Posts Tagged ‘radioactive’

h1

A Nuclear Jockstrap

February 3, 2017

Note: Click on any image for a larger version and a caption.

William J. A. Bailey (1884-1949) was a quack-cure huckster.  After dropping out of Harvard without a degree, he briefly engaged in mail fraud, served a prison term, and then entered the lucrative and minimally-regulated patent medicine trade with a fraudulent European doctorate.  His chosen specialty was “male enhancement.” (As anyone with an email account will attest, this dubious market has survived the intervening century and all attempts at regulation.)  Bailey’s first boner pills contained strychnine.  He entered business at a time when popular enthusiasm for radioactivity was ascendant, and he is mostly remembered today for his lethal radioactive quack cures, including Radithor and the Radiendocrinator (above).  Most hucksters did not actually include radioactive ingredients in their products; they lied.  On this matter, though, Bailey was deadly honest.  Evidence suggests he used his own products, believed in them, and in all possibility, died from them (bladder cancer).

The Radiendocrinator is a credit-card-sized radium source of spectacular activity (originally 100 microcuries of Ra-226 and 150 microcuries of Ra-228) intended to be stuffed into a man’s jockstrap and worn “under the scrotum” for extended duration. Production spanned 1922-1929, and with prices set in the thousands of dollars (1929 basis), only the Jay Gatsby set could afford these gilded nut-roasters. Users were instructed to orient the wire-mesh window towards the skin to ensure maximum beta dose to shallow tissues.  In measurements on my Radiendocrinator (and it must be noted that the Ra-228 is long gone now and only Ra-226 remains), the beta-gamma reading on a Fluke 451B ion chamber was 390 mR/h at 1/8 inch, and the gamma-only reading was 52 mR/h.  It is not straightforward to extract a beta dose rate from such measurements, but assuming a correction factor of ~0.1 Gy/R (dependent on beta energy, source geometry, and ion chamber geometry), a total scrotal skin and gonadal dose rate of 30-40 mGy/h is probably not unreasonable.  Far from causing a boost to male potency, wearing a Radiendocrinator according to the manufacturer’s instructions would have likely led to temporary sterility and, of course, elevated risk of cancer.  In other words, it was a male contraceptive of sorts.  As an unsealed radium source, the wearer’s clothing, nutsack, schlong, bedsheets, sexual partners, and probably anything in the vicinity would have been rendered contaminated by Pb-210, Po-210 and other radon daughters.  Lord, what a mess.

Modern owners of these radioactive collectibles should be cautious about proper storage, as they are among the hotter of the classic quack radium cures.  Most important is a hermetic container (e.g., a small dive box) to control radon daughters emitted from the source itself.  The blue velvet-lined Radiendocrinator case is likely to be roaring with radon daughter activity as well, and should be kept separately in a bag or other sealed container.  Shielding from the penetrating gamma radiation is strongly advised.  2-4 cm of lead is reasonably effective.  The source and its case should only be handled with gloves and the source itself should NEVER be opened except in a radiochemical glovebox facility, as there is a grave risk of airborne radium alpha activity being liberated.

UPDATE: VARSKIN 4 model

The question of dosimetry from a Radiendocrinator continues to interest me because of how high the doses could potentially be from this particular device in its suggested mode of long-term use pressed against the skin.  To provide more insight into the doses, I downloaded VARSKIN 4, a deterministic radiation transport tool developed for the US NRC often used to model beta doses to skin, and I modeled the geometry and source activity of a Radiendocrinator at the peak of its beta-emitting powers (which occurs when it is 3.5 years old).  The model makes numerous assumptions, and some may not be very good:

