Fiestaware - Natural vs Depleted Uranium - Seriously This Time

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Go-Figure
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Fiestaware - Natural vs Depleted Uranium - Seriously This Time

Post by Go-Figure » 20 Jan 2020, 02:19

Today’s post is about the world famous Fiestaware, a line of ceramic glazed dinnerware manufactured in the United States since 1936, with a hiatus between 1973 and 1985.
According the New York Times “Fiestaware is the most collected brand of china in the United States. It's also the No. 1 selection for casual dinnerware in American bridal registries”.
https://www.nytimes.com/2002/12/01/maga ... green.html

The reason such an object is interesting to someone into gamma spectroscopy and radiation detection in general is that the red "Fiestas" pieces manufactured up until 1973 had Uranium Oxide in their glaze so they were pretty radioactive.
Between 1936 and 1943 Natural Uranium was used. Then, during WWII, the Manhattan Project started, the US government took control of Uranium and confiscated the company’s stocks of Uranium. The production of the red Fiestas stopped and only resumed in 1959, this time using depleted rather than natural Uranium.
In both cases the Uranium was chemically refined, so it did not contain all the products of the decay chain like Radium, Lead and Bismuth. Allegedly only the first isotope of the decay chain is present: Thorium 234, but the second makes an appearence here as well.

The difference between the pre-war and post-war pieces is the presence of Uranium 235, a lot more prominent in the pre-war pieces, containing natural Uranium.
I already posted a Fiestaware thread, but back then I had a few misconceptions about a thing or two.
viewtopic.php?f=5&t=522
To start with, the thread title was wrong, it reads “Depleted Uranium”, but the piece I tested was a pre-war one, containing natural, and not depleted Uranium.
So I decided to do a better, more complete test.

First of all I needed a Fiestaware containing depleted uranium, so I went after a post 1959 piece.
Checking ebay I found this saucer-cup set, dating back to the 60s according to the seller.
01 - DSC07640_FR.jpg


The initial inspection already revealed something strange, the saucer has what’s known as a wet foot, meaning the underside is completely glazed, you don't see any un-colored clay, while the cup has a dry foot ring.
I didn’t pay too much attention to it and I proceeded with the tests, starting with the saucer.
02 -DSC07641_FR.jpg
03 - DSC07643_FR.jpg
Nearly 33000 CPM on the Geiger was not a surprise, the other piece I have gave me a similar read.
04 - DSC07648R.jpg
Before recording a spectrum with the GS 2’’x2’’ I took a preliminary measurement of both pieces with the PDS 100G, three hours each. In order to have a good reference I also recorded a three hours spectrum of my other Fiestaware, the plate I tested back in September, containing natural Uranium.
The saucer’s spectrum left me pretty confused, it looked exactly like the plate’s, a clear indication that I was detecting natural Uranium again...did I waste my money?
The presence of natural Uranium means the saucer has been manufactured before 1943.

Here is the spectrum but in linear and logarithmic scale.
05 - Fiestaware Saucer - Natural Uranium - 10800 Secs - 311219 - çIN.png
06 - Fiestaware Saucer - Natural Uranium - 10800 Secs - 311219 - LOG.png
The 2’’x2’’ confirmed the saucer’s glaze had natural and not depleted uranium in it. You can tell by the prominence of the U235 peaks compared to the Th234 ones.
Protactinium 234 metastable was there as well with its two peaks at 766 keV and 1001 keV clearly visible in the “energy-per-bin” view.
Between the two Th234 peaks there’s another one at 77-80 keV, exactly where you would expect to find Lead X-Rays.

The spectrum is presented in both counts per bin and energy per bin view.
07 - Fiestaware Saucer - Natural U - ID - 5 Hours - BG Subtraction - Counts x Bin - No Shield - 0.03 Clean - 11-01-20.png
08 - Fiestaware Saucer - Natural U - ID - 5 Hours - BG Subtraction - Energy x Bin - No Shield - 0.03 Clean - 11-01-20.png
The Lead peak is not due to fluorescence from the shielding. I was expecting to find this peak and in order to be able to rule out any shield fluorescence I didn’t use any shielding for this measurement. The sample was active enough to be tested properly with a simple background subtraction.
09 - DSC07480R.jpg
So the Lead fluorescence peak comes from the saucer itself.
And now for the quantitative analysis, here’s the usual tab. It was several months since I measured the unshielded background of my measurements room, it didn’t change much since then, albeit a small change is there after all, it held stable at 256-259 CPS throughout many measurements across months. This time it was 251 CPS.
As for the sample: 438 CPS, but almost all of very low energy, therefore the measured exposure was the same I got from the background.
10 - Spectrum Analysis Saucer @Contact+1-001.jpg
Part 2 about the cup is on the way...
Last edited by Go-Figure on 21 Jan 2020, 03:53, edited 13 times in total.

