Challenge: Cameras on a Nuclear Reactor

[PixelRabbit]

First I had no clue where to put this but I have faith that our dear moderators will move it if there is a better place for it

As many of you know Mr. Rabbit works at the nuclear station. Over the years he has worked on the face of shut down reactors (still hot obviously but not "as" hot) and they use a lot of cameras to remotely do the work. Recently he has changed positions and is now in fuel handling on the live reactors and spends time in very less than desirable areas. One issue they are always trying to deal with is electronics and cameras in these areas, the radiation zaps them and you don't get a picture just interference.

I've been going around this in my head since I started getting interested in photography and I thought I might do well to toss it out there to all your brilliant minds and see if you guys may be interested in trying to think around the issue.

So the issue is radiation and electronics, various forms of shielding have been tried and distance from the camera out of the room seems to be the biggest issue?. I'm wondering if there are non electronic solutions somehow, go back in time and go oldschool somehow? The images have to be immediately relayed to the control room...

Looking forward to discussing this!

 

[runnah]

1. I am startled to learn that Canada has nuclear power.

2. My only suggestion would be a shielded cable system, but only have dealt with non-nuclear interference I don't know how that would work.

 

[Judobreaker]

Just throwing an idea out there: How about working with Faraday caging and mirrors?

I'm not sure how well this will work, I only have some minor experience with radiation used in radiotherapy (I work as a precision mechanic in the radiotherapy-field).
As far as I know radiation doesn't go around corners and passes through (most) mirrors so if you can make a cage which blocks radiation and use 2 simple mirrors you could protect the camera. Then all you need to do is protect the cables going out of the camera (probably using the same materials) so the signal can travel outwards.

If you could construct a good cage (probably with lead or something of the like) I think this could work...
Correct me if I'm wrong of course.

 

[Railphotog]

1. I am startled to learn that Canada has nuclear power.

I see you're in Maine. We have a nuclear power plant right next door to you in New Brunswick, Point Lepreau. Been plagued with problems since its recent overhaul though.

 

[amolitor]

What you want is a periscope. You can make them out of mirrors, prisms, or bundles of fiber optics. The last sort is called a fiberscope and, honestly, I'm sure these things are widely used in nuclear plants to inspect crap in the hot areas. There just isn't any other way.

 

[HughGuessWho]

Just throwing an idea out there: How about working with Faraday caging and mirrors?

I'm not sure how well this will work, I only have some minor experience with radiation used in radiotherapy (I work as a precision mechanic in the radiotherapy-field).
As far as I know radiation doesn't go around corners and passes through (most) mirrors so if you can make a cage which blocks radiation and use 2 simple mirrors you could protect the camera. Then all you need to do is protect the cables going out of the camera (probably using the same materials) so the signal can travel outwards.

If you could construct a good cage (probably with lead or something of the like) I think this could work...
Correct me if I'm wrong of course.

Problem solved.... NEXT

 

[PixelRabbit]

Just throwing an idea out there: How about working with Faraday caging and mirrors?

I'm not sure how well this will work, I only have some minor experience with radiation used in radiotherapy (I work as a precision mechanic in the radiotherapy-field).
As far as I know radiation doesn't go around corners and passes through (most) mirrors so if you can make a cage which blocks radiation and use 2 simple mirrors you could protect the camera. Then all you need to do is protect the cables going out of the camera (probably using the same materials) so the signal can travel outwards.

If you could construct a good cage (probably with lead or something of the like) I think this could work...
Correct me if I'm wrong of course.

This is an idea (mirrors) Mr Rabbit and I were throwing around but didn't realize it had a name, I asked him to draw up what was currently in use (if anything) in the different areas and from what he has described mirrors are not used right now.

, I'm sure these things are widely used in nuclear plants to inspect crap in the hot areas. There just isn't any other way.

Unfortunately you would be very surprised to learn what they use men for instead of cameras, hence thinking around this to get them less exposure.

 

[Judobreaker]

The Faraday cage is rather widely used with all kinds of electromagnetic radiation.
It's also a commonly known problem in buildings... The construction steel in buildings will sometimes act as a Faraday cage for wavelengths used for mobile phone networks and such which makes it hard or sometimes even impossible to get a decent reception in large (usually tall) buildings.

The mirrors is like the periscope amolitor mentioned (it works the same way, allowing you to look around a corner while radiation can't travel around that same corner).

 

[Gavjenks]

A faraday cage in the sense that the term is normally used (a literal cage) will not work for very high frequency radiation, because even a solid sheet of metal is still essentially a "mesh" large enough to allow most of the radiation through. To block such radiation, you need ideally high molecular weight materials in large amounts (effectively acting as millions of meshes in a stack), e.g. lead shielding.

The same design will work, but just replace "faraday cage" with "big honking thick (on the order of inches maybe, depending how far the camera is from the core) wall of lead"

Also, be aware that although a normal mirror will not reflect the vast majority of, say, gamma rays hitting it, it will still reflect SOME. And even a tiny portion of high energy radiation may fry your camera sensor. Adding in larger numbers of mirrors (each one exponentially reduces the rays getting through) or using a fiber optic cable will fix this issue if it is a problem, though.



