Hiroshi Harada, a 75-year-old atomic bomb survivor and former head of the Hiroshima Peace Memorial Museum, poses for a photograph in front of a cenotaph for the victims of the 1945 atomic bomb, in the Peace Memorial Park in Hiroshima, western Japan, March 26, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 26, 2015. REUTERS/Issei Kato TPX IMAGES OF THE DAY

Makiko Kato, an 85-year-old atomic bomb survivor, poses in front of pictures of survivors' activities to convey the experience of being witness to the horrors of atomic bombs to young people, at Funairi Mutsumi-en, a nursing home for atomic bomb survivors, in Hiroshima, western Japan, March 27, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 27, 2015. REUTERS/Issei Kato 

Hiroshi Harada, a 75-year-old atomic bomb survivor and former head of the Hiroshima Peace Memorial Museum, stands near a red ball indicating where the atomic bomb exploded above Hiroshima city, at the meseum in Hiroshima, western Japan, March 26, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 26, 2015. REUTERS/Issei Kato 

Shigeo Ito, an 84-year-old an atomic bomb survivor, displays a 1944 family photo on a laptop computer that shows his late sister Yuki (rear, 3rd L), who was killed by the bomb, as he demostrates sharing the experience of being witness to the horrors of atomic bombs to young people, at an exhibition about the 1945 atomic bombings in Higashihiroshima, western Japan, March 27, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 27, 2015. REUTERS/Issei Kato TPX IMAGES OF THE DAY

Hiroshi Harada, a 75-year-old atomic bomb survivor and former head of the Hiroshima Peace Memorial Museum, poses for a photograph in front of a cenotaph for the victims of the 1945 atomic bomb, in the Peace Memorial Park in Hiroshima, western Japan, March 26, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 26, 2015. REUTERS/Issei Kato

Fumiaki Kajiya, a 76-year-old atomic bomb survivor and retired school teacher, speaks during an interview with Reuters at his home in Hiroshima, western Japan, March 27, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 27, 2015. REUTERS/Issei Kato

Hiroshi Harada, a 75-year-old atomic bomb survivor and former head of the Hiroshima Peace Memorial Museum, walks on Motoyasu Bridge near the Atomic Bomb Dome in Hiroshima, western Japan, March 26, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 26, 2015. REUTERS/Issei Kato

Fumiaki Kajiya, a 76-year-old atomic bomb survivor and retired school teacher, demonstrates how he uses hand-drawn "picture shows" to share the experience of being witness to the horrors of atomic bombs to children at his home in Hiroshima, western Japan, March 27, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 27, 2015. REUTERS/Issei Kato

Fumiaki Kajiya, a 76-year-old atomic bomb survivor and retired school teacher, poses for a photograph as he demonstrates how he uses hand-drawn "picture shows" to share the experience of being witness to the horrors of atomic bombs to children at his home in Hiroshima, western Japan, March 27, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 27, 2015. REUTERS/Issei Kato

Shigeo Ito, an 84-year-old an atomic bomb survivor, speaks during an interview with Reuters at an exhibition about the 1945 atomic bombings in Higashihiroshima, western Japan, March 27, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 27, 2015. REUTERS/Issei Kato 

Fumiaki Kajiya, a 76-year-old atomic bomb survivor and retired school teacher, looks towards the city center from the street in front of his home in Hiroshima, western Japan, March 27, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 27, 2015. REUTERS/Issei Kato

Makiko Kato, an 85-year-old atomic bomb survivor, holds a book recording survivors' experience of being witness to the horrors of atomic bombs for future generations at Funairi Mutsumi-en, a nursing home for atomic bomb survivors, in Hiroshima, western Japan, March 27, 2015. As the 70th anniversary of the world's first nuclear attack nears, many survivors still find it too painful to talk about. But with their ranks dwindling, others are determined to pass on their experiences to younger generations. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 27, 2015. REUTERS/Issei Kato 

Paper cranes, with one bearing a written message "Peace First!!!", are collected at an exhibition about the 1945 atomic bombings in Higashihiroshima, western Japan, March 26, 2015. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 26, 2015. REUTERS/Issei Kato

Scaffolding surrounds the Atomic Bomb Dome during maintenance work in Hiroshima, western Japan, March 26, 2015. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 26, 2015. REUTERS/Issei Kato

Visitors look at photographs and artifacts from the destruction caused by the 1945 atomic bombing, at Hiroshima Peace Memorial Museum in Hiroshima, western Japan, March 26, 2015. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 26, 2015. REUTERS/Issei Kato

A family looks at a photograph of the mushroom cloud of the atomic bomb blast at Hiroshima Peace Memorial Museum in Hiroshima, western Japan, March 27, 2015. A U.S. bomber dropped the atomic bomb on Hiroshima on August 6, 1945, killing about 140,000 by the end of the year, out of the 350,000 who lived in the city. The city still has some 60,000 survivors but their average age is approaching 80. Picture taken March 27, 2015. REUTERS/Issei Kato