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PostPosted: Feb 21, 2007 11:09 am 
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http://www.osti.gov/bridge/servlets/pur ... 183237.PDF

And the best of it all : Th230 (Ionium) is extremely poisonous. This means that handling of the MSR fuel - consisting of Th232 and spiked with Th230 - will have to be shunned as the pest. As will any relevant quantity of U233.

Next question : How much Ionium is needed for spiking and what's the cost of extracting it out of depleted or natural uranium ?


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PostPosted: Feb 21, 2007 11:15 am 
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Excellent find, Elling! Since ionium is one of the basic radiological hazards of a uranium tailings pile, I can certainly envision a "lemonade-from-lemons" approach here with ionium extraction and a market for spiked thorium.


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PostPosted: Feb 21, 2007 11:24 am 
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PRODUCTION OF IONIUM FROM A PITCHBLENDE RESIDUE

by C. W. Kuhlman, W. S. Knecht, R. D. Piper
Mallinckrodt Chemical Works
St. Louis, Missouri

Date of Issue: July 28, 1955

ABSTRACT


At the request of the Atomic Energy Commission, Mallinckrodt Chemical Works designed and operated a plant for the recovery and purification of thorium-230 (ionium) from a pitchblende residue available at the St. Louis Production Center. This plant was based on the Peppard process consisting of a concentration of the thorium by an extraction with 100% tributyl phosphate followed by a hydrofluoric acid strip. The fluoride product is then purified by a solvent extraction flow sheet in hot laboratory equipment.

An account of the technology utilized and an outline of the chemistry on which it was based is given in this report.


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PostPosted: Feb 21, 2007 11:28 am 
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I. Introduction

In December of 1954 it was requested of Mallinckrodt Chemical Works by the Atomic Energy Commission that a plant be designed and built for the recovery of thorium-230 (commonly referred to as ionium) from pitchblende residues. Production of multi-gram quantities of this material was desired in February of 1955. Accordingly, a plant was designed and installed using the basic process developed by D. F. Peppard and his associates at Argonne National Laboratory.

Ionium is an alpha emitter with a half life of 83,000 years. Since it is a daughter product of uranium-238, it is found in uranium ores at secular equilibrium in a concentration of 18.4 parts per million parts of uranium. Since thorium is considered to be a bone seeker in the body, the alpha-active isotope, ionium, is an extremely hazardous radioactive poison resembling plutonium and radium. Also associated with uranium in secular equilibrium with its decay products are protactinium-231 (32,000 year alpha-emitter) and radium-226 (1560 year alpha) present in concentrations of 0.33 and 0.35 parts per million parts of uranium respectively. The biology of protactinium is almost entirely unknown, but in absence of contrary information it must also be assumed to be a bone-seeker, e.g., the most hazardous possibility. In addition to these long lived alpha emitters, a large variety of short lived alpha, beta, and gamma emitting isotopes are found with uranium. The most important of these are thorium-234 (24.5 day beta), lead-210 (22 year beta), polonium-210 (140 day alpha), actinium-227 (21 year beta), thorium-227 (18.9 day alpha), and radium-223 (11.2 day alpha). The hazards introduced by these radioactive decay products seriously complicate the extraction of ionium from a uranium ore.

Two alternative ionium sources were considered. A waste liquor resulting from the ether extraction of a nitric acid solution of Belgian Congo pitchblende concentrate was available. This liquor, called "raffinate liquor" in this report, consisted essentially of a nitrate solution of all of the nitric acid soluble constituents of pitchblende with the exception of the uranium, radium, and lead isotopes. Prior to 1951 this "raffinate liquor" was found by Peppard to contain approximately 7 mg/liter ionium. In addition to the "raffinate liquor", a "raffinate cake" was available. This cake had been produced by the precipitation of the alkali insoluble metals in the "raffinate liquor" with lime and filtration of the cake. This "raffinate cake" containing all of the important components of the raffinate liquor had been stockpiled over a period of 10 years.

The stored "raffinate cake" was selected as a starting material for the ionium process because: 1) the material had aged long enough to permit the beta and gamma emitters to decay to negligible activities, and 2) analysis of currently produced "raffinate liquor" indicated an ionium level about one tenth of that expected from earlier work. Whether this lower ionium concentration was due to a pitchblende starting material not being in secular equilibrium or to some other cause was not unequivocally determined. At any rate, the absence of beta and gamma radiation greatly simplifies the problem of shielding personnel during the production operation. An analysis of a particular sample of "raffinate cake" is shown in Table I. The composition of this material is extremely variable hence this analysis should be considered indicative of the type of material used only, and in no sense as representative of the gross composition of the "raffinate cake" storage' pile.

The ionium content of the "raffinate cake" was found to vary widely. Individual samples taken from even closely adjacent locations at the storage pile varied over a four fold range. However, analysis of composite samples at M allinckrodt and at New Brunswick indicated that a considerable section of the storage pile had an approximate overall ionium content of 5 g Io per dry ton of cake with individual spot samples within this area varying from 2.5 to l4 g/ton. This concentration was considered sufficient for processing. Considerable soil had been mixed with this raffinate pile during pile. moving operations during the past 5-9 years adding to the heterogeneity of the starting, material. During the two month operation of the plant an overall ionium content of 10 g/ton was actually realized. The problem of obtaining precise analytical data of the gross composition
of the pile is an extremely difficult one and has not yet been satisfactorily solved.