  • Source area is the Radiendocrinator’s front “window,” 6.23 cm long and 3.63 cm wide (measured).
  • The source itself is 7 sheets of absorbent paper uniformly loaded with radium sulfate, 0.33 mm thick each, with a density of 0.55 g/cc.  The paper’s density and thickness are a total guess.  The number of source sheets is borrowed from Paul Frame’s online description of the innards of his device.  Note: NEVER TAKE ONE OF THESE APART (unless, like Paul Frame, you have the facilities to handle a loose alpha source of this intensity).  Initial activity of 100 μCi Ra-226 and 150 μCi Ra-228 were inferred from Kolb’s and Frame’s description in Living with Radiation: The First Hundred Years.
  • At the time of peak beta intensity–when the source is 3.5 years old–it will contain the following important beta-gamma activities:
    • Pb-214, 100 μCi
    • Bi-214, 100 μCi
    • Ac-228, 98.4 μCi
    • Pb-212, 84.2 μCi
    • Bi-212, 84.2 μCi
    • Tl-208, 30.3 μCi
  • Pb-210 and Bi-210 are omitted as they will not have had much opportunity to grow in at 3.5 years.  Alpha emitters are omitted.
  • There are two overlain sheets of 16-mesh woven metal screen composed of 0.009-inch wire that are interposed between the source material and the human target.  VARSKIN does not model such geometries. I calculate a transparency of 53%, and assume the metal blocks 100% of intercepted beta particles and 0% of intercepted photons.
  • There is a plastic sheet, probably nitrocellulose, over the front of the device that I model in VARSKIN as 0.5 mm thick with a density of 1.3 g/cc.  This is a total guess.
  • I assume a 1-mm gap between the source and skin.
  • VARSKIN’s default skin dose averaging area is 10 sq. cm., in recognition of the US NRC’s current rule for computing shallow dose equivalent in 10 CFR 20.1201(c).  I did not alter this in the calculation.

Results: In vintage condition (3.5 years old), the Radiendocrinator’s predicted shallow dose rate due to beta particles is 88 mGy/h, and with the gamma contribution added in is up to 91 mGy/h.  Deep dose rate (from gamma contributions only) is 2.0 mGy/h.  In the Radiendocrinator’s present condition, assuming the contributions of ingrown Bi-210 and the total decay of the Ra-228 chain, the beta-gamma shallow dose rate is 57 mGy/h, and the deep dose rate is 0.9 mGy/h.  So…what does this mean, practically, for the wearer?

  • 2 Gy is the threshold for skin erythema: waves of redness and itching sensation over several months, culminating in skin death and replacement as in a sunburn.  The Radiendocrinator wearer potentially earns an itchy, inflamed scrotum with a few nights of wearing the device.
  • 15 Gy marks the onset of painful burning with moist desquamation following browning of the skin, i.e. a “nuclear tan”, with the possibility of long-lasting ulceration.  This is a hardcore radiation burn.  If you wore the Radiendocrinator all the time, every day, for a week, this might be your reward.  As there are no records of gruesome and agonizing injuries associated with the device, I assume there were no users hardcore enough to “ride the radium” full-time.
  • Temporary sterility can happen with doses of 150 mGy or greater to the testes.  With a deep dose rate of 2 mGy/h, it would take a guy three whole days on the nuclear pad to achieve temporary sterility.  Libido would not be impacted.
  • Stochastic effects: using ICRP weighting factors, I calculate an effective dose rate of about 1.2 mSv/h from the skin (shallow) and deep (general tissue) dose rates given above.  The excess risk of fatal cancer is on the order of 5%/Sv.  Though the dose rate is on the higher side, your real problem with this source is the skin damage you would endure.
h1

Herb Anderson’s “Live Block” of the Chicago Pile

June 4, 2016

DSCF3105_v1

They don’t give out spent nuclear fuel as a memento anymore.  But on the tenth anniversary of the first nuclear reactor (the Chicago Pile) going critical, pile physicist Herbert L. Anderson was presented with this handsome “live block” of graphite and uranium metal fuel, piping hot and right out of the reactor core.  With an estimated two millicuries of Cs-137 then distinguishing it from the natural uranium whence it was made, the unique artifact spent the next sixty years as part of Anderson’s home decor, a reminder of his pivotal role in one of the 20th century’s greatest triumphs in physics.  Herb’s wife Betsy kindly gave it to me in 2014 with the hope that new understanding and appreciation would follow.

Now, having had nearly two years to get to know this artifact, I can share some preliminary findings about it–and a few lingering questions as well.  I am grateful for ongoing partnerships with the University of Missouri and the Vinca Institute of Nuclear Sciences that are bringing new details to light about its metallurgy and history, and I am grateful for past assistance from the University of New Mexico here in Albuquerque.  I am actively searching for ways to bring this piece of the first reactor to an appreciative public audience.  So, dear reader, if you have suggestions or information that will help with either the technical understanding of the artifact, or its accommodation in a museum for the upcoming 75th anniversary of the Manhattan Project, please get in touch.