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Re: Fiestaware - Natural vs Depleted Uranium - Seriously This Time

Post by Go-Figure » 20 Jan 2020, 02:29

Part 2

And then it was time to take care of the cup.
By the time I got there I started to think there was still a chance to find depleted Uranium in it, despite the saucer containing natural Uranium.
The difference in the foot could be an indication the two pieces maybe belonged to two different sets. Doing some research I found out post-war Fiestaware had dry foot, and my cup had dry foot so there was still hope.
01 - DSC07652_FR.jpg
02 - DSC07656_FR.jpg
03 - DSC07659R.jpg
The Geiger read 28000 CPM, less than the saucer, but that was largely dependent on the geometry of the cup not allowing me to put the pancake probe as close to the glaze as I it was to the saucer's.
And then....bingo! The three hour spectrum from the PDS revealed the presence of depleted Uranium at last. You can see the U235 peaks are much weaker than in the saucer’s spectrum.

Again, linear scale first, then logarithmic.
04 - Fiestaware Cup - Depleted Uranium - 10800 Secs - 311219 - LIN.png
05 - Fiestaware Cup - Depleted Uranium - 10800 Secs - 311219 - LOG.png
The GS 2’’x2’’ NaI(Tl) confirmed the result, the difference in strength of U235 peaks is unmistakable, with the rest of the spectrum being almost identical to the saucer’s, including the lead fluorescence peak, albeit less clear than in the previous measurement.

Again, counts per bin first, then energy per bin.
06 - Fiestaware Cup - Depleted U - ID - 5 Hours - BG Subtraction - Counts x Bin - No Shield - 0.03 Clean - 11-01-20.png
07 - Fiestaware Cup - Depleted U - ID - 5 Hours - BG Subtraction - Energy x Bin - No Shield - 0.03 Clean - 11-01-20.png
Again, no lead shield was used for this measurement, so no chance of residual fluorescence from it after the background subtraction. The X-Rays fluorescence comes from the cup.
08 - DSC07474R.jpg
The quantitative analysis reveals that I got a lot more counts from the cup than for the saucer, but again this is largely due to geometry: the size of the scintillator was just right to fit it inside the cup, allowing more material close to the crystal than in the saucer’s measurement.
The average energy per count was 5% less than that from the saucer, which was not a surprise for depleted Uranium vs natural Uranium.
09 - Spectrum Analysis Cup @Contact+1-001.jpg

So that’s it. Re-reading my first Fiestaware experiment I wasn't happy with it. This one was more satisfying. The goal was a comparison of natural and depleted Uranium. For a lucky coincidence I got both of them in the same set.

Until next time.

Massimo
Last edited by Go-Figure on 21 Jan 2020, 04:00, edited 5 times in total.

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pilgrim
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Re: Fiestaware - Natural vs Depleted Uranium - Seriously This Time

Post by pilgrim » 20 Jan 2020, 06:52

So Massimo, how could I understand if my piece of Fiestaware has depleted or natural Uranium inside if I don't have any other information about it and if I don't have another sample that surely contains DU for a comparison?
Reading your old thread I thought I understood that also the 77 keV xrf peak could reveal if the sample has DU o NU inside.
Daniel, Italy

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Re: Fiestaware - Natural vs Depleted Uranium - Seriously This Time

Post by Go-Figure » 20 Jan 2020, 07:15

pilgrim wrote:
20 Jan 2020, 06:52
So Massimo, how could I understand if my piece of Fiestaware has depleted or natural Uranium inside if I don't have any other information about it and if I don't have another sample that surely contains DU for a comparison?
Reading your old thread I thought I understood that also the 77 keV xrf peak could reveal if the sample has DU o NU inside.
It's all in the "strenght" of U235's peaks compared with the others, which makes sense since depleted Uranium means less U235 with the rest being more or less equal.
In the saucer's spectrum the 92 keV peak from Th234 is 2.5-3 times "taller" than the 186 keV peak from U235.
In the cup's spectrum the difference is much bigger, in the region of roughly 5 to 1.

