From
Asahi Shimbun:
Japan faces the possibility of having to pay huge compensation to overseas victims of the Fukushima No. 1 nuclear power plant because it has yet to sign any international convention that defines procedures for filing lawsuits for damages from a nuclear accident that extend beyond a nation's borders.
While the Kan administration has compiled a framework to provide support to Tokyo Electric Power Co., the operator of the Fukushima plant, as it makes compensation payments, if lawsuits were filed overseas the total compensation could go much higher than current estimates of several trillions of yen.
There are three conventions which establish the standards for having the nation where a nuclear accident has occurred handle compensation lawsuits. One is the Convention on Supplementary Compensation for Nuclear Damage (CSC), which was agreed to by the International Atomic Energy Agency. Japan had been asked by the United States to join the CSC and has been considering the move. However, because of a longheld myth in Japan that accidents would never occur at a nuclear plant and other considerations, no decision was made to sign the convention.
--snip--
After the No. 5 Fukuryu Maru, a Japanese fishing boat, was showered with radioactive ash from a U.S. hydrogen bomb test at Bikini Atoll in 1954, the United States paid 720 million yen ($8.91 million) in compensation to Japan in a political settlement.
This article is much, much more than my selected excerpts and covers quite a bit of ground.
PB