Part I: Basic physical description

DSCF3005_v1

This is a “live block” (meaning a piece of graphite with nuclear fuel installed in it), distinguished from the “dead blocks” of pure graphite that were interspersed or used as reflectors in the Chicago Pile.  Several museums possess “dead blocks”; to my knowledge, these include the American Museum of Science and Energy (Oak Ridge), the Bradbury Science Museum (Los Alamos), the National Atomic Testing Museum (Las Vegas), and the National Museum of Nuclear Science and History (Albuquerque).  My friend Kelly Michaels has an excellent photo set of these artifacts.  Pieces of Chicago Pile fuel also survive independently;  most notably, this piece once belonging to Alvin Weinberg.  However, the Herb Anderson “live block” is unique, to my knowledge, in that it contains fuel and moderator together.  The block’s measured dimensions, including fuel dimensions and those of the decorative housing, are available in a SolidWorks model to interested parties (please contact me).

The “T01” lot stamp appearing on the right face of the graphite block indicates that the graphite is AGOT made by the National Carbon Company, one of at least six types of graphite used to build the Pile.  AGOT had the lowest neutron absorption of all of these types, so was preferred for the pile’s core region.  About 2/3 of the CP-1 pile consisted of AGOT.  This grade of nuclear graphite went on to be used in the Graphite Reactor at Oak Ridge and the plutonium production reactors at Hanford.

The fuel is unclad uranium metal in cylindrical elements that bear identifying stamp marks on the front faces.  When I replaced the original cracked acrylic housing around the artifact, I was able to weigh the fuel elements directly.  The left element weighed 2.564 kg, and the right one, 2.553 kg.  The left element stamp reads “M230/L101/P2” while the right one reads “M170/L79/P1”.  The significance of these marks remains unknown to me.  I believe that if someone is able to assist in their interpretation, we might learn which of the three recorded contributing manufacturers of U metal produced this fuel.  It should be noted that metal fuel was a small minority of the Chicago Pile fuel, amounting to just 5.4 metric tons; the vast majority of the fuel was pressed-oxide “pseudosphere” elements.  Metal was made variously by Westinghouse, Metal Hydrides Corp., or the Ames Process.

Another question raised by this artifact is that it contains cylindrical metal fuel placed into chamfered recesses in the graphite designed for receiving “pseudosphere” oxide fuel.  As such, the cylinders cannot remain centered or upright in the recesses without the assistance of some acrylic supports that may be seen in the x-ray image.  I am quite sure that acrylic was not part of the original pile construction!  One is tempted to question, then, whether this fuel-and-stringer combination is original.  It could be that most graphite live blocks were machined for pseudosphere fuel, but when metal became available, the pseudosphere live blocks were used anyway (perhaps with graphite inserts serving the mechanical function of the acrylic supports, which begs the question of why the artifact contains acrylic instead; or perhaps without any supports, the fuel cylinders simply being dropped awkwardly into the recesses).  A lack of detailed photos from the construction of CP-1 makes the question hard to answer.

Part II: Gamma spectrometric estimate of fuel burnup

gammaspec_150704

Mentioned earlier is the fact that this fuel contains cesium-137.  In fact, the external radiation signatures are dominated by this long-lived fission product.  Without a doubt, then, the fuel has been significantly exposed to reactor operation.  By comparing count rates in the Pa-234m gamma peaks to that in the Cs-137 peak at 662 keV, we can determine the quantity of Cs-137 remaining in the fuel under the assumption that the Pa-234m is in equilibrium with its U-238 parent.  This will motivate the estimation of fuel burnup range under various assumptions about the artifact’s history.  I performed the requisite experiments with my PGT germanium detector and obtained the spectrum shown above, leading to an estimated activity of 540 microcuries of Cs-137 distributed throughout the total fuel at the time of measurement.  Here are a few historical scenarios and the fuel burnup roughly corresponding to them:

  • The fuel operates in CP-1 only (December 1942-February 1943):  163 kWd/MTU
  • The fuel operates in CP-1 and its reconstruction in the Red Gate Woods (CP-2), and is removed from the operating reactor before being presented to Herb Anderson in November 1952 at the Tenth Anniversary celebration in Chicago: 132 kWd/MTU
  • The fuel was removed from the pile (CP-2) when it was decommissioned in 1954, and somehow was then integrated into the artifact: 127 kWd/MTU

