Shigeko Sasamori, who was severely burned at 13 when a nuclear bomb exploded over Japan and later, in the United States, championed peace and found comfort in helping others as a nurse’s aide, died on Dec. 15 at her home in Marina del Rey, Calif. She was 92.

Her son, Norman Cousins Sasamori, confirmed the death.

Ms. Sasamori spoke gently, but resolutely, against nuclear war to audiences that included students, United Nations interns and guides, and members of the U.S. Senate. Her message carried no rancor toward the United States.

“I have a mission to tell people that this should not happen again,” she told a Senate subcommittee investigating the effects of nuclear war on human health in 1980. “I tell people how horrible it was and how horribly we suffered even though we were children. The next generation of children has come into the world, and I fear for them.”

Her death came two months after the Nobel Peace Prize was awarded to Nihon Hidankyo, a grass-roots Japanese organization of atomic bomb survivors, for its efforts to rid the world of nuclear weapons.

On the morning of Aug. 6, 1945, Ms. Sasamori was one of the students assigned to clear the streets of Hiroshima of debris to make the city easier to evacuate if necessary. She heard a buzzing sound from the sky and told a classmate, “Look at the white thing falling from that airplane.”