How much radiation can an LED flashlight stand?

I watched the mini-series "Chernobyl" over the last day or two. In one scene, three reactor workers are sent under the melting reactor core to open some drainage valves. (If the water tanks weren't drained, there would have been a huge steam explosion scattering much more radioactive contamination).

As the three men are proceeding to the valves, their flashlight (large reflector diving lights, I would guess) start to fail. My first reaction was "And they don't even have a couple of AAA EDC keychain lights with them!". But then I thought "There's probably so much radiation there, solid-state lights invented 30 years later would probably have failed, too." I don't know if their lamps were failing because of radiation or just for more ordinary failure reasons.

So I wonder, just how many REM ( or grays or sieverts...there's a lot of different units out there) can an LED stand before it degrades down to uselessness? On the other hand, it's probably much more than any unprotected human could withstand anyway.

More of a theoretical question, I suppose.

Bill

(excellent, chilling, series, by the way...with no easy answers for anyone! And the three men survived their mission, though one died of a heart attack 19 years later. )

Their lights probably failed because Russian made stuff sucked back then.

I don't know, but I know that Fukushima is still dumping enormous amounts of radioactive water into the ocean since the disaster started and is the biggest nuclear cover up in history. In reality it makes every other nuclear disaster look like a joke, the robots going in to measure the radiation and to look at the damage that were made of metal were melting from radiation exposure.

bionerd23 on you tube has more info about radiation than I will ever understand. Very neat high risk urban exploration.

Found a few interesting articles.
https://hps.org/publicinformation/ate/q11162.html
https://www.sciencedirect.com/science/article/abs/pii/S0378775316303573

"Gamma radiation is penetrating and can affect most electrical equipment. Simple equipment (like motors, switches, incandescent lights, wiring, and solenoids) is very radiation resistant and may never show any radiation effects, even after a very large radiation exposure. Diodes and computer chips (electronics) are much more sensitive to gamma radiation. To give you a comparison of effects, it takes a radiation dose of about 5 Sv to cause death to most people. Diodes and computer chips will show very little functional detriment up to about 50 to 100 Sv. Also, some electronics can be "hardened" (made to be not affected as much by larger gamma radiation doses) by providing shielding or by selecting radiation-resistant materials."

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Their old school direct drive incan lights should have weathered those sub-insta-lethal conditions fine, so there may be a grain of truth to Byk's hypothesis; if dynamo lights work but battery lights don't, then it'd have to be something to do with the battery not holding up to gamma ray exposure, maybe thin membranes within shorting/failing.

In theory, a modern LED light should perform much worse as there are transistors involved in the driver; things get very sketchy once you start throwing random pulses of energy into a switch junction.

I sort of wonder how radiation affects batteries in lights myself.

That show was full of technical bullshit, pretty much every episode twisted my knobs, nice acting and filmwork aside.

That said, I recall some old-style incan flashlights being part of a test for radiation effects on electronics. They handled over 100Gy with no ill effects. That's a whole-body dose that causes Neurovascular effects in under a minute, and certain death.

An LED light can have components that are more sensitive, such as diodes, but even these can take 50-100Gy+ with nary an ill effect.

Probably the biggest concern would be neutron activation leading to the flashlight itself becoming radioactive so even away from the initial exposure the use would be getting irradiated. That, however, would require an extremely high neutron activity, something not in effect in the scenarios of the series, and itself deadly to the carrier in minutes.

A dude on Reddit says it's because the air is ionized, which would mean the battery already has charges going on at both ends even without a circuit, so when you try to connect a circuit it won't do anything. Sounds logical..

It's possible to cause random bit flipping in electronics simply by being in higher altitudes like Denver due to the increased background radiation. In general, as silicon dies get smaller and thinner, they're more prone to this effect.

You know in the back of my mind I think I keep a supply of incandescent stuff on hand because I'm thinking if shtf a old fashioned incandescent bulb might just be more reliable then a led with circuits in it. Not sure if my thinking is correct or not. Anybody care to comment?

thermal guy said:

You know in the back of my mind I think I keep a supply of incandescent stuff on hand because I'm thinking if shtf a old fashioned incandescent bulb might just be more reliable then a led with circuits in it. Not sure if my thinking is correct or not. Anybody care to comment?

