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PostPosted: Jul 26, 2009 11:59 pm 
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India has launched its first nuclear-powered submarine, becoming only the sixth country in the world to do so. It was built entirely in India with Russian assistance and a second one is due to be constructed shortly. Until now, only the US, Russia, France, Britain and China had the capability to build nuclear submarines.

This brings India closer to becoming the first nation in decades to develop a nuclear triad, and the first nation to do so in the Indian Ocean area. While this development does not shift any balance of power in the region, it certainly gives both Pakistan and China something to think about. There is something else though: it will also give India a case for becoming a permanent member of the UN Security Council, a discussion the current permanent five members are probably not looking forward to with any relish.

Anyone that thinks terms can be dictated to this country, on any matter, had better re-evaluate their position.


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PostPosted: Jul 27, 2009 12:59 pm 
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Tonu wrote:
Following from NTI Global Security Newswire
http://www.globalsecuritynewswire.org/g ... 3_1673.php
Far as I could understand, USA did like taking back all spent fuel, which India did not agree to. Instead, India proposed to retain right to reprocess all spent fuel including any received from USA. Also, far as I can understand India might not be interested in passing this fuel to anyone else anyway - however, they might be more keen to reprocess same after first pass use, and then utilise the byproduct bred fuels and/or remaining Uranium for use in either another power reactor, or for experiemnts or for weapons making - all for their own use.
Or am I wrong ?

Spent fuel of TAPS I&II is already under IAEA control. Also the LWR spent fuel cannot be used for weapons. It gives at best reactor grade Plutonium, which can be used for fast reactors or thorium fuel for reactors. The weapon program is run from indigenous uranium in a separate set of facilities, so far called research facilities.
Fast reactor development proves that adequate reprocessing skills are available in India. Launch of nuclear sub proves the same for PWR. The imports are for commercial reasons like sufficient industrial capacity not being available or mining not producing enough uranium to meet the requirements.
The premise of the quote appears to be only partially correct.
Some facilities are not designated civilian as the research being conducted shall be hindered by IAEA inspections. PFBR is a case in point.


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PostPosted: Jul 29, 2009 11:12 pm 
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Thanks for the update DV82XL

Quote:
Anyone that thinks terms can be dictated to this country, on any matter, had better re-evaluate their position.
Well, the world is unable to dictate anything even to North Korea! Why expect they might succeed with India?

Thanks jagdish for the details.
A question - why cannot Plutonium from a LWR be used for weapons? Can it not be centrifuged enough to make weapons grade ? Just wondered.


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PostPosted: Jul 30, 2009 12:47 am 
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The isotope Pu240 has an annoying habit of setting of the bomb too early.
In a commercial reactor the fuel is left in the reactor so long that some of the Pu239 gets fissioned (a lot of it actually).
If some gets fissioned then some also does a capture to become Pu240.
Fuel that has been in the reactor for 2-3 years has too much Pu240 relative to Pu239 to make a decent bomb (or you have to be REALLY good and if they are that good then we aren't going to be stopping them anyway).
You want to use U238 that has only been in the reactor for 3 months or so to generate weapons grade.


(Speculation warning) I think you could use a normal reactor and remove the fuel after just three months but everyone would see what you are doing and it would be tough to buy more uranium fuel on the legal market afterword.


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PostPosted: Jul 30, 2009 12:42 pm 
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Lars wrote:
The isotope Pu240 has an annoying habit of setting of the bomb too early.
In a commercial reactor the fuel is left in the reactor so long that some of the Pu239 gets fissioned (a lot of it actually).
If some gets fissioned then some also does a capture to become Pu240.
Fuel that has been in the reactor for 2-3 years has too much Pu240 relative to Pu239 to make a decent bomb (or you have to be REALLY good and if they are that good then we aren't going to be stopping them anyway).


Thanks for that - very interesting.

Is the Pu240 issue only relevant in LWR or does the same thing also happen with heavy water?
Also, what happens with the Pu240? Does it itself fission (and generate heat/power as well as trigger the explosion), or does it just eject extra neutrons/protons unpredictably in order to set off the device, while converting itself back to Pu239 or some other element?


