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How to find a tiny radioactive source while doing 70 kph

ansto.gov.au

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Re: How to find a tiny radioactive source while doing 70 kph

#31

Post by SanjayMehta »

a2800276 wrote: post #28
dmurray wrote: post #3

Good job, but a lot of the reports really exaggerate the size of the search area. > in the formidable conditions of the outback... > It’s fair to say finding a piece of equipment the size of a button in a vast desert was no easy task Let's not go too far here. It was two metres from the road and they knew exactly which 1400km of roads to check.

Also: “... we’re a sophisticated nuclear nation and in many ways, we’re world leaders that punch above our weight when it comes to nuclear expertise and stewardship." The stewardship claim bit seems maybe a bit overstated considering they weren't able to secure an object the size of a button leading to it "falling off the back of a truck" My minds eye is seeing a crocodile Dundee type holding a beer in one hand and c…

Your minds eye didn't see the koala riding shotgun?

Re: How to find a tiny radioactive source while doing 70 kph

#32

Post by HPsquared »

hilbert42 wrote: post #13
gggggg5 wrote: post #4

Earlier quoted context omitted.

I was rather baffled by so many sources claiming that this would be super difficult to find. It seemed like such a simple task to drive up and down roads with some radiation detection equipment, log the data and investigate any hotspots. Well, I guess it was? Or maybe I'm severely underestimating the complexity of this?

The news was a bit of a beat-up and the chances of just accidentally stumbling on it out there were pretty remote to essentially nil. But what's authority to do? If some kid had found it and took it to school there'd be hell to play. Based of its stated radiation signature it was always going to be easy to find. Right, it was a simple but nuisance task and took about as long as expected.

It was probably a mistake to report it to the public while it was still missing. That probably attracted a bunch of amateurs who could have ended up finding it. Far safer to look for it quietly first.

Re: How to find a tiny radioactive source while doing 70 kph

#33

Post by defrost »

wnkrshm wrote: post #23
defrost wrote: post #12

Earlier quoted context omitted.

It's not too amazing. Perth has a few companies that do this work for a living - as a grind job, flying contracts for an actuall million line kilometres of 256 channel radiometric mapping at anything from $7 to $15 AU per line kilometre for mineral exploration. This has been ongoing for 50 years (see: Radiometric Map of Australia) and I'm slighlty baffled why a plane wasn't flown along the road on day one. Realistic…

I want to know this other story, I haven't found it by cursory search - what should I be searching for?

Pokhran-II was a series of five nuclear bomb test explosions conducted by India in May 1998, Pakistan responded with six underground nuclear tests at the Chagai and Kharan test site conducted fifteen days after India's last test.

It was all abit unexpected at the time and the US was interested to know how it came to be that Australians were present.

Re: How to find a tiny radioactive source while doing 70 kph

#34

Post by jacquesm »

The paranoid part of me has me thinking that all this sounds tailor made to showcase a product and a capability in a relatively safe setting. And you're really so hot on nuclear tech: don't lose your sources. That way you don't have to show off later on how good you are at finding them, aka the 'hero model' applied to nuclear physics.

Re: How to find a tiny radioactive source while doing 70 kph

#35

Post by jacquesm »

defrost wrote: post #19
noja wrote: post #17

Earlier quoted context omitted.

Depends if the wind blows it away.

It's steel around a ceramic slug mix doped with Cs-137 .. think about cutting 8mm off the end of a 6mm diameter steel bolt and dropping that to the ground. It's going to take a good wind to blow that very far.

Especially once it drops a little bit below grade. Or gets covered with a bit of sand on the windward side. Unless picked up it was never going to be more than a few meters away from where it was lost.

I'd love to see some re-enactments and the spread of the spots where the pallet ended up after being lost on step one, that might give some indication as to whether it was found near its original landing point or further away from it.

Re: How to find a tiny radioactive source while doing 70 kph

#36

Post by defrost »

xrayarx wrote: post #26
defrost wrote: post #12

Earlier quoted context omitted.

It's not too amazing. Perth has a few companies that do this work for a living - as a grind job, flying contracts for an actuall million line kilometres of 256 channel radiometric mapping at anything from $7 to $15 AU per line kilometre for mineral exploration. This has been ongoing for 50 years (see: Radiometric Map of Australia) and I'm slighlty baffled why a plane wasn't flown along the road on day one. Realistic…

What I don't understand is, what kind of technology is it? It is obviously great. The technical explanation is not there

The simplest spectrometer is dark sealed tubes of doped sodium iodide crytals with a counter at the ends.

