. Not saying it can’t eventually be done but I think our intel guys were right when they said Iranians would have the capability between 2011 and 2015.

It isn’t just them. I’d have to do some digging but I recall a poll of the general population and a vast majority of the population also feels they have a right to pursue nuclear technology. I believe it is a mistake of the West to think that Iranian dislike for the mullas necessarily translates to being any less nationalistic than the next country.