Tritium.... Disturbing measurements

A few weeks ago my Physics teacher was showing us his geiger counter. It was ticking because he had been injected with a radioactive dye, and he wanted to show that he was indeed radioactive.

I told him I had a tritium vial on my flashlight, and offered it to be measured. He took it and his geiger counter reacted quite obviously; it began to tick faster; I was warned to keep my flashlight out of my pants pocket

I am currently in Munich with my grandparents and they have 3 geiger counters (rock collecting and Chernobyl). Now, today we did some measurements. Without my flashlight, the geiger counter measured .04 u(pico)SV / hour, presumably from cosmic radiation. With the light/tritium vial, we received a measurement of 0.14 u(pico)SV / hour!! Although this measurement is weak, it is in itself fairly disturbing.

Any other comments/ measurements?

-tom

Probably the measurement would be less for a glowring.

Um, β radiation is so weak that it cannot penetrate human skin and does not even leave the vial; it collides with phosphors to fluoresce them. Geiger counters detect single decays producing α or β particles but surprisingly cannot reliably detect the really lethal gamma (γ) rays.

Are you sure it was a Geiger Counter? As I remembered a Geiger Counter cannot detect Tritium ([font=Arial, Helvetica, sans-serif]3H) [/font]Beta Radiation (note the 3--and all numbers below--in 3H is intended to be a super-script but the software is stripping it for me):

Monitoring Instruments:

[font=Arial, Helvetica, sans-serif]The beta pancake detector is used with the Geiger counter for finding and measuring beta radiation, and will detect all beta radioisotopes used at Michigan State University except 3H and 63Ni. It does not detect those nuclides because their betas are too low in energy to penetrate the window of the detector. Radioisotopes which may be detected reliably with the beta pancake are 14C, 35S, 33P, 32P, 45Ca, 36Cl, and other beta emitting nuclides.[/font]

[font=Arial, Helvetica, sans-serif]The low energy gamma (LEG) probe is used with the Geiger counter to detect and measure gamma radioisotopes of various energies. It is most efficient for 125I, but will perform adequately for 51Cr, 111In, 60Co and other gamma emitting nuclides. These detectors will also detect low energy x-rays, such as those emitted by beta emitters producing Bremsstrahlung radiation.[/font]

[font=Arial, Helvetica, sans-serif]Another instrument in common use is the liquid scintillation counter. It is necessary to use it in radiation safety surveys for 3H and 63Ni, since no other instrument will detect these nuclides. Liquid scintillation counters work for both beta and gamma nuclides for quantifying what is in a sample. It is not an adequate primary method of evaluating contamination surveys, however, since samples measured consist of wipes of the areas of suspected contamination. If the contamination is not removable, the wipe will not pick it up, and contamination will not be detected. It is also possible for only part of the contamination present to come up on a wipe, not giving an accurate measurement of the contamination present.[/font]

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Radium is another possibility on older clocks and watches--but does not sound like it is a possibility here.

It is always best to understand the limits that are typically allowed for radiation. One source lists 1 mSv / year for the average person and 100 mSv / 5 years for workers around radiation (m=10^-3). I am not sure what your units are, but u(pico)/hr would seem to indicate (u*pico = 10^-6*10^-12 = 10^-18 / hr--I could be very wrong here--just a guess) or roughly 10^-19 Sv per year. Or your reading of about 1/10 * 1/1,000,000,000,000 of the max-recommend dose for the average person. pretty small amount of radiation.

There are a lot of materials that are radioactive:

Natural Sources of Radiation

PBS some sources of high background radiation:

Brazil Nuts:

This is the world's most radioactive food due to high radium concentrations 1000-times that of average foods.​

The US Capitol Building in Washington DC:

This building is so radioactive, due to the high uranium content in its granite walls, it could never be licensed as a nuclear power reactor site.​

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It may be some other source of radiation in your flashlight besides the Tritium vial that you are measuring.

-Bill

Keep your cellphone outta yer pants too, that is a guaranteed way to get radio frequency energy

Sometimes I think Geiger counters should be tuned daily...

