Energy From Thorium Discussion Forum

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PostPosted: May 07, 2015 1:24 pm 

Joined: Mar 14, 2014 5:26 pm
Posts: 4
I realize there would be difficult-to-meet conditions if the target of a fission bomb, fusion bomb, neutron bomb, etc is to be neutralized. But are these conditions stringent enough to be show-stoppers?

At first glance, I would consider xenon-135 (and, to a lesser extent, cadmium-113m) extremely useful due to its very high cross sections for scattering (4 * 10^5 barns) and absorption (2 * 10 ^6 barns) in the thermal spectrum - provided you know the device operates primarily in the thermal spectrum. In this case I imagine it would at least be conceptually possible to contaminate the intended fuel with xenon to the point that the device would take much longer to deliver its full energy load. Lower impact intensity, then, would result in a lower risk of cancer in the periphery of the affected region. You probably wouldn't be able to completely negate the effect in this case, but at least you could moderate its effect slightly.

In this case, suddenly a fission reactor would be very useful for its ability to partially shield a city from an atomic weapon, as there are basically no other sources of these isotopes. A good way to show the public the difference between fission for electricity and fission as a weapon.

That said, I expect a nuclear weapon would work primarily in the fast spectrum. Is there a similar course of action one could employ to mitigate such a weapon, presumably with some conditions? Or am I grossly oversimplifying this? (I have posted only a few times, but have been a lurker for a couple years)

PostPosted: May 07, 2015 3:00 pm 
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Joined: Nov 30, 2006 3:30 pm
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Location: Alabama
They tend to neutralize themselves over time as the tritium gas inside the weapon used to "boost" the yield decays to helium-3, a neutron absorber.

PostPosted: May 07, 2015 4:26 pm 

Joined: Nov 14, 2013 7:47 pm
Posts: 574
Location: Iowa, USA
Xenon-135 would not be an effective means to denature nuclear fuel. Xenon-135 has a half life measured in hours, any fissile material that has been considered for use in a nuclear weapon have half lives measured in thousands, millions, or billions of years. All one would have to do to get rid of the xenon is wait a day, or perhaps a week, for it to decay away. If one is impatient then the xenon, which is a gas, can be brought out by crushing or melting the core and allowing the gas to escape.

How one would render a nuclear weapon core unusable would depend on the intent. If the intent is to prevent theft of nuclear material there are a number of means. One primary means is that fresh from the reactor fuel has enough high gamma emitters as fission products that it cannot be approached safely for years after it has been removed, it must be stored under water. After it's allowed to "cool" for years it is still quite a radiation source that it will show on detectors currently placed along traffic bottlenecks inside our borders. Ten feet of water for shielding is easy for a stationary storage pool, nearly impossible for a container that must move down a road or rail.

As Mr. Sorensen points out current multi-stage weapons rely on tritium for their high yield. With a half life of about 12 years the tritium must be replaced every four years or so or the yield will not be within specification. It will still go *BOOM*, but only with a fraction of it's original energy.

What seems to be popular to denature nuclear fuel are isotopes of the primary element that have relatively short half lives, but not too short that it can be reasonably waited out. Plutonium-238 is one, it cannot be chemically removed from the more valuable fissile isotopes, and with a half life around 90 years it cannot be waited out. The plutonium-238 also produces enough heat and radiation that it can destroy most explosives that could be used as a detonator.

I will end with my disclaimer, I'm not a nuclear engineer. While I endeavor to teach myself and others about nuclear technology I have had no formal training in the field, I just read a lot.

Disclaimer: I am an engineer but not a nuclear engineer, mechanical engineer, chemical engineer, or industrial engineer. My education included electrical, computer, and software engineering.

PostPosted: May 07, 2015 9:17 pm 

Joined: Jun 19, 2013 11:49 am
Posts: 1552
You can build a thermonuclear weapon of effectively unlimited yield without tritium boosting of primaries.
It just requires more plutonium/HEU and is thus heavier and more expensive.

3g of tritium and 2g of deuterium is cheaper than the required amount of fissiles to make the difference.

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