I post them one next to the other so the difference is easier to see.
07 - Fiestaware Saucer - Natural U - ID - 5 Hours - BG Subtraction - Counts x Bin - No Shield - 0.03 Clean - 11-01-20.png
06 - Fiestaware Cup - Depleted U - ID - 5 Hours - BG Subtraction - Counts x Bin - No Shield - 0.03 Clean - 11-01-20.png
In the PDS spectra you can read the actual CPS in the vertical axis to make the comparison even more clear.

Massimo

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Re: Fiestaware - Natural vs Depleted Uranium - Seriously This Time

Post by Steven Sesselmann » 20 Jan 2020, 12:38

Massimo,

Thank you for the excellent report..

I noticed the Saucer has a little hump around 350 keV which seems to be missing in the cup, do you have any idea what it might be?

Steven

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Re: Fiestaware - Natural vs Depleted Uranium - Seriously This Time

Post by Go-Figure » 21 Jan 2020, 10:24

Steven Sesselmann wrote:
20 Jan 2020, 12:38
Massimo,

Thank you for the excellent report..

I noticed the Saucer has a little hump around 350 keV which seems to be missing in the cup, do you have any idea what it might be?

Steven
Yes, I noticed that too.
I don't know what it can be. Not yet at least!
I also would like to identify the small X-rays peak on the left. There's an U235 X-Ray thereabouts but right now I can't really tell.

Massimo

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Re: Fiestaware - Natural vs Depleted Uranium - Seriously This Time

Post by Sparky » 27 Jan 2020, 00:53

Here is another example, just for reference. I used two bowls of similar size, and took the spectrums from the “foot” end to minimize differences in presentation to the probe. The DU Bowl is Fiestaware from 1959 or later and the NU bowl is “Harlequin”, a lower cost line from the same manufacturer which was probably made in the 1930s.

The NU Harlequin Bowl is pretty hot, about 44,000 cpm from the top side. I don’t really know why it is so much hotter than the Fiestaware. Almost all of these counts are coming from betas from the early daughters of U238. NU/DU should not make a difference. Anyway, these are the rates:

Fiestaware:
Pancake GM Probe: 33,000 cpm (foot end)
38mm Scintillator: 510 cps

Harlequin:
Pancake GM Probe: 42,000 cpm (foot end)
38mm Scintillator: 690 cps

Regarding the slight indication at 350 KeV, I am pretty sure this is Pb214 (351 keV) coming in from background. I checked with a U decay calculator to see if any Pb214 could grow in after 90-100 years and the answer is no.

https://www.wise-uranium.org/rccu.html

Mike Loughlin
Attachments
Two_Bowls.JPG
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Probe Presentation.JPG
DU Vs NU 01252020.png
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Re: Fiestaware - Natural vs Depleted Uranium - Seriously This Time

Post by Go-Figure » 27 Jan 2020, 20:16

Sparky wrote:
27 Jan 2020, 00:53
Regarding the slight indication at 350 KeV, I am pretty sure this is Pb214 (351 keV) coming in from background. I checked with a U decay calculator to see if any Pb214 could grow in after 90-100 years and the answer is no.

https://www.wise-uranium.org/rccu.html

Mike Loughlin
That's a very good link Mike!
As for the peaks, I too excluded Pb214 from the sample, but it also seems strange to me that it's coming from the background. In my experience, even with weaker samples than these ones, I never had visible residual Pb214 peaks from the background once it was subtracted.
Anyway, I can repeat the test with shielding+background subtraction to see if there's any change there.

Massimo

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Re: Fiestaware - Natural vs Depleted Uranium - Seriously This Time

Post by Sparky » 29 Jan 2020, 00:14

That little bump at 350 is a bit mysterious. I agree it really doesn't look like the PB214 photo-peak one sees with a Background spectrum. I notice it in both our NU spectrums.
Maybe the Uranium used the 1930s wasn't fully separated from all its progeny. DU is a byproduct of Enrichment and I am guessing it is very clean.

Mike Loughlin
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