Fiber optic in general just seems cheapest, and most useful. You could have fiber optic lines permanently installed pointing at all kinds of things in the reactor that you might want to look at, and then have them all lead to some shielded central area far away, where you can just plug the camera into any of them you want. Don't even need multiple cameras. Image quality would probably suck due to all the conversions and such, but should easily be as good as a standard gas station security camera for cheap. Which may be plenty good enough if all you're doing is seeing if some wall is cracked, or if something is on fire, or whatever.

 

[jake337]

Polaroid and scan? Or does radiation effect Polaroids?

 

[PixelRabbit]

A faraday cage in the sense that the term is normally used (a literal cage) will not work for very high frequency radiation, because even a solid sheet of metal is still essentially a "mesh" large enough to allow most of the radiation through. To block such radiation, you need ideally high molecular weight materials in large amounts (effectively acting as millions of meshes in a stack), e.g. lead shielding.

The same design will work, but just replace "faraday cage" with "big honking thick (on the order of inches maybe, depending how far the camera is from the core) wall of lead"

Also, be aware that although a normal mirror will not reflect the vast majority of, say, gamma rays hitting it, it will still reflect SOME. And even a tiny portion of high energy radiation may fry your camera sensor. Adding in larger numbers of mirrors (each one exponentially reduces the rays getting through) or using a fiber optic cable will fix this issue if it is a problem, though.



Fiber optic in general just seems cheapest, and most useful. You could have fiber optic lines permanently installed pointing at all kinds of things in the reactor that you might want to look at, and then have them all lead to some shielded central area far away, where you can just plug the camera into any of them you want. Don't even need multiple cameras. Image quality would probably suck due to all the conversions and such, but should easily be as good as a standard gas station security camera for cheap. Which may be plenty good enough if all you're doing is seeing if some wall is cracked, or if something is on fire, or whatever.

So the fiber optic is used to get from the lens/mirror assembly to the sensor and the distance is what degrades the image in combination with the lens/mirror assembly? Some of the things they have to see are very tiny and detailed, a small scratch in a fuel channel can be a big issue etc... so I would say that detail and image quality is an important part of the puzzle and likely why the cameras aren't as widely used to save dose.

 

[Heitz]

The problem here is that you're asking how to take a picture of 'light' without the light actually hitting the camera. The only way I see this can be done is by discriminating the visible spectrum from the spectra you don't want (X-ray, gamma, etc.). A faraday cage can do this if the mesh is of the correct size, but I assume that by then you'd also be losing most of the visible light too. Could a special prism do it? I don't know what prisms do to very short wavelengths .... But again idea is that you'd have to discriminate visible from unwanted.

Or you can stack 10,000 IR filters and hope for the best

 

[texkam]

Remember, you can't put too much water in a nuclear reactor!

 

[Judobreaker]

A faraday cage in the sense that the term is normally used (a literal cage) will not work for very high frequency radiation, because even a solid sheet of metal is still essentially a "mesh" large enough to allow most of the radiation through. To block such radiation, you need ideally high molecular weight materials in large amounts (effectively acting as millions of meshes in a stack), e.g. lead shielding.

The same design will work, but just replace "faraday cage" with "big honking thick (on the order of inches maybe, depending how far the camera is from the core) wall of lead"

Technically speaking a lead wall of 1m thickness is still a Faraday cage.

So the fiber optic is used to get from the lens/mirror assembly to the sensor and the distance is what degrades the image in combination with the lens/mirror assembly? Some of the things they have to see are very tiny and detailed, a small scratch in a fuel channel can be a big issue etc... so I would say that detail and image quality is an important part of the puzzle and likely why the cameras aren't as widely used to save dose.

Using fiber optics would replace the mirrors. Fiber cables can transport light in any way. Around corners, in a loop-de-loop, it doesn't really matter.
It's probably a good idea. ^^

 

[Gavjenks]

So the fiber optic is used to get from the lens/mirror assembly to the sensor and the distance is what degrades the image in combination with the lens/mirror assembly? Some of the things they have to see are very tiny and detailed, a small scratch in a fuel channel can be a big issue etc... so I would say that detail and image quality is an important part of the puzzle and likely why the cameras aren't as widely used to save dose.

It won't degrade very much in such a short distance. The video quality is more of an issue of the price of specialized software and hardware that can interface with fiber optics (not your typical camcorder... unless you put a dedicated laptop in there along with it or something), blah blah. Fiber optics are weird and probably rare for things like this, so quality will be comparatively expensive.

The lead box, on the other hand, could give you very high quality video for a few dollars of scrap materials and a cheap camcorder. But it has no obvious way to get the image out so that you can actually monitor it.



What about a camera PLUS a laptop inside the lead box? If the things you're looking for are things that can be detected by auto image analysis software, then you might not HAVE to actually get the signal out. The computer just detects when there's a crack and sounds an alarm by tripping a relay and sending a ton of electricity through a thick-ass copper cable that is either on or off and where interference doesn't matter. But I'm guessing that the things you need to monitor can't be trusted to be detected by image software.