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This is correct. A tungsten filament will survive higher radiation levels than any semiconductor (except for the rad-hard stuff). I don't know how it would affect the batteries though, so a hand-cranked flashlight might be a good emergency option.

More evidence that high radiation levels can wreak havoc on electronics - Tepco experienced multiple failures in their robotic cameras while trying to remotely inspect the Fukushima reactor.

thermal guy said:

You know in the back of my mind I think I keep a supply of incandescent stuff on hand because I'm thinking if shtf a old fashioned incandescent bulb might just be more reliable then a led with circuits in it. Not sure if my thinking is correct or not. Anybody care to comment?

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We're talking downtown Hiroshima levels of radiation, which unless you're living on an airbase/next to a silo isn't a remotely realistic scenario. EMP is the far likelier event, which anything stored shielded survives equally.

StarHalo said:

We're talking downtown Hiroshima levels of radiation, which unless you're living on an airbase/next to a silo isn't a remotely realistic scenario. EMP is the far likelier event, which anything stored shielded survives equally.

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I pretty much agree that radiation that makes a light dead would end up being terminal to people around it. I seriously doubt we will be attacked by non nuclear EMP devices when those who are going to send a rocket at us from far away are going to also have a nuke on it.

Lynx_Arc said:

I seriously doubt we will be attacked by non nuclear EMP devices when those who are going to send a rocket at us from far away are going to also have a nuke on it.

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The two likeliest EMP scenarios are a full nuclear attack starting with an EMP-specific extra-atmospheric burst, which could be sufficient to black out a few states with zero blast/heat/radiation on the ground (followed by strikes on the aforementioned air bases and silos, so no radiation for most people.) The other is solar flare.

You see I'm not worried that someone is going to nuke us. It kinda just makes sense.The US has natural resources.buildings factories etc. someone nukes us they can't use it. But, a large scale EMP well that just shuts us down and if they were to win" which of corse they wouldn't " they would have access to all that. Sorry for getting off track. But would a incandescent not survive better then a led in a EMP attack?

thermal guy said:

You see I'm not worried that someone is going to nuke us. It kinda just makes sense.The US has natural resources.buildings factories etc. someone nukes us they can't use it. But, a large scale EMP well that just shuts us down and if they were to win" which of corse they wouldn't " they would have access to all that.

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The old school superpower war idea is that both sides lose - you begin with an EMP attack so the other side has no communication/coordination, then strike their strike capability so they can't defend. But if both sides can anticipate that, then you just end up with both sides blind and defenseless. The current thinking has a lone nuclear blast in a proxy country or a dirty bomb in a metro area, neither of which means anything for our flashlights..

thermal guy said:

Sorry for getting off track. But would a incandescent not survive better then a led in a EMP attack?

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That's questionable if the Carrington Event had flaming telegraph wires; most anything wired, or filament-ed, would not survive that. But anything stored shielded would survive the same.

And getting back on track, if you want to know how your flashlight handles higher levels of radiation that you might encounter on a daily basis, store it in some bananas or brazil nuts.

StarHalo said:

And getting back on track, if you want to know how your flashlight handles higher levels of radiation that you might encounter on a daily basis, store it in some bananas or brazil nuts.

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:thinking::thinking:

Yep bananas and some nuts give off radioactive. Read something like that years ago. Something to do with Potassium.

Mr. LED said:

:thinking::thinking:

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Those are the most radioactive substances the average person encounters daily; a banana is ~1,500 times more radioactive than a smoke detector.

StarHalo said:

Those are the most radioactive substances the average person encounters daily; a banana is ~1,500 times more radioactive than a smoke detector.

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Bananas are high in potassium and all potassium contains a tiny bit of 40​K, which is radioactive. Bananas are a pretty weak source though, way less than the dial on an old radium watch face or a Fiestaware dinner plate from the 1950s - 1960s, where they used uranium oxide to get that reddish-orange color that didn't fade over time. I am not making this up.