There are challenges with all three potential histories.  The first is very unrealistic, given the known operating conditions of CP-1 in the brief months it was in use.  Intermittently critical, with a peak power of ~200 W achieved on one day only, the burnup in the fuel attested by these calculations is many thousands of times greater than what is possible according to the conventional history of that Pile.  The second scenario is supported by both the burnup calculation (even though I am aware of no formal operating records from CP-2) and the description given by Mrs. Anderson of how Herb got the item, but it leads to two big puzzles, firstly concerning how the fuel was removed from the reactor while the reactor was still in service, as the pile was not designed to be easily disassembled in the CP-2 instantiation; and secondly concerning the high activity levels of the discharged fuel when it must have been released from government custody to Anderson.  The third explanation avoids the issue of taking apart the reactor just to obtain a souvenir as the reactor was disassembled during decommissioning; however, it is historically inconsistent with the story told by Mrs. Anderson.  So what this gamma spectrometry measurement allows us to say with certainty is that the fuel was used in CP-2 (as well as the original pile, presumably).  Beyond that, plenty of thought-provoking questions remain.

Part III: Neutron multiplication properties

It would seem there is no greater aspiration for a piece of the world’s first nuclear reactor than to return, momentarily, to the task originally undertaken with so much fanfare: multiplying neutrons in fission chain reactions.  These three photos above show some multichannel-scaling apparatus to look at fission in the CP-1 block (set up in my kitchen, because this is a “cooking” project of sorts).  We are going to examine the time correlation between neutron counts in a bank of two He-3 proportional counters next to our specimen.  Both counter tubes and the specimen are reflected by polyethylene blocks to trap neutrons in the system as best we can.  Highly-correlated counts point to fission “chains”, in which a fission event causatively leads to successive ones on a time scale controlled by the neutron transport properties of the specimen and surroundings.  I’ll measure correlation by way of excess variance, or the Feynman Y-statistic: the difference between the measured variance-to-mean ratio of counts accumulated in a certain time window interval and unity (which corresponds to idealized, uncorrelated, Poisson-distributed counts).  We’ll look at the CP-1 live block by itself and with a small additional neutron source present.  We will also look at the neutron source alone, a lead brick, and the empty polyethylene cavity.  Results and commentary below.

So what the fuck does this mean?  Firstly, the CP-1 block by itself produces strongly time-correlated neutrons (purple data) on a measurement scale of about a millisecond or greater, while the little homemade AmBe neutron source is pretty much stochastic (red data).  (Note, though, that the AmBe source is about five times stronger a neutron source than the block.)  Putting the block in with the AmBe source slightly reduces the neutron count (~12%) versus the source alone, but produces excess correlation of nearly 30% of the block by itself, indicating the presence of induced fission.  The high correlation in the block itself may be attributed to spontaneous fission (SF) as a minor decay mode of U-238, as well as a smaller contribution of spallation and fission induced by secondary cosmic rays.  These neutron sources each produce a burst of neutrons, and are also closely coupled to successive induced fissions.  The AmBe source, by contrast, is driven by radioactive decay: alpha particles slam into beryllium.  Notice the curvature of the data in all cases: it rises as we lengthen the counting window.  That is to say, there is more neutron correlation as the window gets longer.  Neutrons take their time moving through materials, scattering, slowing down, and finally reaching the detector, and neutrons produced in coincidence will not register as such unless the window is long enough to account for their random meanderings through material.  Finally, just to illustrate fission and other fission-like reactions in something other than uranium, I put a 20-pound lead brick in the counter.  Now you may believe that lead is not a fissionable material, but under the right conditions–such as when a 500-MeV electron in the secondary cosmic ray spectrum hits it–the lead nucleus can split up by fission or by a somewhat similar process called spallation, cooking off a distribution of neutrons.  And that is why we see highly-correlated neutrons (green data) being emitted by lead.  Again note the upper right graph, though: lead is a very weak source of neutrons even though the ones that are emitted are highly time-correlated.

h1

Videos from my recent trip to Chernobyl

September 17, 2011

Two videos from my most recent radioactive scavenger hunt in Ukraine’s Chernobyl exclusion zone are now on YouTube.  One features a pinhead-sized piece of spent nuclear fuel (pictured at left) that was carefully excavated from under about six inches of soil with the aid of a CDV-700 Geiger counter probe, taken back to our hotel through Checkpoint Lelev (where the scintillation portal monitor was conveniently out of service), and analyzed using a scintillation detector and Marek Dolleiser’s “PRA” software—a clever MCA emulator that uses one’s computer audio device as a nuclear ADC.  Check it out (I recommend selecting the HD format at the bottom of the window):

