Posted on August 17, 2021 in Uncategorized

Radiation’s Effects on Media

 

What Kind?

Radiation is not limited to radioactive materials. Electro-magnetic radiation from the sun touches nearly all life on Earth. Microwaves generate microwave radiation, and heating pads generate infrared radiation. Not all radiation is bad, but some can be dangerous. Nonionizing radiation includes the visible light spectrum and the bandwidths below it, while ionizing includes part of the UV bands and above. The difference between the two is that Ionizing EM radiation has enough energy to ionize something, meaning that when it strikes an atom or molecule, it has enough energy to remove an electron. Ionizing radiation has many applications, and not all of them are scary – the same UV radiation that can cause skin cancer can also sterilize equipment without chemicals.

 

Source: ScienceNotes.org

 

Ionizing radiation that comes from radioactive decay include alpha particles, beta particles, and gamma rays. The first two can be stopped with relatively little difficulty – alpha particles can be stopped by distance, or something as thin as a sheet of paper. Beta particles are lighter and higher-energy, so they take a thicker shield. A car door might protect you from beta particles. Gamma rays, which are the highest-energy kind of EM radiation, are where lead casings and thick concrete become necessary.

How long does media last if exposed to ionizing radiation?

 

Film

 

Photosensitive film exposed to radiation becomes speckly, and picks up a ‘fog’ after long-term exposure. Film cameras work by exposing photosensitive chemicals on a backing to light – if something is ‘overexposed’, the photographer let too much light in, or let the light in for too long, causing lightly-colored areas to look white and dark areas to appear much brighter than they did in person, and vice-versa for underexposure. Getting the right amount of radiation to the film is what gives you that perfect picture! But that’s all about non-ionizing – what about ionizing?

Ionizing radiation penetrates the plastics surrounding the film (camera, film canisters, etc.), and excites the film’s chemical coating in the same way light does, leading to strange white speckles across the film alongside a general ‘fog’ which worsened the image’s quality, according to NASA’s tests. The good news is that the effect stops getting worse after about 4 months of low-grade exposure (NASA exposed the film to the radiation you’d get up in space, unprotected by the atmosphere)!

Interestingly enough, this effect is how Kodak found out the US was testing nuclear devices in the 1950s. The government contaminated the strawboard (via fallout contaminating the rain and rivers used by their processing plants) that was used to ship film, so when that film got to where it was going, it was already partially exposed and therefore ruined.

 

VHS Tapes

 

VHS is a tape-based medium – but the information is stored magnetically, in binary. This greatly increased storage capacity, and some of the biggest computers still run on magnetic tapes. However, that doesn’t mean it’s better-equipped to survive radiation!

Radiation and magnets have a complicated relationship, but long-term (or short term high-volume) exposure to ionizing radiation can make bits flip, and the effect is only magnified the smaller the bits are. Even powerful magnets can slowly demagnetize when exposed to radiation in the long-term! VHS is notoriously delicate as a storage medium anyway, and shares many of the same issues that regular film does – the thin plastic used in both hates a lot of things! Heat, cold, too long in the sun (which is non-ionizing radiation!) too long without being played, being played too many times, you name it – VHSs can rot or degrade from it.

 

CDs/DVDs

 

CDs and DVDs work differently than magnetic media – a laser has etched the data onto the disc, and a laser is reading data off of the disc. Magnets are totally uninvolved, chemicals only minimally. Testing done by the USPS shows that sterilizing radiation doesn’t ruin the information on the disc! However, the plastic of the disc as well as its box started smelling burnt and turned a funny color during these tests. The information could still be accessed, though, making it a major upgrade to the VHS’s loss of quality upon exposure.

 

Electronics (and Modern Storage)

 

Radiation, specifically gamma radiation, makes complicated electronics stop working. Amazon’s “Chernobyl” series recreates the events of the famous power plant’s real-life meltdown and it’s resulting consequences. One scene shows a helicopter passing directly above the ‘spout’ of Cherenkov radiation created by the exposed reactor materials, and then crashing because it lost power. Further into the series, we see three young men go back into the plant only for their regular flashlights to fail.

Why? Well, they were basically hit with an EMP!

A beta particle is essentially a rogue electron or positron – where it hits, it ionizes, although their easy-to-stop nature means they aren’t too much of a threat unless you’re already too close. Gamma rays, on the other hand, are a much bigger problem, and go much further. A large burst of them like the kind released by a nuclear detonation, and the slow, steady kind released by an event like Chernobyl, are both really bad news for electronics.

Location and dose are critical factors in how the device fares. Would they start working again once removed from the source? Possibly! But because the gamma radiation is changing the physical attributes of the device where it strikes, it becomes less and less likely the longer it spends next to the radiation source.  Nuclear Engineering Magazine states that long-term exposure or big, one-time exposures can damage transistors into non-functionality even after they’re removed from the source. As mentioned before, they can also cause bit-flips, which will wipe stored data, too – if the radiation can get through the casing, it’s at risk. Any especially small memory systems using magnets may be vulnerable if unshielded! Including flash memory. Where Solid State Drives and Flash Drives are resistant to physical impact, they aren’t more resistant to radiation than their counterparts, because their method of storage – magnetization – is the same.

However, that doesn’t mean it’s impossible to protect electronics from radiation. You can harden devices against radiation just by picking a different casing, since both alpha and beta particles are fairly easily stopped given appropriate shielding. Gamma radiation is tougher to stop entirely but can be slowed. If the device was powered down at the time of exposure, it’s odds of surviving go up even further.

 

Sources:

https://www.neimagazine.com/features/featureprotecting-electronics-from-the-effects-of-radiation-5890599/

https://nepp.nasa.gov/docuploads/392333B0-7A48-4A04-A3A72B0B1DD73343/Rad_Effects_101_WebEx.pdf

https://www.popularmechanics.com/science/energy/a21382/how-kodak-accidentally-discovered-radioactive-fallout/

https://www.nytimes.com/2010/09/14/science/14atom.html

https://www.clir.org/pubs/reports/pub121/sec5/

https://hps.org/publicinformation/ate/q11162.html

https://www.slac.stanford.edu/econf/C010630/papers/T207.PDF