My science teacher a couple years ago drew on a new discovery: the counter clicked faster when placed near a banana than the isotope sample on his deak...supposely uranium crystals..

The same counter didnt work when someone brought in a smoke alarm with "traces of americum 241"


bananas are radioactive.....um...

>alpha and beta
Geiger counters can be used for these. It depends on the wand/detector you have. There are detectors that have only a very thin (and fragile) window, I think it' s mica but I'm not sure. Those windows allow detection of alpha and beta. Often they have a closable metal cover, sometimes they're flat so-called "pancake" detectors meant to be put right up against a source.

Possibly there's some tritium contamination from the manufacturing process on the outside of the glow-ring. It's hydrogen, after all, it's slippery stuff, will go through almost anything eventually.

>banana
There's potassium in bananas, and there could be fertilizer used on them as well.

Remember -- any wad of fresh dryer lint will show you a definite level of radioactivity above the background level in the area. That's because alpha and beta are ionized, and will stick to whatever stops them, particularly fuzzy clothes. Pull off all the loose fibers and wad them up in a dryer vent trap and you'll measure concentrated sources (that decay quite rapidly).

Pull a lot of air through a very fine filter paper and the same thing will happen. This is still a good way to monitor for changes in background, if you do it regularly and know the normal level measured with your setup.

When I was a kid my dad was doing this air-filter check every day, as routine background measurement for a biology lab that had to know the background -- and there were some winter days he'd come home and make sure we went out and told all the neighborhood kids, don't eat the snow this week.

I'd guess those and other weeks through the year he was also making sure we didn't buy fresh local milk til the radioactive iodine levels dropped, but I don't remember. Just a kid ....

That was in the mid-1950s when the Nevada nuclear tests were sending fallout across the US. He couldn't tell us _why_ we shouldn't eat the snow in any detail at the time, it was a secret for years afterwards.

Illum_the_nation said:

bananas are radioactive.....um...

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Bananas ARE radioactive

Morelite said:

Bananas ARE radioactive

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Go to my Natural Sources of Radiation link (as above) and search for Bananas (listed radioactive food)...

You should be very happy to know that beer is about 1/10 as radioactive as Bananas.:buddies:

Many foods are more radioactive based on the levels of natural radiation in the soils where they are grown... Every living thing is slightly radioactive because of Carbon 14 (created by cosmic rays and used for "carbon" dating organic objects).

-Bill

Here's a tritium-related thread which links to the other tritium-related threads.

I got rid of my tritium because of what tom's teacher measured... I am somewhat "paranoid" that I will pass through someplace with a geiger counter, get detected, and be fined for owning tritium.... hey, it could happen?

-David

Get rid of your dad's wrist watch with the "dead" glow paint that is over 20 or 40 years old... If it is over 40 years old, it is still almost as radioactive as the day it was made.

A Tritium glow watch is not going to be a problem (in the US, those uses are legal) or even detected (because it is behind aluminum/Steel/plastic/glass.

If you are undergoing implanted radiation therapy, you can trigger radiation detectors and have a long interview.

Detected:

A man who recently had received radiation treatment for a medical condition set off a nuclear alert detector on a fire engine, prompting police to close down a roadway in Escondido while authorities searched for a nuclear weapon.The Fire crew's radiation monitor sounded Tuesday when the man and his friend walked past the crew on their way to fill a gas can. The Nuke Alert monitor sounded again as the men walked back to their vehicle. Firefighters notified the San DiegoCounty Sheriff's Department after they drove by the men's vehicle and the monitor sounded a third time. Sheriff's deputies pulled over the driver and detained him and his passenger for about one hour while they confirmed that the man was not carrying a nuclear weapon and that he had received radiation treatment. The radiation monitor was purchased with Homeland Defense Department grant money."

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-Bill

Pull a lot of air through a very fine filter paper and the same thing will happen.

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this is more true than you think! There is quite a bit of radiation all around you all the time. Back in high school a friend of mine and i did some experimenting with a geiger counter and we discovered nothing more radioactive than a vacuum cleaner with a just used bag!