The second video illustrates some environmental radiochemistry at work, namely the affinity of the beta emitter Sr-90 for the phosphate matrix of deer antlers.  In this video I show that although the gamma activity (i.e. Cs-137 activity) in a pair of shed antlers is no different than local background, the beta activity is much higher.  The reasons for Sr-90’s notoriety are tangibly apparent: a decades-long half life that keeps it cracklin’ long after the accident, and alkaline-earth chemistry that favors uptake in bone.

h1

Nuclear Collection (Part VI)

March 13, 2011

Click any thumbnail image to view in full size. And, as always, if you have something radioactive and in need of a good home, contact me: I buy and trade all the time. Enjoy!

Lithograph by Leo Vartanian commemorating the CP-1 nuclear reactor.  In what has to be the winningest art idea ever,  moderator graphite from the historic reactor was actually ground up to make the ink in which the portraits of physicists Leo Szilard, Arthur Compton, Enrico Fermi, and Eugene Wigner were rendered.  Prints were distributed by Argonne National Laboratory to honor long and illustrious careers.  The ink is not detectably radioactive.  See my other mementos of CP-1 here. Size is 17″ by 22″(framed).

Though it is in many ways a modern and progressive nation, Japan steadfastly clings to certain curious anachronisms.  From the land of whaling and sailor-suit school uniforms come these examples of radioactive “quack cures”, modern instances of a fad phenomenon that, half a century ago, had largely been driven into extinction in the US and Europe.  Both items pictured—the Wellrich Co. Ltd. “Health Card” (top) and the “Mainasu ION” plaque (bottom)—contain natural thorium as verified by gamma spectrometry.    The “Health Card” claims to offer benefits that include denaturing nicotine in cigarettes.  The health benefits of the negative ion disk aren’t mentioned on it, but surely have no basis in sound science.  It is equipped with an adhesive surface on the back for mounting.  Dozens of varieties of negative ion quack products are peddled by Asian eBay sellers, and I have no idea how many of these items might be radioactive.  The Wellrich card and the ion disk measure 1400 CPM and 550 CPM respectively on a Ludlum 44-9 pancake Geiger tube.  (Donated to my collection by Bill Kolb.)

.

.

.

More radioactive vacuum tubes. All the specimens in this batch were kindly donated anonymously, and all are receiver protection tubes for military radar sets.  In this application, gas breakdown, aided by deliberately-included radioactivity, dissipates any high-power RF energy that finds its way into the receiver waveguide.  From left to right in the top photo: Varian MA37002X with Co-60 (originally “0.7 microcuries max.”), date code 1995; Omni-Wave MPT-24 with (originally) 25.0 microcuries of Kr-85, date code 1984; Omni-Wave MPT-47-B with (originally) 25.0 microcuries Kr-85, date code 1976.  The gamma spectra of the two Kr-85 tubes clearly shows the residual 514-keV gamma activity of the 10.8-year fission product and even permits a coarse estimate of the quantity remaining (about 3 microcuries in the MPT-24, 0.2 microcuries in the MPT-47-B).  More radioactive tubes are described here and here.

Large receiver protection tube with tritium. The application is the same as the tubes mentioned above, but this one is a monster, measuring almost 16 inches in length.  The part number is MA3948L-12, the manufacturer is Varian, and the contents are mostly argon and a small amount of radioactive tritium (H-3), 10 mCi.  The second photo shows an electrodeless RF discharge established in the tube.
… … … … … … … … … … … … … … … … … … … .. ….. … ….. … ….. ….. ….. ….. ….. ….. ….. ….. ….. ….. ….. ….. ….. …..

.

.

.

.

.

.

.

.

.

Contaminated Geiger counter strap from Chernobyl trip. Last summer’s trip to Pripyat resulted in detectable radioactive contamination of my shoes (see description) as well as this shoulder strap.  Gamma spectrometry easily identifies Cs-137, one of the handful of long-lived fission products, in a hot spot on the strap.  The activity in the spot is small, only about one nanocurie (~35 Bq).  Some possible contribution from the synthetic transuranic americium-241 is also noted.

h1

Radioactive Treasure in Bayo Canyon

November 11, 2010

Bayo Canyon, near Los Alamos, NM, was a testing ground for radioactive explosives during and after the Manhattan Project. Unfortunately, though it is public land now, it isn’t the most accessible place.  This photo depicts the canyon from its western rim last fall when I tried to get in with a friend.  The deep snow was a show-stopper on the trail leading down from the town on that day.  There is an access road that enters the canyon and provides for an easy walk to the blast sites, but it is gated, and unauthorized vehicles lured in by an open gate may find it locked when attempting to exit.  In spite of the hassle, however, I can now attest that Bayo Canyon is a bona fide destination for radioactive collectibles.

