Article

2005-02-10 Syria-Lebanon-Iran

Russia to sign nuclear fuel deal with Iran

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Posted by Steve White 2005-02-10 2:13:18 PM|| || Front Page|| [12 views since 2007-05-07] Top

#1 Maybe someone more knowledgable about power reactors can answer this. What's to stop Iran from replacing the outer ring of Russian produced fuel rods with locally produced un-enriched uranium, irradiating those rods, and then extracting plutonium from them?

Posted by ed 2005-02-10 2:52:47 PM|| 2005-02-10 2:52:47 PM|| Front Page Top

#2 Ahm... LOL.. that was the funnied question today! Bhwahahahahaha... ROFL

I don't want to get too technical, let's explain briefly... no, let's just summarize it: It won't work. All you'd get is un-enriched uranium irradiated rods.

Posted by Sobiesky 2005-02-10 2:59:55 PM|| 2005-02-10 2:59:55 PM|| Front Page Top

#3 Sobiesky,

Care to expand on your answer? I am no NucE. My limited understanding is that U-238 neutron capture results in Pu-239, which is highly fissile. Additional neutron capture results in less fissile isotopes. So for best performance, isotope separation is desired, but not neccessary for a crude bomb.

A quick google:
Plutonium is a by-product of the fission process in nuclear reactors, due to neutron capture by uranium-238 in particular. When operating, a typical nuclear reactor contains within its uranium fuel load about 325 kilograms of plutonium, with plutonium-239 being the most common isotope. Pu-239 is fissile, yielding much the same energy as the fission of a U-235 atom, and complementing it.

Well over half of the plutonium created in the reactor core is "burned" in situ and is responsible for about one third of the total heat output. Of the rest, one sixth through neutron capture becomes Pu-240 (and Pu-241), the balance emerges as Pu-239 in the spent fuel.

An ordinary large nuclear power reactor (1000 MWe LWR) gives rise to about 25 tonnes of spent fuel a year, containing up to 290 kilograms of plutonium. Plutonium, like uranium, is an immense energy source. The plutonium extracted from used reactor fuel can be used as a direct substitute for U-235 in the usual fuel, the Pu-239 being the main fissile part but Pu-241 also contributing.

Posted by ed 2005-02-10 3:13:14 PM|| 2005-02-10 3:13:14 PM|| Front Page Top

#4 i think the issue is that those rods aint pure enough, you still got to concentrate the stuff.

Posted by Liberalhawk 2005-02-10 3:31:08 PM|| 2005-02-10 3:31:08 PM|| Front Page Top

#5 A sticking point in your scenario might be: The un-enriched rods would not produce as much power. The other rods would make up the difference, thus depleting faster requiring more frequent re-fueling. That surely would be detected even by the IAEA. Also, the in-core shift in power distribution to the U-235 enriched rods may produce undesired boiling, then melting then... Somebody call Jane Fonda.

Posted by Zpaz 2005-02-10 3:33:05 PM|| 2005-02-10 3:33:05 PM|| Front Page Top

#6 It's not a matter of concentration. Plutonium separation is just a matter of chemical separation, a fairly simple process. Weapons grade plutionium is made by irraditing U-238 for a few months (short time = mostly Pu-239, less other Pu isotopes). The US and other declared nuke powers use dedicated reactors for this. But what's to stop a regime like Iran from serrupticiously using a commercial reactor to do the same thing?

Posted by ed 2005-02-10 3:39:15 PM|| 2005-02-10 3:39:15 PM|| Front Page Top

#7 Thanks Zpaz. But the reactor might be run at less than designed power and musical fuel rods can be played when the U-238->Pu239 rods are exchanged every few months. So what kind of monitoring will there be? Will there be an outside monitor watching the reactor ops?

Posted by ed 2005-02-10 3:49:45 PM|| 2005-02-10 3:49:45 PM|| Front Page Top

#8 Ed,

Your explanation in #3 is accurate. There is nothing to stop a state from Iran from diverting plutonium.

Zpaz's description of what occurs inside the reactor is incorrect.

Also, so what if someone's monitoring it? Does anyone think the UN has the balls to do anything about it?

(And I am a nuclear engineer)

Posted by Dreadnought 2005-02-10 3:55:08 PM|| 2005-02-10 3:55:08 PM|| Front Page Top

#9 Your welcome Ed. I had the same thought. Run at a lower power. That sounds feasible. Hopefully a spy on the ground can point out they are not running at full power or you can detect it from the amount of rejected heat. All power processes reject about 2/3 of the heat produced in the reactor. Where you reject to is typically a river, lake or atmosphere via cooling towers. You would be able to estimate power levels from the reject heat plumes. Some conventional plants use waste heat to heat buildings at which point it would be harder to detect.

Also, re-fueling is a major operation that is detectable from satellite because with the reactor shutdown your waste heat plumes go away. Everyone will be watching for those indications. More frequent shutdowns should raise eyebrows, but knowing the bureaucrats, they might write shutdowns off to poor maintenance forcing the shutdowns.

Posted by Zpaz 2005-02-10 4:03:47 PM|| 2005-02-10 4:03:47 PM|| Front Page Top

#10 Thanks Dreadnought. I am hoping monitoring may cause the Iranians to fear a US attack, not that I think the US would attack an operating reactor, but attack the regime itself.

Posted by ed 2005-02-10 4:04:28 PM|| 2005-02-10 4:04:28 PM|| Front Page Top

#11 How so Dreadnought? The overall reactivity in your core is less with the U-238 heavy rods installed. That means more frequent refueling regardless of how you might try to shift power distribution in the core.

Posted by Zpaz 2005-02-10 4:12:50 PM|| 2005-02-10 4:12:50 PM|| Front Page Top

#12 Ed, you are confusing FBR (fast breeder-unmoderated) reactor type with the standard type of reactor. FBR design allows for surrounding the core with U-238 tubes that get bombarded with neutrons and part gets converted to Pu-239. You need high grade fuel for this type of generation of fissile material (usually 20% of PU-239 and highly enriched uranium oxide--don't remember from the top of my head what the degree of enhancement is necessary). You need also a good metallic coolant, mercury, lead or NaK. Water won't work, will simply boil off in no time.

In the case of standard reactor, what would happen is that the outer ring of the U-238 rods would function as inhibitor on the reaction of the next ring, which would again influnce the next ring--an uneven distribution of fission process, with the temperature gradient towards central segment. As Zpaz points out, this may produce undesired effects like structural problems, namely bent rods that may lock the system. If caught in time, this may not result in meltdown. So, in the end you may get a miniscule amount of Pu-239 in the outer ring U-238 rods, but your reactor may be going into a scrap.

Posted by Sobiesky 2005-02-10 4:21:35 PM|| 2005-02-10 4:21:35 PM|| Front Page Top

#13 [Off-topic or abusive comments deleted]

Posted by Shaiter Thrutle8631 TROLL 2005-02-10 4:45:59 PM|| 2005-02-10 4:45:59 PM|| Front Page Top

#14 Off-topic or abusive comments deleted]

Posted by Shaiter Thrutle8631 2005-02-10 4:45:59 PM|| 2005-02-10 4:45:59 PM|| Front Page Top

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