Mr. Science's Laboratory

science, art, photography, aviation history, constructed objects, mostly by Mr. Science and friends. Oh, and radioactive stuff. I studied physics and astronomy then had a career in aerospace engineering.

[mrscience2]

Audio amplifier chips on an integrated circuit wafer, manufactured circa 1981, viewed through an antique Bausch and Lomb folding magnifier; chips were made (I believe) by Delco for automotive use; from Mr. Science’s collection

[mrscience2]

Common Radioactive Household Items from the Atomic Age

(based on the display above that I made for our camp at Burning Man)

There are three radioactive elements that have been widely used in consumer goods: uranium, used probably since antiquity as a colorant in glazes and glass; thorium, used as an alloying element in metals and to improve optical glass; and radium, used since shortly after it’s discovery in 1898 in questionable/dangerous medical devices and luminous paint. Use of all three in consumer items has been drastically curtailed in our more enlightened times, roughly since the 1970′s. However, there are still a lot of these things around, and nearly every antique store has between several and lots of slightly radioactive things, mostly Depression glass made with uranium as a colorant. I walk around in antique stores with my Geiger counter on in my pocket just in case I walk by an incredibly hot ancient quack medical device, which are quite rare.

Uranium

First, Uranium: I love the color of the uranium glass mostly made in the 20′s - 40′s, though a few mostly non-U.S. firms may still make some of it. Most of it fluoresces vividly in UV light:

This glass is often called “depression glass” due to when it was made, or “vaseline glass” due to it’s somewhat vaseline-like appearance, but only the yellow-green color is radioactive. Most of this glass is not very radioactive as measured with a Geiger counter, between 2 and 10 times the normal background count which is about 20 counts per minute with my usual Geiger counter, and I drink out of these sometimes. I gave away 2 or 3 of these tumblers to the unusual few who seemed to prize them at Burning Man, one person clutching one to his chest like a Ring of Power as he left.

Then there’s Fiestaware; the vivid red-orange examples were made with Uranium in the glaze from the start up to at least the 60′s. Most of it I encounter now is newer and not radioactive. The radioactive stuff is surprisingly hot for kitchenware, at least 3000 counts/minute with my Geiger counter. Most of what I see is beta radiation which is absorbed before traveling past the upper skin layers and therefore not especially dangerous. However, Uranium acts as a toxic heavy metal in the body, so ingesting it is not recommended. This link expounds at great length on Fiestaware: https://www.orau.org/ptp/collection/consumer%20products/fiesta.htm

I wouldn’t recommend eating off the radioactive stuff anymore just in case (though i did as a child probably), but I consider it safe for casual handling. The web site above estimates that there may be up to several grams of uranium in a plate, perhaps a significant amount for chemical toxicity: https://www.ncbi.nlm.nih.gov/pubmed/18188051

This short video shows my Geiger counter, first measuring background, then a Fiestaware plate, which would eventually reach 3000 counts/min after the filter settles out:

Thorium

Next there is Thorium, used in various consumer items such as mantles for camping lanterns, glass in cameras, and high tech aerospace parts like turbine blades. Kodak, among others, made perhaps a million slightly radioactive cameras in the 50′s as well as military and commercial optics.

Comprehensive list of radioactive lenses: http://camerapedia.wikia.com/wiki/Radioactive_lenses

My current small collection of radioactive cameras: Kodak Motormatic, Pony 135 and Signet 30

These are not much above background radioactivity, though some of the larger military aerial camera lenses measure 3000 counts/minute at the rear of the lens.

Radium

The Curies isolated a gram of radium from a ton or several of uranium ore around 1900; it is about 2 million times more radioactive than uranium per gram, and they reportedly kept a gram or so in a bottle in the lab at one time partly to see the blue glow around it due to Cerenkov radiation in the air.