I returned to Bayo Canyon in the company of Taylor Wilson on October 16, and discovered my first radioactive token from this locality—a short piece of shielded two-conductor cable that reads about 600 CPM on a 2″ pancake Geiger tube.  It’s not screaming hot, but it means there’s more here.  (Photo credit: Tom Clynes; used with permission).

Los Alamos’ TA-10 facility in Bayo Canyon entered its decommissioning phase in 1960, and since then the canyon floor has been subject to sustained scrutiny from cleanup crews.  However, it’s obviously true that a persistent and focused hobbyist with good radiation detection equipment can beat a veritable army of government nine-to-fivers when it comes to truffling out the good stuff.  The DOE’s Radiological Survey of the Bayo Canyon, Los Alamos Final Report (1979) explains the nature of the residual contamination:

Because of the wide dispersal of debris by the tests and continuing natural erosion processes, it was recognized at the time of decommissioning that there was a reasonable probability that some high-explosive and some potentially radioactive materials remained in the canyon.  Thus, periodic surface surveys and searches were conducted in 1966, ’67, ’69, ’71, ’73, ’75, and ’76.  During such surveys a number of additional pieces of debris were located, with only a few of them being contaminated with “°Sr or including normal or depleted uranium.

Indeed there are many remaining pieces of debris, often entertaining in their own right if not detectably radioactive.  The pieces of metal in this last photo are representative; both exhibit extreme distortion from the force of whatever blast hurled them through the woods sixty years ago.

h1

Nuclear Collection (Part V)

May 13, 2010

Today’s long menu includes more radioactive pottery, more radioactive vacuum tubes, smoke detectors, a couple lesser-known radioactive elements, and a few interesting odds and ends. As always, if you have something radioactive and in need of a good home, I buy and trade all the time.  Enjoy!

Uranium-glazed artistic pottery is hard to come by, in contrast to the mass-produced (and mass-collected) Fiestaware and similar.  Here are two examples of handmade ceramics.  Especially interesting is a vase made in 2010 (left) that is representative of the work of crystalline-glaze artist William Melstrom, who has a studio in Austin, Texas (photo courtesy of Mr. Melstrom).  Melstrom is one of very few contemporary artists who have gone to the lengths required nowadays to work with uranium.  His adventuresome report on obtaining uranium compounds in France to formulate his glazes is a must-read.  The fluorescent light yellow glaze on this vase clocks in at 2200 CPM on a 2″ pancake GM tube.  At right is a hand-thrown and hand-glazed  decorative bowl from an unknown artist containing a typical “uranium red” glaze.  It registers 38,000 CPM on a 2″ pancake GM tube, making it among the hottest pieces of pottery in my collection.

.

These raw ceramic underglazes containing uranium are a gift from William Melstrom, who made the vase pictured above.  Before Melstrom owned them, they were in the possession of a radiation safety officer at the Texas Department of State Health Services, slated for official disposal as radioactive waste.  Because so few artists use or even know about uranium glazes now, old bottles such as these sometimes present surprise disposal problems when studios are cleaned out.  Both are products of Thompson Enamel and both read about 12,000 CPM on a 2″ pancake GM tube.  At left is a “531 Burnt Orange” (when fired, of course), and at right is a “108 Forsythia.”

.

This is a 6″ Corning uranium-glass optical filter I recently obtained on eBay.  The uranium concentration is through the roof: it emits 11,000 CPM into a 2″ pancake GM tube, making it more than twice as hot as the hottest decorative vaseline glass items I own.

Some other interesting properties of uranium glass are dramatically demonstrated with this example.  In the second photo, ultraviolet light from a distant Sun-Kraft lamp (an electrodeless quartz-mercury discharge tube) excites the uranium glass, provoking the characteristic green fluorescence.  Based absorption of the  lamp’s harsh 254-nanometer UVC radiation, it’s easy to distinguish a quartz crucible (casting the central shadow) from the nearly-opaque borosilicate tube (left) and soda-lime glass vial (right).

