Answer to Question #11162 Submitted to "Ask the Experts"

Category: Radiation Effects — Effects on Materials

The following question was answered by an expert in the appropriate field:

Q

My question is in regard to the effect of radioactivity on nonliving matter and, specifically, electrical systems. What happens to things like record players, radios, intercom systems, TVs, and the like when exposed to beta and gamma rays? I have read conflicting information, including a claim that the effects would worsen and lessen as the radiation source drew nearer and farther away. Does the radiation exposure break down the physical material or does it mess with the signals received by the devices? Or both? Would the effects go away if the devices were removed from the presence of the radiation source?

A

Radiation effects on electrical equipment depend on the equipment and on the type of ionizing radiation to which it is exposed.
 
First, beta radiation has little, if any, effect on electrical equipment because this type of ionizing radiation is easily shielded. The equipment housing and the construction of the parts within the housing will protect the equipment from beta-radiation (high-energy electrons) exposure.
 
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.
 
Some electronics do exhibit a recovery after being exposed to gamma radiation, after the radiation is stopped. But the recovery is hardly ever back to 100% functionality. Also, if the electronics are exposed to gamma radiation while unpowered, the gamma radiation effects are less.
 
Ionizing radiation breaks down the materials within the electrical equipment. For example, when wiring is exposed to gamma rays, no change is noticed until the wiring is flexed or bent. The wire's insulation becomes brittle and will break and may cause shorts in the equipment. The effect on diodes and computer chips is a bit more complex. The gamma rays disrupt the crystalline nature of the inside of the electronic component. Its function is degraded and then fails as more gamma radiation exposure is received by the electronic component.
 
Gamma rays do not affect the signals within the device or the signals received by the device. Nonionizing radiation (like radio signals, microwaves, and electromagnetic pulses) DO mess with the signals within and received by the device. I put a cheap electronic game in my microwave oven at home. It arced and sparked and was totally ruined. I didn’t waste any more of my time playing that game.

Hope this helps.

John P. Hageman, MS, CHP

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