The extremely short time for the engineering and construction of a production plant imposed; several special restrictions on the design and operation of the process.
  1. The process flow sheet developed by Peppard had to be adopted in toto without.preliminary piloting despite the comparatively very small scale on which his work had been carried out.
  2. An existing building had to be utilized to house the process equipment.
  3. Equipment-had to be selected which was immediately available from the manufacturer or was in surplus at a Commission site.
  4. A considerably greater health risk was accepted than would be tolerated over any more extended period of time.
  5. Very little time could be devoted to making any recalcitrant process step or piece of equipment work during the plant startup period if an alternative was available even though the alternative might present less promising ultimate possibilities.
It is important to recognize these conditions when reading the description of the process since a more deliberate effort would undoubtedly utilize very different technology for some parts of the flow sheet.

The materiall in this report is based on the experience of the Mallinckrodt plant, and development work in the laboratory at Mallinckrodt. In addition, a great deal of information has been abstracted from Peppardes work. It has been impractical to clearly distinguish in all cases between work done at Nallinckrodt laboratory and that done at Argonne because of the great overlap. Essentially no claim to originality is made for any part of the flow sheet. In many cases data of the two sites are combined into a single table or graph.


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PostPosted: Feb 21, 2007 8:48 pm 
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Elling wrote:
Th230 (Ionium) is extremely poisonous. This means that handling of the MSR fuel - consisting of Th232 and spiked with Th230 - will have to be shunned as the pest. As will any relevant quantity of U233.

Next question : How much Ionium is needed for spiking and what's the cost of extracting it out of depleted or natural uranium ?

I don't understand what's the big deal about Th230 spiking.
Spiking is meant to seriously impede diversion to weapons or terrorist use.
No amount of Th230 will do such a thing, even pure Th230.
Th232 is already useless for weapons.

Like Pu239, Th230 is an alpha emitter.
But with a half-life over three times longer, it is over three times less radioactive than Pu239.
In solid form, Pu239 can be handled quite safely, as alpha rays are non-penetrating.
A chunk of Pu239 feels warm to the touch, due to the decay heating.
A chunk of Th230 would be similar, only much cooler.
Another example is the Am241 in domestic smoke detectors.
Locked in the solid metal source inside the detector, it is quite harmless, despite being 175 times more radioactive than Th230.

So Th230 would certainly not create a hazard that would in any way impede diversion to terrorists.
It would however add immeasurably to the hazard of a radioactive dispersion device (RDD, a.k.a. "dirty bomb"), if the solid can be turned into a fine powder.

.


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PostPosted: Feb 21, 2007 10:50 pm 
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jaro wrote:
I don't understand what's the big deal about Th230 spiking.

Ionium spiking makes the rate of U-232 generation in the fuel go through the roof, and it works in the thermal spectrum. U-232 ruins the weapons potential of the U-233.


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PostPosted: Feb 22, 2007 7:16 am 
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Kirk Sorensen wrote:
Ionium spiking makes the rate of U-232 generation in the fuel go through the roof

OK, now I get it -- thanks Kirk.

But is it worth two neutrons per Th230 to get a bit of U232 ? (can an MSR spare that much ?)

Also, it sounds like it would be a pretty slow production rate, with significant amounts appearing only after years of operation.
By contrast, the denaturing is most important in fresh fuel, which is not contaminated by loads of fission products & transuranics.

It doesn't seem like a very effective strategy.

.


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PostPosted: Feb 22, 2007 9:25 am 
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jaro wrote:
But is it worth two neutrons per Th230 to get a bit of U232 ? (can an MSR spare that much ?)

You don't need very much--a few hundred parts per million. Both ionium and Pa-231 have huge neutron cross-sections, so they'll be pretty big targets in the fuel.

Denaturing Thorium with Ionium

Code:
        TOTAL   ELASTIC  FISSION  CAPTURE  half-life
Li-7    1.015   0.97     -        0.045    stable
Be-9    6.1586  6.1510   -        0.0076   stable
F-19    3.643   3.652    -        0.0096   stable
Th-230  32.32   9.774    0.0      22.55    75,400 yr
Th-232  21.11   13.70    0.0      7.40     14e9 yr
Th-233  1478.   13.0     15.0     1450.0   22.3 min
Pa-231  210.69   9.954   0.02     200.72   32,700 yr
Pa-232  1176.2  12.23    700.0    464.0    1.31 day
Pa-233  53.051  13.021   0.0      40.031   27.1 day
U-232   162.3   10.79    76.66    74.88    69.8 yr
U-233   588.38  11.97    531.16   45.25    159,000 yr
U-234   119.2   19.41    0.0062   99.75    245,000 yr
U-235   698.2   15.03    584.4    98.81    704e6 yr


There's probably not enough ionium in the world to spike all the thorium that would be needed for world power requirements. Ionium-spiked thorium would be especially useful for less-than-trustworthy places that want thorium power.