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PostPosted: Jul 30, 2009 2:47 pm 
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The phrase we use regarding Pu is: "the evil of the evens." Even numbered isotopes of Pu are problematic for the bomb designers. Some are very problematic. Just look at a glowing marble of Pu-238....


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PostPosted: Jul 30, 2009 10:27 pm 
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Carey Sublette's Nuclear Weapons FAQ identifies Pu240 as "the major contaminant of concern in plutonium for weapons use".

The spontaneous fission rate of 415k/sec-kg, leading to 1M neutrons/sec-kg, may just be the cause of this concern, 4.5 orders of magnitude higher than Pu239. 1% contamination of Pu240 in Pu239 rules out gun-type device designs, while above 7% guarantees preinitiation and reduced yields, even with highly sophisticated implosion systems. The much higher spontaneous neutron background vastly reduces the insertion time allowed to take the device supercritical and initiate it before a spontaneous neutron in the wrong place buggers things up.

Two factors militate against pushing Pu production beyond 7% Pu240 for device use - mass-based seperation is 3x harder than for Unat, reducing the per-stage seperation capacity by a factor of 9, and the tails still contain large amounts of expensive Pu239 - a case of chucking the baby out with the bathwater.

Apparently Fat Man could have used a gun-type system (0.9% Pu240 contamination), but for whatever reason (maybe to gain experience to assist later designs with more badly-contaminated Pu), implosion was used.

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PostPosted: Jul 30, 2009 11:12 pm 
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fnord wrote:
Apparently Fat Man could have used a gun-type system (0.9% Pu240 contamination), but for whatever reason (maybe to gain experience to assist later designs with more badly-contaminated Pu), implosion was used.


"Thin Man" nuclear bomb was the proposed plutonium gun-type nuclear bomb which was developing during the Manhattan Project. Its development was aborted when it was discovered that the spontaneous fission rate of nuclear reactor-bred plutonium was too high for use in a gun-type design. The design was an early nuclear weapon idea proposed before plutonium had been successfully bred and it was assumed that a critical mass of plutonium, like uranium-235, would be able to be assembled in this simple way. However when the speed that the moving mass would have to obtain to avoid pre-fissioning was calculated, it was found to be impractically high and the project was abandoned.

Implosion is the only viable mechanism for a PU fueled device, and because of the complexity of this method it is usually not the first type of weapon a new nuclear state produces.


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PostPosted: Aug 05, 2009 3:44 pm 
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Interesting! But, is the Pu240 problem only relevant in LWR or does the same thing happen with heavy water too?


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PostPosted: Aug 05, 2009 8:49 pm 
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I think that applies to Pu irradiation under any spectrum, just to differing amounts - I think the %age of fissions goes up with incident neutron energy, but I'm not certain.

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PostPosted: Aug 06, 2009 4:15 am 
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Tonu wrote:
Interesting! But, is the Pu240 problem only relevant in LWR or does the same thing happen with heavy water too?

Pu 240 is produced in PHWR too. It is just that much fewer people use the heavy water reactors. Therefore Plutonium for weapons is produced in separately earmarked reactors and fuel irradiated for a short duration.
The plutonium recovered from spent nuclear fuel for LWR or HWRs, is very useful for fast reactors or with thorium fuel and therein lies its value. Anti-proliferationists however object violently. It therefore gives a good cover to obstructionists. No one has ever been able to stop proliferation by real bad guys at a state level. Islamic extremists in Pakistan shall be the first terrorists (Non-state actors) to get it by present indications.


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PostPosted: Aug 06, 2009 4:39 am 
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Tonu wrote:
Interesting! But, is the Pu240 problem only relevant in LWR or does the same thing happen with heavy water too?



PHWRs burn most of the plutonium they make. About 0.9 percent Pu is contained in spent LWR, in a PHWR that is reduced to 0.2 percent.


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