The team transmitted information using fast neutrons produced in the decay of radioactive material. The system could be useful in situations where electromagnetic radiation is blocked.
A report said the carrier believed the shipment had been delayed at their facility but later said it could not be located.
Last month, Chinese authorities sought to downplay the problem, saying minor fuel rod damage was to blame for radioactive gases that had built up at the site.
According to reports, four FedEx employees came into direct contact with the package and were sent away for medical examination.
The Dutch National Institute for Public Health and the Environment said the radioactive substances were man-made.
As space runs out at the plant, experts have urged the Japanese government to begin releasing filtered water from Fukushima into the sea or air.
A North Carolina man who attempted to use radioactive material to poison another man has been handed a 78 month prison sentence, according to officials.
The site was operational between 1954 and 1994 but is now in the process of being decommissioned.
Radioactive pee is just one of the strange incidents cited in a new report from the Australian Radiation Protection and Nuclear Safety Agency.
The radiation is not a threat to human health, but it's a previously unknown risk of coastal nuclear power plants.
Greenpeace tests show overall contamination from key isotopes has fallen somewhat, but lingers, especially in places such as forests.
Criminal gangs are exploiting poor relations between Russia and the West.