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PostPosted: Feb 22, 2007 10:31 pm 
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Kirk Sorensen wrote:
U-232 ruins the weapons potential of the U-233.
[....]
You don't need very much--a few hundred parts per million.

How does "a few hundred parts per million" of U-232 "ruin the weapons potential of U-233" ?

From what I've read, U-232 has some usefulness in deterring unsanctioned diversion by radiation spiking, not anything to do with the physics of nuke bombs.

But the penetrating gamma radiation does not come from U-232 itself, which is just an alpha emitter, with a 72y half-life.
Rather, it comes from two of the decay "daughters" in the long decay chain, which ends with Pb-208.
Specifically, the Bi-212 and Tl-208 decay chain "daughters" emit gammas of 0.7 to 2.6MeV.
This is comparable to many of the fission products in the fuel mix of the reactor.
Moreover, like the fission products, Bi-212 and Tl-208 are "cleaned" from the uranium, when it is chemically separated.
The chemical separation leaves perfectly viable, virtually non-radioactive, uranium bomb material.

The only catch is that unlike the fission products that are removed permanently, the Bi-212 and Tl-208 slowly grow back in again, after you've built your bomb, as the U-232 decays.
So while the gamma dose rate from your "spiked" bomb would be zero initially, one month after chemical separation it would rise to about 10 rems per hour (at one meter distance), and in one year it would be up to about 100 rems/hour.

I don't know about you, but it seems like a pretty poor deterrent to me, taking into account today's fanatical suicidal terrorists.

.


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PostPosted: Feb 22, 2007 10:41 pm 
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jaro wrote:
I don't know about you, but it seems like a pretty poor deterrent to me, taking into account today's fanatical suicidal terrorists.

U-232 is an excellent deterrent, in my opinion. You can't separate it from U-233, it follows the same decay chain as thorium-232 but it follows it 200 million times faster.

The gamma ray that comes off of thallium-208 is very penetrating, and would not only signal the location of the weapon to orbiting satellites but destroy the electronics of the weapon and possibly alter the chemistry of the chemical explosives through cross-linking and polymerization and so forth.

Yes, the U-232 doesn't actually screw up the nuclear detonation properties of the bomb, but if it screws up the explosives and the electronics, that has to be considered pretty effective too.

You can purify the uranium of daughter products, but that's going to involve disassembling the weapon, removing the pit, melting everything down and recasting it, in a remote hot-cell, mind you. And even after you do all this and make a new bomb with new electronics, after a week or so the decay chain has reformed and the gamma ray intensity is increasing, quickly, and that will destroy the new bomb you've built

Contrast this with the ease of building a bomb out of plutonium-239 or uranium-235, which are simple alpha emitters and easily shielded, and it's not hard to see why no one has ever built an operational nuclear weapon with uranium-233.


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PostPosted: Feb 22, 2007 11:01 pm 
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Kirk Sorensen wrote:
You can purify the uranium of daughter products, but that's going to involve disassembling the weapon, removing the pit, melting everything down and recasting it, in a remote hot-cell, mind you.

Terrorists may be fanatics, but they're not necessarily stupid, as pertains to technicalities.

Do you really believe they would go to the trouble of separating the U233 from the fission products & Tl-208, and then wait a month before using the bomb ?

Worse yet, because U has a very low neutron background, quite unlike Pu, no fancy implosion geometries and electronic gadgets are required -- a "wooden bomb" will work OK (unfortunately).


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PostPosted: Feb 22, 2007 11:03 pm 
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jaro wrote:
Terrorists may be fanatics, but they're not necessarily stupid, as pertains to technicalities.

Do you really believe they would go to the trouble of separating the U233 from the fission products & Tl-208, and then wait a month before using the bomb?

First of all, terrorists are stupid. In fact, experience would show that they're extremely stupid.

Second of all, I don't believe they'd go to the trouble to try to get U-232 contaminated U-233 when getting HEU or plutonium is SOOOO much easier.

Gun-type bombs take roughly 10 times as much weapons-grade material as an implosion bomb. Even stupid terrorists can do that math.

Furthermore, the alpha-activity of U-232 is going to require anyone thinking of a gun-type bomb to scrub any light element out that might undergo (alpha,neutron) reactions. Otherwise it won't work.


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PostPosted: Feb 23, 2007 6:32 am 
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How much U-233 would a gun type bomb need? 20 kg?


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PostPosted: Feb 23, 2007 7:04 am 
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20kg would be plenty for two.


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PostPosted: Feb 23, 2007 9:42 am 
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Kirk Sorensen wrote:
Furthermore, the alpha-activity of U-232 is going to require anyone thinking of a gun-type bomb to scrub any light element out that might undergo (alpha,neutron) reactions. Otherwise it won't work.

Reactor grade Pu has far more alpha decays than U233 spiked with U232, because it contains a larger fraction of Pu241 and Pu238 -- typically 13.2% Pu241 and 1.4% Pu238.
For additional info on reactor-grade plutonium, see my post on the web site of the Nuclear Waste Management Organisation (NWMO).

.


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