Geiger tubes generally can detect betas and gammas. You need a very thin (generally mica) window tube to detect alphas.

From the manual for a CDV-700 (model 6, Victoreen, 1961):

The probe comprises a nickel-plated brass shield with a window which may be opened in order to admit beta radiation. Within the probe is mounted a plug-in type geiger tube which is sensitive to moderate and high energy beta radiation and to gamma radiation down to low energies.

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Field calibration on this instrument is done with a beta source. I think the scale is itself calibrated for beta activity, and is only really reliable as a qualitative measurement device for gammas. Nevertheless, measuring a decaying medical gamma source (Thallium 201 from a radioisotope scan performed for medical reasons) the half-life was confirmed, and the overall biological elimination was measureable.

Jim

Tested out an americium sample on a thin-window geiger tube a few days ago.

Definitely proves that alphas are blocked effectively by air! From a foot away, clicks were only slightly higher than background.

With the americium source (harvested from a fire alarm) a couple of millimeters (distance of plastic mesh shield on tube) away, it increased to 150,000 c/m!

A 1.0mm aluminum shield effectively blocked the alphas, and let us see the secondary gammas (low energy) that Am241 emits. Maybe some gammas from the decay products, but I think mainly from the Am241. Even at about 3mm, we were only getting slightly higher than background readings.

Jim

I'm not sure about your units. Did you read u (as in mu, micro, 10^-6) or pico (10^-12)? Let's assume you read micro Sv (worst case scenario). 0.14 micro Sv/hr * 1 yr = 0.14 micro Sv/hr * 8760 hr/yr = 1.2 milli Sv/year. Typical background radiation: 2.4 milli Sv/year (see wikipedia/sievert).

I would call this harmless, especially since you typically do not absorb the full dose.

Also, I find it curious that the reading was in Sievert. Sievert is a unit used to indicate the damage done by radiation of a certain type absorbed by a certain type of tissue. The counter does not know this; it should read Gray (essentially the same unit as Sievert, without care for type of radiation or tissue). For absorption in the skin (that's all Tritium can do) you'll get to Sievert from Gray by multiplying the Gray value with 0.01, or dividing by ten. So the counter should read 0.14 micro Gray/hr; if this is from Tritium and you absorb everything in your skin, you'll get 0.014 micro Sv/hr, or 0.12 milli Sv/year. Totally harmless. (see Wikipedia/Sievert, the 0.01 factor for Gray to Sievert comes from Q=1 [electrons from Tritium] and N=0.01 [skin]).

(All assuming that the calibration of the counters were correct. Those things are finicky.)

maybe it only increased as a result of him having radioactive dye?

You said you gave him the light with vial and the counter went up. Could it have been him?

leukos said:

Probably the measurement would be less for a glowring.

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I totally agree with you. Plus his machine likely needed fine tuning.

BB said:

Are you sure it was a Geiger Counter? As I remembered a Geiger Counter cannot detect Tritium (3H) Beta Radiation (note the 3--and all numbers below--in 3H is intended to be a super-script but the software is stripping it for me):

Monitoring Instruments:



Radium is another possibility on older clocks and watches--but does not sound like it is a possibility here.

It is always best to understand the limits that are typically allowed for radiation. One source lists 1 mSv / year for the average person and 100 mSv / 5 years for workers around radiation (m=10^-3). I am not sure what your units are, but u(pico)/hr would seem to indicate (u*pico = 10^-6*10^-12 = 10^-18 / hr--I could be very wrong here--just a guess) or roughly 10^-19 Sv per year. Or your reading of about 1/10 * 1/1,000,000,000,000 of the max-recommend dose for the average person. pretty small amount of radiation.

There are a lot of materials that are radioactive:

Natural Sources of Radiation

PBS some sources of high background radiation:


[/indent]It may be some other source of radiation in your flashlight besides the Tritium vial that you are measuring.

-Bill

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What about Radon since it is a natural source?

Smitty762,

Most-all of the members posting in this thread have been gone for quite some time. It's probably just a coincident. :laughing:

I kid. The thread was last responded to 10.5 years ago.

:welcome:

~ Chance