An Irish woman from Derry who lives 60 miles from the Tokaimura nuclear reactor said no warnings were issued alerting people in her area to the uranium leak.
Ms Fiona Kelly, said she heard about the explosion at 2 p.m. from a bilingual Japanese television service. The explosion occurred at 10.30 a.m. local time.
Ms Kelly lives in Omiya in Saitama prefecture, the next prefecture to where the Tokaimura leak occurred. Japan is divided into prefectures, which are similar to Irish counties.
Ms Kelly said information about the explosion was broadcast on Japanese television and radio for much of the day. She watched a live press conference held by the company which owns the nuclear reactor.
Some schools in Ibaraki Prefecture, where the leak occurred, were closed and people were asked to stay in doors, Ms Kelly said. Although the Japanese media covered the leak extensively, Ms Kelly said was not alarmed. "I'm not really frightened," she said. "I've been listening to it on the radio and watching on the television and it doesn't seem to be that close to us." Ms Kelly's partner, who is Japanese, had heard about the explosion earlier and was not alarmed either.
Matt Miller, an American living in Saitama Prefecture, also said no warnings had been issued to people in the area. He said he had heard little throughout the day. People in Koshigaya, the town where he lives, did not seem alarmed, he said.
"Nobody said anything and they didn't seem worried," Mr Miller said.
He learnt from the Internet of an evacuation of the area around Tokaimura, but did not know whether there was any danger to neighbouring Saitama prefecture.
He said he had also found out from the Internet that the wind was blowing north and that radioactive emissions were unlikely to reach Saitama prefecture.
About 1,000 Irish people live in the Tokyo region.