Uranium glass is also apparently a fair scintillation medium.  In the lower photo, a thin face of the Corning filter abuts the output window of a commercial x-ray machine, where exposure rates are on the order of 1000 roentgen / hour.  The glass glows its characteristic green color as the x-ray beam expands across its surface.

.

Lanthanum and lutetium are two of the lesser-known natural radioactive elements.  Although there are other natural, primordial radioelements (e.g. V-50, Rb-87, Sm-147, Re-187, In-115), these two stand out (along with good old potassium) for their usefully high gamma activity.   Both could be used as check sources or energy calibration sources for scintillation detectors.  La-138 (0.09% abundance, T1/2 = 1.02E+11 y) decays by electron capture or beta emission, unleashing gamma rays in either branch.  A ~50-g specimen of the metal (inset, left) racked up 7.2 counts / sec above background into a 2″ NaI:Tl detector.  Lu-176 (2.6% abundance, T1/2 = 3.78E+10 y) undergoes beta decay with a high yield of several gamma energies, most notably at 202 and 307 keV.  The peak at 509 keV in the spectrum is not a real gamma energy, but rather a “sum peak” caused by 202- and 307-keV gammas simultaneously entering the detector (this happens to be an “anomalous” sum peak, larger than would occur by random summation, precisely because the two radiations involved are frequently part of the same decay sequence).  The 23-g chunk of lutetium in the right inset veritably boils a 2″ NaI:Tl detector with more than 120 counts / sec above background.

.

More radioactive vacuum tubes. At right are three similar radar TR switches and their packaging (left to right: Bomac JAN-CBNQ-5883 from 1961 originally containing 0.3 µCi of Co-60; a Westinghouse 1B37 from 1952 containing several µCi or Ra-226; a GE 1B35 containing a small amount of Co-60.  At left, a spark gap (in hand) originally with 5 µCi of Cs-137 and a dual TR switch originally containing less than 0.7 µCi of Co-60.

.

Ionization smoke detectors contain an alpha emitter, typically Am-241.  The left-most pic shows industrial smoke detectors from ca. 1960, each containing a total of 80 microcuries of Am-241.  These detectors measured the current imbalance between an exposed “sense chamber” and a sealed “reference chamber,” both of which contained alpha sources.  In front of the detectors are examples of their sense-chamber sources, which hold the greater amount of activity (~60 microcuries).  Left is a Pyrotronics F5-B4 with its annular source holder bearing six thin sealed sources; at right is an F3/5A and its pedestal source, containing a single foil covered by a screw-adjustable bonnet.  More modern detectors are shown in the upper-right image: At left is a Simplex 2098-9508 with 4.5 µCi of Am-241, manufactured in 1980, and at right a run-of-the-mill modern detector with the typical  1-µCi source.  The lower right photo shows a Ra-226 foil source from a batch of smoke detectors, make unknown, that was intercepted on its way into a Pennsylvania junkyard.  Approximate activity is 1 microcurie.

.

Tritium glow-in-the-dark devices include emergency exit signage and the button at right.  Self-luminous exit signs are undoubtedly the most radioactive items in peoples’ everyday experience, but few probably realize it.   They can contain up to 20 curies of H-3 (tritium) gas in the glowing phosphor-lined tubes, as does the example shown here.  They are regulated under a General License by the Nuclear Regulatory Commission (see yellow sticker in right image).  Though initially costly, these self-powered signs easily deliver value over the life of a building by eliminating the need to conduct tests and change light bulbs.  Numerous outlets sell them on the Internet; they can also frequently be found at bargain prices on eBay (when the NRC isn’t looking).   The lower pic shows an old luminous button that originally contained 0.1 Ci of tritium.  This item replaced more hazardous predecessors containing radium.   Common consumer goods containing tritium today include “Traser” keychain lights (technically illegal in the USA as a “frivolous use” of radioactive material) and Trijicon gun sights.

.

Kodak 8-mm film projector (left) and camera (right) with radioactive thorium lenses. High refractive index and low dispersion justified the use of thoria in optical glass formulations.  The film projector’s 22-mm, f/1.0 Projection Ektar lens clocks in at 1200 CPM on contact with a 2″ pancake GM tube, while the camera’s lens only reads about 250 CPM.

.

