Nuke gauge source

[MRM]

Back when I was trained on the gauge, I seem to recall the safety instructor mention to our group that if the cesium source tip were placed in your shirt pocket (left side, by your heart), you would likely die within about an hour.

I've been wondering if I recall that correctly, or if I just dreamed that up sometime between then and now.

Understandably, there is not much on-line about it, probably because of security reasons, etc.

Is that anything close to what you have heard before about that? Does the source emit that much radiation in an hour?

 

[MRM]

Update:
Based on some fairly crude estimates, and using some websites with accuracy that cannot be thoroughly verified, I think the number of hours necessary to do lethal, acute, damage to the heart tissue when the source is in the front shirt pocket is between 8 and 16 hours.

...from this, I think what I heard about 14 years ago is not "1 hour," but it would take "1 day."

Does that sound familiar to anyone else?

 

[GeoPaveTraffic]

Not ringing any bells with me, but then again it is closer to 25 years since I had gauge training.

Mike Lambert

 

[emmgjld]

I recall something about 1 day exposure for ultimate fatality. I have always tried to carry the gauge in a lower pocket.
Must have worked ... Been testing for 46 years - ain't dead yet!
When I took the course 35 years ago. very little use of the scare tactics. I had been using the gauge since 1967, when only the RSO needed instruction. I have noticed the increasing use of scare statistics, since about 1985. More so from the State Health Dept. types, usually with advanced degrees. FAH!

 

[Ron]

There are two radioactive isotopes in a Nuke gauge.... Cesium 137 is used for density and Americium 241 is used for moisture. Both are extremely low strength...somewhere in the range of 10 millicuries to 50 millicuries (compare that to the strength of a source we would use for doing radiographs of structural steel welds, which would be from 60 to 100 curies)....having said that, any unshielded radiation source can be dangerous. I doubt that anyone would die from having a nuke gauge source in their pocket, though localized radiation damage would likely result. That localized damage could be detrimental, depending on which pocket you decided to keep the source in!

Radiation is a light wave...as with any light wave, distance is a significant factor. For any ionizing radiation source time is also critical. If you are exposed to a light radiation source for a long period of time, it has the same effect as being exposed to a strong source for a short period of time. Similarly, close proximity to a weak source has the same as more distance from a stronger source...keeping in mind that distance decay is a squared function while time decay is not.

 

[BigH]

I'll post a picture of a nuclear guage operator in India when I find it . . . soon. Cheers

 

[GeoPaveTraffic]

Ron makes a good point. Another factor is the type of radiation. As I recall, Cesium is a gama source and Americium is an alpha source. Alpha radiation can't penetrate much, but I expect a source adjacent to the skin could cause real damage.

Mike Lambert

 

[MRM]

Thanks, all.

I think we all agree that the gauges are obviously pretty safe when you shield, keep your distance, and limit your time of exposure.

I don't really recall that comment from the safety trainer being intended as a scare tactic of any kind. It seemed more like just a matter of fact thing they mentioned. If anything, it seemed like he was making a case for why we had to be there taking the course...so a few years later, out of nowhere, I get a random thought in my head (that doesn't really matter anymore to me directly):

If nuke gauges are so "low level" why, then, all the costly regulations surrounding them? Are they justified? Was that safety trainer even correct at all?

Sort of like a "fact check" more than a decade later... (I certainly never claimed I was that quick....)

I noticed that one would require about 500,000 to 1,000,000 mrem of exposure in a short period of time to cause radiation poisoning, extreme damage, or death (if that exposure is directed to a vital part of the body somewhere). It seems that even with the 8miC or so cesium source, at point blank range over the heart, it could deliver that amount of mrem over the course of 24 hours. (feel free to check my math and concepts, if you wish, as I used an online calculator to convert the source strength to mrem in terms of exposure time-I may be way off somewhere in my understanding).

I think that for all of us, if we took the proper precautions, then we received something on the order of what they say in the manual (an additional 100 mrem or so over the course of a year; much less than anything that would cause damage, and on par with what we receive in a year from natural sources already).

So in the end, I'm at least a little more satisfied that the costly regulations are justified to some degree, and that safety trainer probably was speaking the truth!

 

[BigH]

In Malaysia they are required to put out "cones" at least 3 m in diameter from the nuke. I have found that many actually push out the rod a bit so they can get it into the hole easier - I learned to outline the base plate form and then use it - worked fine. I know of only one guy who had any radiation on his badge (when they were required) - he put his badge on the top of the nuke at night when he went to bed . . .

 

[MRM]

It seems to me that even if you pushed out the source tip to stick it in the hole, you still won't be subjecting yourself to too much extra radiation since: a) the source is a distance away from you (i.e., not at point blank range to any vital parts, and b) your exposure time is still limited. Still not the recommended practice to unshield the source, but I've seen others do it. I've always done what you said, BigH: just position the gauge over the hole correctly and the rod goes down there pretty easily and consistently...