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Australians scour desert for dangerous radioactive capsule smaller than a penny

nytimes.com

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Re: Australians scour desert for dangerous radioactive capsule smaller than a penny

#171

Post by AlbertCory »

rukuu001 wrote: post #168
anakaine wrote: post #89

Earlier quoted context omitted.

No moose, bears, wolves, cougars, or other alpha predators in Australia though. About the worst are wild dogs / dingos, though they typically won't be a problem unless they're in a pack. I'll take Australian dangers over North American every day of the week.

Hello, Australian here. Yes, for 85% of the country, risk is small. Crocodiles are the only major danger, and they're isolated to the far north of the country. But they are truly terrifying, in that they are silent and invisible in the water, intelligent, and capable of watching a human for days to learn their routine and plan an ambush.

I was in Cairns & a little north of there for a bit. Certainly never went all the way to Cape York.

Although I did go on a kayaking expedition to Dunk Island, where there were only four 2-person kayaks, unusually high waves, and my boat-mate asked, "Are we going to sink?" Obviously we didn't.

Of course this is all for laughs, but some HN'ers are incapable of that.

Re: Australians scour desert for dangerous radioactive capsule smaller than a penny

#172

Post by userbinator »

jl6 wrote: post #170
Animats wrote: post #135

Here's what gauge sources like this look like.[1] Here are some packed for shipping. bolted to a crate, as described in the NY Times article.[2] The locks are $8 Master Lock combination padlocks, probably just to keep people from opening the things by accident. The lock looks optional on the model in [2]. The lock is on the shutter end, anyway. The cover plate that gives access to the source for replacement is secure…

Wow, I thought maybe these devices were available only through some kind of secure government channel, but nope, “Add to cart” right there. I guess at least they have this footnote: “Note: Users must be licensed to possess them before they can be purchased.”

You can always request to purchase one, but I doubt they'll just ship it without checking who you are first.

Re: Australians scour desert for dangerous radioactive capsule smaller than a penny

#173

Post by CyberDildonics »

martyvis wrote: post #137
epaulson wrote: post #104

The article didn't really explain the original purpose of the now-missing capsule, other than it was part of a sensor used in a mine. Can anyone explain a bit more what the original purpose of the sensor it was part of was? What did the mine need a bit of radiation to measure?

We used radiation sources and detectors at the steelworks for thickness gauge - you set them on either side of the plate and measure the lost and from that calculate the steel thickness very accurately. I presume in a mine it could be used say on a conveyor belt where you measure the lost radiation to help determine the density or weight of the ore.

That's just an xray with a single pixel

Re: Australians scour desert for dangerous radioactive capsule smaller than a penny

#174

Post by pxmpxm »

BetterGeiger wrote: post #167

Radiation detection is my specialty. This source is Cs-137, few hundred mCi. It's easy to detect within a few seconds at distances of a few tens of meters or more with professional detection equipment if there is direct line of sight. If it was knocked off the road, though, the question will be if it fell into a crack or other such place because then the radiation is somewhat shielded and it would take much more meas…

[flagged]

Re: Australians scour desert for dangerous radioactive capsule smaller than a penny

#176

Post by krisoft »

throwanem wrote: post #132
krisoft wrote: post #108

Earlier quoted context omitted.

> The surveyors would be safe enough barring a forced landing or breakdown very near the source Weird assumption. Forced landings anywhere are unsafe. They are also very rare, because aircraft are quite reliable. The chances of the surveyors having a forced landing near the capsule must be minuscule (tiny danger zone compared to the extent of full search area, small probability of an aircraft having a forced landing…

Great catch, and you're right: lots of things can go wrong in a desert whether there's radiation involved or not, so we'd have needed those helicopters either way. This is why we work in teams - don't be shy about anything else you see me missing.

> don't be shy about anything else you see me missing

I would think we need to clarify the theoretical and practical limits of the detectors.

Depending on how the sensors work the search might look very different.

If you can get some expensive lab gear and distinguish the radiation of this source from the background from hundreds of kilometers then you only need to measure at a few strategic locations to triangulate it.

If you need to get a sensor within ten meters from the source before it can be detected then you need to lug the sensor around on the ground. That would be too low for a manned aircraft to fly at.

How fast does the sensor detect? If the sensor can detect up to 100 meters but need 5 second to measure that will make the search much different than if it can measure with 500hz for the same distance.

Do we think we can sense only the source or also the places the source has been at? Does it leave a detectable trace?

What of these is hard limit by physics (nobody, for no amount of money can build a better detector) vs limit of resources (it would be very expensive to do x)? If it is a limit of resources how does detector quality scales with resources spent?

Without having solid answers to these it would be foolish to jump at designing a search method.

Re: Australians scour desert for dangerous radioactive capsule smaller than a penny

#177

Post by derbOac »

riffic wrote: post #151
karmakaze wrote: post #4

Here's a story about a lost capsule[0] that ended up being made into building material for the wall of an apartment if you think something small isn't worth being concerned about. [0] https://en.wikipedia.org/wiki/Kramatorsk_radiological_accide...

this seems to happen quite frequently according to a linked article about orphan sources. https://en.wikipedia.org/wiki/List_of_orphan_source_incident...

Stuff like that is frightening to me because they're known incidents. I wonder if there's a way to estimate the number of unknown ones.

Re: Australians scour desert for dangerous radioactive capsule smaller than a penny

#178

Post by sn9 »

BetterGeiger wrote: post #167

Radiation detection is my specialty. This source is Cs-137, few hundred mCi. It's easy to detect within a few seconds at distances of a few tens of meters or more with professional detection equipment if there is direct line of sight. If it was knocked off the road, though, the question will be if it fell into a crack or other such place because then the radiation is somewhat shielded and it would take much more meas…

This is an interesting algorithm problem.

Given the parameters to maximize detection and minimize time/resources, how would you direct a drone or something to find the capsule?

How would that change with 2 drones? 4? 8? As many drones as there are flyable Geiger counters in the country?

Re: Australians scour desert for dangerous radioactive capsule smaller than a penny

#179

Post by toss1 »

karaterobot wrote: post #114

> They believe that vibrations from the truck caused the sensor to shake apart and also dislodged a mounting bolt, leaving a hole in the bottom of the box. The capsule is believed to have fallen out of the sensor, through the bolt-hole, onto the surface of the truck, and bounced off into the road. I have a bag of locking washers I would be more than happy to donate if it makes this kind of thing less likely to happen…

These Nord-Lock washers [0] are excellent for that purpose. Do NOT use common split-washers, throw them away — they can actually speed the unlocking & loss of a nut.

(No relation, just a satisfied customer after finding they work well after being strongly recommended by a racecar engineer I know)

[0] https://www.nord-lock.com/nord-lock/

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