Radium postcard, ca. 1930, from Luther Gable quack outfit. Ah, the good old days when you could just send loose radioactive contamination through the freaking mail! This postcard bearing a dollop of glow-in-the-dark radium paint (11,000 CPM on a 2″ pancake GM tube) promoted Dr. Luther Gable, the man responsible for the notorious Gable Ionic Charger.  A number of these cards were found in a collection of magician’s tricks.

.

The “Becquerel Chemicals” educational kit manufactured by Damon contains six small plastic boxes labeled A through F.  The contents of three are yellow powders, the contents of the other three are white crystals.  Students were intended to exploit physical and chemical properties—including radioactivity—to identify these unknowns from a list consisting of uranyl sulfate, sodium sulfate, uranyl nitrate, sodium nitrate, thorium nitrate, and sulfur.

h1

Nuclear Collection (Part IV)

January 12, 2010

Radioactive pottery and glassware are ubiquitous at antique malls.  Most items are affordable,  attractive, and retain their utilitarian function for serving food and beverages.  Plus, it’s always fun to pass a Geiger counter over a dinner guest’s plate just after the meal is finished and watch his face as the counter roars.  The vast majority of such articles can be categorized as shown below.  Uranium is present in their composition as a colorant and the radioactivity is merely incidental.  Some ceramic quack health products were intentionally radioactive.  My collection is by no means exhaustive, but is fairly representative of what a few weekends in local flea markets can turn up.

The red stuff owes its distinctive color to a leaded uranium glaze.  This glaze is most frequently encountered in so-called “California pottery” of the 1930s-50s, a style featuring bright, solid colors evocative of Moorish tile.  The best-known example is Fiesta made by the Homer Laughlin China Company.  Red Fiestaware contained natural uranium from 1936 to 1943, when wartime demand for uranium stopped production.  Production resumed in 1959 with depleted uranium and ended for good in 1972.  The selection in the photo at left includes Fiesta, as well as items made by Bauer, California Pottery, Pacific, and various unknown potteries.  Uranium red glazes can produce up to about 30 kcpm on a 2″ pancake Geiger detector.  Some kinds of California pottery are collectible and command high prices (e.g. Fiesta), but many uranium-glazed items of lesser pedigree can be found that cost no more than a couple dollars.

The yellow stuff, glazed with a transparent uranium glaze, is generally much less radioactive than the red (ranges up to about 5 kcpm on a 2″ pancake Geiger detector), and more stylistically diverse.  Examples of the California style can be found (the Franciscan Ware cup and saucer at left), but so can fine English bone china (small Paragon pitcher at center back), floral-patterned ware (Hall’s pitcher; Limoges “Golden Glow” plate, center-right) even special childrens’ dishes (front, with romantic verse and decal).  In general, the deeper the yellow tint, the hotter the product.  Most fluoresce a greenish tint under ultraviolet light.

The green stuff is uranium glass, made by including a highly variable amount of uranium oxide in the melt.  Colors range from amber to blue-green; some is transparent, some opaque.  Regardless of color or opacity, almost all fluoresces brilliant green under ultraviolet light.  Major sub-varieties are known as vaseline glass, jadeite, custard glass, and canary glass.  Uranium green glass was especially popular during the Great Depression; “elegant glass” and the cheaper “Depression glass” of a green color frequently contain some uranium.  Cullet, tubing, and marbles of modern production are widely available.  Uranium glass was also once widely used in making graded glass-to-metal seals because of a favorable coefficient of thermal expansion.  Its use in that application is represented by the Eimac 35-TG vacuum tube at right.  The hottest specimen in this tableau is the large hand-blown vase.  Though not particularly fluorescent, it puts out 5 kcpm into a 2″ pancake Geiger counter.

Quack crockery. “Revigators”  made in the 1920s are still surprisingly (frighteningly!) commonplace.   They were to Americans of the flapper age what acai-berry weight-loss supplements are to the Linda Litzke types of today.  Lined with a porous and highly-radioactive torbernite-charged grout, these jars dispensed drinking water saturated with radon gas and its radioactive progeny.  Health benefits were claimed, but the only proven reality of the radioactive water craze was a number of cases of terminal bone cancer.  Needless to say, the Revigator and similar offerings from other manufacturers aren’t safe to use as intended!  Radioactive quack crockery is highly collectible, so expect to drop a few benjamins on specimens in good condition.  My Revigator was a cheap local bargain, but it is missing the matching stand and lid.  It blows nearly 50 kcpm on a 2″ pancake Geiger counter placed within.

%d bloggers like this: