A programming urban legend features a coder who worked at a Soviet train station. The computer at the station inexplicably crashes on a predictable timescale; upon investigation, the coder discovers that the crashes occur when cows are shipped through the station. Further investigation reveals that intense radiation from the cows causes the computer to crash.
Is this story true or plausible? Did the USSR introduce radioactive food into the food supply?
The answer to your last question is "yes" but I find the story itself utterly impossible. Radiation can cause computer chips to malfunction, but to penetrate just the chip housing (not to mention computer casing, the building, train car, or more than some meters of air) the radiation from the supposed radioactive cows would need to be in form of gamma radiation. Alpha and beta particles simply cannot penetrate even the flimsiest of obstacles and attenuate rapidly in air as well.
Gamma ray sources sufficiently powerful to be even detectable in a neighboring building as a train passes by would be very rapidly lethal to any animal unfortunate enough to have ingested one.
However, it is true that the USSR introduced radioactive food inadvertently into food supply following the Chernobyl accident. The largest source of radioactivity in food was milk from cows outside the initial exclusion zone (30 km from the plant). While the exclusion zone was evacuated, farmers outside the zone were told to continue their work, and pastures and meadows were used as if nothing had happened. Unfortunately, the grass their cows ate was in many cases strongly contaminated by radioactive iodine-131 in particular.
Before Soviet authorities could get their act together and begin monitoring food supplies, significant quantities of contaminated milk (and quantities of other foodstuff) had been shipped and consumed. Milk was largely responsible for the largest single documented health damage from Chernobyl accident: radioactive iodine in it concentrated in the thyroid glands of children and adolescents, resulting to (estimated) 4000 cases of thyroid cancer, including 15 deaths as of 2006.
The sad thing here is that iodine-131 contamination is very short-lived and merely banning milk and vegetable sales from the more contaminated regions for a few months would have prevented thyroid cancers almost entirely.
Sources
Medvedev, Z. (1990). The Legacy of Chernobyl.
The Chernobyl Forum (2006). Chernobyl’s Legacy: Health, Environmental and Socio-Economic Impacts.
EDIT: Spelling and formatting.