In the early pre-1930 or so days of radium work, it’s dangers were not properly known or respected, and a number of people died, most famously the radium dial painters, subject of more than one book. Here’s an example scary quack medical device, the Nuclear Jock Strap, from Carl Willis’ blog: https://carlwillis.wordpress.com/2017/02/03/a-nuclear-jockstrap/

Despite this history radium was still used for luminous paint into at least the 60′s, being replaced by less hazardous substances such as tritium in later years. Many older clocks with once luminous dials have radium, though they no longer luminesce because the alpha radiation has damaged the zinc sulphide locally. The quantities in dial paint are probably a few nanograms. It is well to not disturb the paint to avoid breathing or ingesting dust from it. Some of the old quack medical devices were really hot and shouldn’t be opened or disturbed without a glove box radioactive handling facility.

My small collection of clocks with radium paint:

Here are the NRC regs for possessing artifacts with radium; the short version is, up to 100 items with radium paint are ok in one location without a specific license. https://www.nrc.gov/reading-rm/doc-collections/cfr/part031/part031-0012.html   Watchmakers are also exempt from specific licensing, usually.

So, Mr. Science, are any of these things actually dangerous?

Probably not (other than the cautions noted above). None of the items above will give you nearly as much whole body radiation as flying on the airlines at 40000 ft. It’s difficult to tell if small exposures over long periods, like frequent airline flights, cause any increase at all in cancer risk; according to models based on rapid large exposures, the risk would be much too small to see in cancer statistics, and it could actually be zero. Radiation exposure on a plane: https://spaceweatherarchive.com/2015/07/31/rads-on-a-plane-hot-seats-in-first-class/

[mrscience2]

The Loneliness of the B-52 Tail Gunner

Early model B-52′s were the last American bombers to have gunners stationed in the tail; later models moved the gunner to the front with the rest of the crew, with a televised view to the rear for the gunner, and radar. The gunner usually entered the aircraft through a rear lower hatch. It was possible to go between the front crew area and the tail during flight along a narrow catwalk over the bomb bay, but the aircraft had to be depressurized and I think this was rarely done. The manual says that for flights longer than 16 hours, the copilot could go back and relieve the tail gunner. Another interesting note is that during war emergency takeoffs, the gunner should close the flash curtains over the canopy on takeoff to avoid flash blindness from nearby nuclear detonations.

Some features in the image (taken recently in a museum aircraft): center top, the optical gunsight which could be directed to view anywhere in the aft hemisphere; below that the radar scope, radar controls, and handles for moving the aiming point manually. Note the ashtray far left; not much else to do on long flights.

Unlike the rest of the crew, the tail gunner didn’t have an ejection seat (and was the only enlisted crew member, the rest were officers); the canopy could be jettisoned or the entire turret in front of the gunner could be jettisoned to bail out manually. On the other hand, the tail gunner was the only survivor in at least one crash, the entire rest of the airplane having absorbed most of the damage.

I suspect that the ride in turbulence was rough; sitting on the ground the tail gunner station was moving around some in the wind due to the enormous vertical tail just above it.

I would like to hear from any retired tail gunners, as I am working on an exhibit involving the tail gun position.

[mrscience2]

The B-52 Circular Slide Rule

In the days before the handheld or laptop computers we all take for granted, we had to figure out takeoff and landing distance and other vital information for our airplanes from boring charts; except for many military pilots, who had these brightly colored circular slide rules for takeoff and landing distance and many other useful things:

This one, from 1963, for a B-52G (now out of service), has tiny masking tape marks left by a crew (upper right on left image) to use for braking distance from a V1 engine failure, not originally marked on the slide rule. Only a few hundred of these were probably made, and I had never seen one or known of them, despite having worked on B-52 sustaining engineering, until i found this one in an antique store. It’s leather case is marked “Confidential” due to having performance information for a nuclear-capable intercontinental bomber, but I think it’s ok to look at it now.

When I used to fly and maintain a B-52 engineering sim in the late 70′s, we didn’t take off or land with it, so I didn’t need to know these things. (We were mostly interested in low level terrain following).

You may message me if you suddenly develop a pressing need to know takeoff or landing distances for the B-52G; please include temperature, takeoff weight, and whether or not you are carrying GAM-77′s.

Takeoff side:

landing side:

[mrscience2]

Art Car in the Storm  -- 2012

i shot this at Burning Man 2012 during a howling dust storm, after which i had to stagger back to camp with my eyes closed, having forgotten my goggles when i rushed out to photograph in the storm.