When an energetic gama burst hits a bit of crystal it flashes in a manner that gives up the energy .. over the course of a second and a few thousand events (normal background radiation) you have a spectrum [1].

You no have an indication of all the radiation all arounf the tube.

All around. With no indication of direction. Literally they could have come from anywhere, up, down, left, right, behind you, etc.

What we have here appears to be a vertical tube (or tubes) with mobile masking templates that rotate about and provide some axis of ingress information coupled with any energetic flahes that appear at the same instant.

There is some topographical statistics that needs to be performed and overall there are reduced signal levels (as some incoming gammas are masked and never make a flash) but you can end up with a positional image of where various radiation sources are in the space about the tube.

The other wrinkle they gloss over ('compressed', 'needs fewer counts') suggests (it's either obfuscated or I haven't read deeply enough) they have an eigen library of responses (ie. mean Australian background, Pure Potassium, Pure Uranium, Pure Thorium, Cs-137) baked in to facilitate faster recognition of spectrum patterns.

It's a pattern matching in N^256 type problem in a space that reduces to about N^11 or so when an SVD is applied .. and there are ways to "cheat" and do this faster on the fly.

[1] https://en.wikipedia.org/wiki/Gamma_spectroscopy

Re: How to find a tiny radioactive source while doing 70 kph

#37

Post by laci37 »

HPsquared wrote: post #32
hilbert42 wrote: post #13

Earlier quoted context omitted.

The news was a bit of a beat-up and the chances of just accidentally stumbling on it out there were pretty remote to essentially nil. But what's authority to do? If some kid had found it and took it to school there'd be hell to play. Based of its stated radiation signature it was always going to be easy to find. Right, it was a simple but nuisance task and took about as long as expected.

It was probably a mistake to report it to the public while it was still missing. That probably attracted a bunch of amateurs who could have ended up finding it. Far safer to look for it quietly first.

I guess that was because they were afraid of it getting stuck in a tire. If I found a strange metal cylinder in my tires, I would probably pick it up a try to find out what it is.

Re: How to find a tiny radioactive source while doing 70 kph

#38

Post by HPsquared »

laci37 wrote: post #37
HPsquared wrote: post #32

Earlier quoted context omitted.

It was probably a mistake to report it to the public while it was still missing. That probably attracted a bunch of amateurs who could have ended up finding it. Far safer to look for it quietly first.

I guess that was because they were afraid of it getting stuck in a tire. If I found a strange metal cylinder in my tires, I would probably pick it up a try to find out what it is.

Did they close the road and/or put a checkpoint in place? That'd eliminate that risk.

Re: How to find a tiny radioactive source while doing 70 kph

#39

Post by willcipriano »

a2800276 wrote: post #28
dmurray wrote: post #3

Good job, but a lot of the reports really exaggerate the size of the search area. > in the formidable conditions of the outback... > It’s fair to say finding a piece of equipment the size of a button in a vast desert was no easy task Let's not go too far here. It was two metres from the road and they knew exactly which 1400km of roads to check.

Also: “... we’re a sophisticated nuclear nation and in many ways, we’re world leaders that punch above our weight when it comes to nuclear expertise and stewardship." The stewardship claim bit seems maybe a bit overstated considering they weren't able to secure an object the size of a button leading to it "falling off the back of a truck" My minds eye is seeing a crocodile Dundee type holding a beer in one hand and c…

"Call that a radiation source? Now that's a radiation source. " he said between bouts of violent vomiting.

Re: How to find a tiny radioactive source while doing 70 kph

#40

Post by dsfyu404ed »

curiousgal wrote: post #7
gggggg5 wrote: post #4

Earlier quoted context omitted.

I was rather baffled by so many sources claiming that this would be super difficult to find. It seemed like such a simple task to drive up and down roads with some radiation detection equipment, log the data and investigate any hotspots. Well, I guess it was? Or maybe I'm severely underestimating the complexity of this?

Well imagine if the pellet fell on the road, another car drove by and the pellet got stuck in one of the car's tire grooves. The car eventually makes it to a parking lot, or to the back of someone's ranch. Good luck finding it, short of monitoring hospitals for radiation poisoning patients.

You might as well make up a story about a kangaroo eating it and then someone hunting and eating the 'roo.

The odds for any one small object to get not only picked up but picked up and not tossed back out are astronomically tiny.

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